EPA-560/1-76-009
CHEMICAL TECHNOLOGY AND
ECONOMICS IN
ENVIRONMENTAL PERSPECTIVES
TASK III-CHLOROFLUOROCARBON EMISSION CONTROL
IN SELECTED END-USE APPLICATIONS
ENVIRONMENTAL PROTECTION AGENCY
T-9XIC SUBSTANCES
)N, D.C. 20460
1
IBER 1976
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EPA-560/1-76-009
CHEMICAL TECHNOLOGY AND ECONOMICS IN
ENVIRONMENTAL PERSPECTIVES
Task III - Chlorofluorocarbon Emission Control
in Selected End-Use Applications
Contract No. 68-01-3201
Project Officer
Irving J. Gruntfest
Office of Toxic Substances
Environmental Protection Agency
Washington, D.C. 20460
Prepared for
Environmental Protection Agency
Office of Toxic Substances
Washington, D.C. 20460
November 1976
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NOTICE
This report has been reviewed by the Office of Toxic Substances,
Environmental Protection Agency, and approved for publication*
Approval does not signify that the contents necessarily reflect
the views and policies of the Environmental Protection Agency*
Mention of tradenames or commercial products is for purposes of
clarity only and does not constitute endorsement or recommenda-
tion for use*
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PREFACE
This report presents the results of Task III, "Chlorofluorocarbon
Emission Control in Selected End-Use Applications," of a project entitled
"Chemical Technology and Economics in Environmental Perspectives." The
project is being performed by Midwest Research Institute under Contract
No. 68-01-3201 for the Office of Toxic Substances of the U.S. Environmental
Protection Agency. Dr. Irving J. Gruntfest is the project officer. This
program has HRI Project No. 4101-L.
Dr. Thomas W. Lapp is the project leader for this contract. Par-
ticular credits for authorship or partial authorship of portions of this
report include the following: Dr. Lapp, Chapters I, III, and V;
Mr. Thomas Weast, Chapter III; Dr. Ralph Wilkinson, Chapter III; and
Mr. Howard Gadberry, Chapter IV. All authors contributed to Chapter II.
Mr. Burl Kinder provided technical assistance for the area of refrigera-
tion and air conditioning. This program is under the supervision of
Dr. Edward W. Lawless, Head, Technology Assessment Section, Environmental
and Materials Sciences Division.
MRI expresses its sincere appreciation to the many companies and
organizations that provided technical information for this report.
Approved for:
MIDWEST RESEARCH INSTITUTE
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CONTENTS
Page
List of Figures. .......... .... vii
List of Tables ...................*...*. JLx
Section
I Introduction. .................... 1-1
References. .................... 1-3
II Summary and Conclusions II-1
r
Refrigeration and Air Conditioning. .......... 11-2
Foam Blowing Agents II-5
Cleaning-and Drying Solvents* ............ II-7
, +
III Refrigeration and Air Conditioning. III-l
•
Home Refrigerators and Freezers .......... Ill-2
Mobile Air Conditioning Ill-12
Chiller Systems 111-32
Commercial Food and Beverage Refrigeration. .... Ill-51
References Ill-65
IV Foam Blowing Agents ................. IV-1
Chlorofluorocarbon Consumption in Plastic Foams . . IV-1
Flexible Urethane Foams IV-2
Rigid Urethane Foam Production IV-21
Summary of Chlorofluorocarbon Consumption and
finis s ions IV-3 7
Polystyrene and Polyolefin Foams. ......... IV-40
Control Systems for Chlorofluorocarbon Emissions. . IV-41
References ............. IV-59
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CONTENTS (concluded)
Section Page
V Cleaning and Drying Solvents. ............. V-l
Cold Cleaning V-3
Vapor Cleaning and Degreasing . ...... V-10
Dry Cleaning Industry .......... V-36
References. ..................... V-41
Appendix - List of Reviewers. . ........••....••• A-l
vi
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FIGURES
Figure Title Page
III-l Typical Hermetically Sealed Home Refrigeration Unit. . . Ill-5
III-2 Refrigerant Reclamation System . . Ill-13
III-3 Typical Mobile Air Conditioning System Ill-17
III-4 R-12 (with oil) Loss Rate Versus Temperature Ill-21
III-5 Composite Diagram of Chiller Systems . . . IH-33
III-6 Centrifugal Chiller System 111-37
III-7 Reciprocating Chiller System . 111-38
III-8 Schematic of Current State-of-the-Art Commercial Food
and Beverage Refrigeration Systems .......... Ill-56
III-9 Typical Old Commercial Food and Beverage Refrigera-
tion System ........* 111-58
IV-1 General Flan for Flexible Slab Foam Plant. ....... IV-5
IV-2a Schematic of Traversing Foam Head Machine. . IV-7
IV-2b Stationary Head, Foam Trough Machine IV-7
IV-3 Schematic Layout of a Flexible Urethane Foam Molding
Line ("hot-mo Id ing" depicted) IV-17
IV-4 Sandwich Panel Production - Continuous Process ..... IV-29
IV-5 FC-11 Adsorption on BPL Activated Carbon ........ IV-44
IV-6 FC-12 Adsorption on BPL Activated Carbon IV-45
vii
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FIGURES (concluded)
Figure Title
V-l Solvent Loss as a Function of Freeboard Height/
Tank Width Ratio V-9
V-2 Typical F-113 Vapor Degreaser •••• V-ll
V-3 Vapor Degreaser Solvent Loss as a Function of
Temperature •••••••••••••••••••.. V-14
V-4 Typical Carbon Adsorber System • V-18
V-5 Offset Sump Vapor Degreaser V-35
viii
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TABLES
Table Title Page
III-l Home Refrigeration Usage and Replacement in 1976. ... Ill-4
III-2 Air Conditioning and Refrigeration Service Repairmen
in the U.S. in 1976 by Category Ill-8
III-3 Permeation Constants, Oil Present Ill-20
III-4 R-12 Calculated Loss Rate from Auto Air Conditioning
System, NBR Hose with R-12 and Oil . 111-22
III-5 Estimated Quantity of R-12 in Grocery Stores (1975) . . Ill-53
III-6 Total Estimated Replacement Cost of Refrigeration
System in Supermarkets and Small Grocery Stores ... Ill-62
IV-1 1975 Flexible Urethane Foams, Estimated Production by
Foaming Process ................... IV-3
IV-2 Typical One-Shot Flexible Foam Formulations ...... IV-9
IV-3 Model Plant - Flexible Polyether Slab Foam IV-10
IV-4 Fluorocarbon 11 Concentration in Breathing Zone Air
of Foam Manufacturing Facilities. .......... IV-12
IV-5 Model Flexible Urethane Foam Molding Plant. IV-18
IV-6 Distribution of Chlorofluorocarbon Losses, Molded Foam. IV-20
IV-7 U.S. Rigid Foam Consumption - 1975. IV-21
IV-8 Model Urethane Foam Boardstock Plant. IV-27
IV-9 Model Foam Core Structural Panel Plant IV-31
ix
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TABLES (concluded)
Table Title Page
IV-10 Model Foam-in-Place, Cavity Filling Plant IV-34
IV-11 Chlorofluorocarbon Consumption and Emissions,
Urethane Foams IV-38
IV-12 Estimation of Chlorofluorocarbon Emissions from
Urethane Foams - 1975 IV-39
IV-13 Maximum Amounts and Concentrations of Chlorofluoro-
carbon ............... IV-49
IV-14 Potential Control of Chlorofluorocarbon Emissions
from Foams IV-52
IV-15 Calculated Savings/Cost Ratio for Chlorofluorocarbon
Recovery ....................... IV-55
IV-16, Calculated Savings/Cost Ratio for Molded Foam Parts. . . IV-57
V-l Commercial Carbon Absorption Units V-20
V-2 Calculated Savings/Cost Ratio for F-113 Using Carbon
Adsorption . V-22
V-3 Calculated Savings/Cost Ratio from Increased Freeboard
Height V-25
V-4 Calculated Savings/Cost Ratio from Refrigerated
Condensing Coils V-27
V-5 Calculated Savings/Cost Ratio for Refrigerated Freeboard
Chillers V-31
V-6 Savings to Cost Ratio for the Use of Covers V-34
V-7 F-113 Solvent Consumption Rates. . V-38
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SECTION I
INTRODUCTION
The technical controversy over whether certain chlorofluorocarbons
are destroying the earth's protective ozone shield has evolved into a
public issue. Legislation is being considered at both the state and federal
levels to limit or ban the use of certain of these materials. While many
technical questions remain to be answered, responsible public officials
and regulatory agencies are trying to determine the technical and economic
feasibility of using alternative chemicals, of substituting mechanical
devices, and of reducing emissions from selected end-use applications. In
addition, they seek to identify the social consequences resulting from
the regulation of the various uses of these materials.
It should also be noted that not all chlorofluorocarbons or fluoro-
carbons are considered to be equally detrimental to the ozone layer nor
are these compounds the only halogenated species in the upper atmosphere.
The five halocarbons covered in this report are those of commercial sig-
nificance that may be damaging to the ozone layer. Other commercially
available chlorofluorocarbons are, at this time, considered to be less
hazardous to the ozone layer.
Midwest Research Institute (HRI) recently published a report on the
evaluation of feasible chemical alternatives to selected chlorofluorocar-
bon uses*l' Other studies on chlorofluorocarbons have dealt with strato-
spheric effects, biological effects of ozone reduction, human health ef-
fects, and a review of the "fluorocarbon industry."—' A study conducted
by Syracuse University Research Corporation offered an appraisal of en-
vironmental hazards of one and two carbon fluorocarbons,2/ Another major
study was a preliminary impact-assessment of possible regulatory actions
to control atmospheric emission of selected halocarbons.ft/ Numerous govern-
mental reports have been published on the economic and energy impacts of
complete chlorofluorocarbon regulation.
The objective of this study was to document the sources of emis-
sion of F-ll, F-12, F-13, F-113, and F-114 within the use areas of re-
frigeration and air conditioning, the foam-blowing industry, and clean-
ing and drying solvents. For each source of emission, feasible emission
1-1
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control procedures or equipment were to be identified, with an evalu-
ation of the effectiveness or efficiency of control and the cost for
each suggested control method.
This study was not directly concerned with the current ozone deple-
tion hypothesis or the environmental ramifications of that hypothesis.
No judgement on that question should be inferred from any of the results
of this study.
The three areas of application stated above account for approxi-
mately 40% of the total consumption in 1975 of these five chlorofluoro-
carbons. In terms of specific areas, the refrigeration and air condi-
tioning industry consumes the largest percentage (28%), followed by the
foam-blowing applications (7%). Cleaning and drying applications consume
the lowest percentage (5%) of these three areas.^/ HEX has worked closely
with industry in this evaluation of the sources of chlorofluorocarbon
emission and the possible methods for controlling these emissions. It is
conceivable that some of these methods could be employed and emissions
reduced to a level such that a ban on the use of selected chlorof luoro-
carbons may not be necessary in certain use areas. Industry, however,
must be willing to acknowledge the deficiencies and poor practices that
exist and strive to correct their problems.
Throughout the literature and in discussions with personnel directly
involved with, the industry, several different designation systems are
widely used for the halocarbons. In all industries, other than, refrigera-
tion, the halocarbons are given an F prefix (fluorocarbon) while in the
refrigeration industry the compounds have an R prefix (refrigerant). Thus,
F-12 and R-12 are the same compound, only the prefix is different and re-
flects the custom of different industries.
This document is intended to be useful to policy makers and the pub-
lic in understanding the feasibility,effectiveness and cost of control-
ling emissions of the five chlorofluorocarbons during their use in the
three areas of application. It is organized in a manner which we feel will
provide the greatest utility to the reader. The next section summarizes
the findings of this study with respect to the control of emissions from
each of the three use areas. Sections III through V present a detailed
discussion of the technical considerations to be applied to emission con-
trol in the areas of refrigeration and air conditioning, foam-blowing
applications, and degreasing and dry cleaning solvents. For each of these
areas, the sources of emission are identified and feasible methods of
emission control are shown but no attempt has been made to select the
single most attractive method or to provide any rank-order of the meth-
ods.
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REFERENCES
1. Midwest Research Institute, "Technical Alternatives to Selected
Chlorofluorocarbon Uses," EPA Contract No. 68-01-3201, Task I,
Publication No. EPA-560/1-76-002, February 1976.
2. "Fluorocarbons and the Environment," Report of Federal Task Force
on Inadvertent Modification of the Stratosphere (IMOS), Council
of Environmental Quality, GPO No. 038-000-00226-1, June 1975.
3. Howard, P. H., P. R. Durkin, and A. Hanchett, "Environmental Hazard
Assessment of One and Two Carbon Fluorocarbons," EPA Contract
No. 68-01-2202, Technical Report No. TR-74-572, EPA Report No.
560/2-75-003, NTIS No. PB-247-419 (1974);
4. Arthur D. Little, Inc., "Preliminary Economic Impact Assessment
of Possible Regulatory Action to Control Atmospheric Emissions
of Selected Halocarbons," EPA Contract No. 68-02-1349, Task 8,
Publication No. EPA-450/3-75-073, NTIS No. PB-247-115, September
1975.
5. Chemical Marketing Reporter, p. 9, September 1, 1975.
1-3
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SECTION II
SUMMARY AND CONCLUSIONS
Evidence that chlorofluorocarbons may be detrimental to the earth's
ozone layer was first reported about 2.5 years ago* Since that time, nu-
merous experimental and theoretical studies have been made on the effect
of specific chlorofluorocarbons on ozone* Studies have also been conducted
to identify substitute chemical and alternative methods for delivering
goods and services now provided by chlorofluorocarbons and to determine
the economic and commercial ramifications which would occur _if the uses
of these chemicals are regulated*
Earlier studies of the possible economic and commercial impacts are
exemplified by the topical areas of a preliminary economic impact assess-
ment of possible regulatory actions* governmental assessments of the eco-
nomic and employment impacts of possible regulatory actions, and a study
of alternatives to selected current.chlorofluorocarbon use applications*
These studies have been referenced in this and earlier reports.
The purpose of this study was to identify the potential sources of
chlorofluorocarbon emission for three of the major end-use applications
of F-ll, -12, -13. -113, and -114, and to identify current and potential
methods by which the emissions from these sources can be controlled. For
identified methods of emission control, the efficiency of the method and
the economics of its application were to be determined. In applicable
areas, the feasibility, cost, and effectiveness of new or modified oper-
ating and/or maintenance procedures were to be studied. The three areas
chosen for study were (1) refrigeration and air conditioning; (2) foam
blowing applications; and (3) cleaning and drying applications* These
areas appear to present the greatest potential for possible emission con-
trol. The lack of technically and economically feasible substitutes for
these use categories suggests that control of emission is one alternative
that merits serious consideration. This study considers the technical
and economic feasibility of emission control strategies for each of these
uses*
The results of this study can be summarized as follows for each use
category.
II-1
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REFRIGERATION AND AIR CONDITIONING
Within this broad area, four specific kinds of equipment and uses
were chosen for study: (1) home refrigerators and freezers; (2) mobile
air conditioners; (3) commercial chillers; and (4) food and beverage
refrigerators* These four specific uses represent over 90% of the total
emissions of F-ll, -12, -113, and -114 in the overall area of refrigera-
tion and air conditioning*
Home Refrigerators and Freezers
Current home refrigeration systems (refrigerators, freezers, ice
makers, and dehumidifiers) are well-engineered hermetic units for which
extensive practical efforts have been made by the manufacturer to mini-
mize chlorofluorocarbon emissions (R-12) over the life of the product.
Current best manufacturing practice includes the use of silver brazed
joints, special transition joints for attaching aluminum and copper tubing,
proper design to eliminate vibration from the motor-compressor unit, di-
rect connection of components over the shortest practical distances, and
relatively thick wall tubing* Manufacturers pressure test components prior
to assembly and insist on thorough in-house quality control programs uti-
lizing highly trained production personnel.
Losses from the current systems appear to be minimal for normal
operation (i.e., excluding accidental damage) during their lifetimes.
Additional engineering developments are not likely to produce a major
reduction of the emissions from this source, and the benefit would not
appear to be commensurate with the probable costs*
Service repair practices in the field vary widely depending on the
individual, repair tools and apparatus available, prior training and ex-
perience, equipment to be serviced, etc* One common practice found in
the field is to vent to the atmosphere any remaining refrigerant in the
home unit. There is no attempt to salvage the refrigerant because of (1)
fear of possible refrigerant contamination and subsequent damage to the
unit, and (2) unfavorable economics for which servicing costs outweigh
the dollar value of the refrigerant.
No new operating and/or maintenance practices within the refrigeration
industry to reduce refrigerant emissions were found* The practice of atmo-
spheric venting of small amounts of refrigerant in home units will probably
continue in the near future*
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No new developments in reclamation and/or recycling of refrigerants
is foreseen in the near future. Present large-scale technology is adequate
but under-utilized.
Mobile Air Conditioning
Previous studies on chlorofluorocarbon use and emissions indicate
that mobile air conditioning is both the largest user and emission source
among the refrigeration end-use applications* Annual emissions are divided
between major leaks, minor leaks, service-related purging, and disposal
of old systems* Minor leak sources, which frequently occur and account
for the majority of current emissions, include: the compressor shaft
seal, hose permeation, compressor gaskets and fittings* The major leak
sources, which seldom occur but contribute significant emissions because
the entire refrigerant charge is lost, include auto accidents, hose
bursts, fatigue of metal lines and compressor failures. Service related
emissions include venting any charge which remains in the system to the
atmosphere by service shops and "do-it-yourself" addition of refrigerant
which can contribute to emissions by postponing needed repairs* Salvage
yards indicate that only 25 to 50% of air-conditioned automobiles received
have any charge remaining in their systems.
Improvements in hardware component design and use which might reduce
emissions include tighter specifications for and quality of compressor
shaft seals, increased development and use of hoses with low permeation
liners or substitution of flexible metal hoses, Improved gasket materials,
and better inspection of line fittings during assembly and use. Improve-
ments in the basic system design include the addition of component isola-
tion valves, reducing the number of and improving the design of gasket
and compressor joints, and using brazed joints to connect components when-
ever possible. A major design change would be the development of a hermetic
system.
Possible changes in operating, service, and disposal procedures in-
clude periodic operation of the compressor during long periods of nonuse,
elimination of do-it-yourself recharging kits, better leak detection by
service shops, elimination of unnecessary purging, and institution of
refrigerant recovery procedures when servicing or scrapping systems. Re-
covery and recycling of refrigerant from mobile air conditioners is tech-
nically feasible but rarely practiced because of economics.
Chiller Systems
The total number of chiller units in operation is relatively small
compared to the overall number of air-conditioning units. The importance
II-3
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of this area, however, lies not in the number of units, but in the•rela-
tively large refrigerant charge of each unit. This large charge has the
potential for emission of considerable quantities of refrigerant to the
atmosphere in a single incident.
In terms of mechanical equipment, pressure relief valves offer the
greatest potential for the total loss of the refrigerant charge in a
single incident. These devices are required by building codes as safety
measures. Two types of pressure relief valves are commonly used: a rup-
ture disc device and a mechanical spring-valve arrangement. Both of these
devices can occasionally release refrigerant at pressures below the rated
pressure and, in addition, can be sources of continual low-level leakages.
The solution to the problem appears to be in better quality control rather
than in the development of a new relief valve. Purge systems (low-pressure
units only) are a continual source of refrigerant emissions. Reduced air
leakage into the low pressure units would result in less frequent purging.
More efficient purge systems can be developed which would decrease refrig-
erant emissions by at least 67% at an estimated cost for the new purge
of about three times that of the present one. However, the current cost
of the purge system is relatively small compared to the overall cost of
the system. Sources of continual, low-level leakage are gaskets, valves,
compressor seals, and flanged joints. In general, detection of leakages
at these sources and prompt replacement of the defective part would re-
duce emissions to a considerable extent. In certain instances, new types
of equipment could be installed for basically the same cost as present
equipment.
Service and repair operations are a source of considerable delib-
erate emissions of refrigerant to the atmosphere. Recovery and recycling
systems are available but, as with the other areas of refrigeration and
air conditioning, economic considerations are important.
Commercial Food and Beverage Systems
The majority of the present state-of-the-art commercial refrigeration
systems (utilizing R-22 and R-502) employ a single condensing unit connected
in parallel to one or more refrigerators having identical utilization. The
total refrigeration systems for large supermarket operations are well-
designed to minimize refrigerant losses, but, because of the overall com-
plexity of the system, many potential emission points exist. These include
failure or pinhole leaks at welded or brazed joints (including transition
joints, fittings, and elbows), isolation valves, head gasket plates on
the semihermetic motor-compressor units, and condenser and evaporator
failure, etc.
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Old refrigeration systems (utilizing R-12) for large supermarkets
are usually "compounded" operations in which one large compressor and
one small compressor are arranged in parallel and serve several display
cases, coolers, and freezers through a complicated system of valves,
piping, and a common condenser* Because of inherent design complexities
in these systems, the previous comments regarding potential refrigerant
emissions sources are equally valid*
Older refrigeration systems for small stores often rely on a number
of individual belted, open-compressors serving three or four display cases,
coolers, or freezers. Sources of refrigerant emissions include the com-
pressor crankshaft seals, the cylinder head gasket, various isolation and
purge valves, and vibration sensitive joints and seals, etc. These older
commercial systems often have an unneccesarily large number of joints,
fittings, and valves as the result of growth by addition of more display
cases.
The trend in commercial food and beverage refrigeration is to convert
older operations to modern systems using separate R-22 and R-502 systems.
Alternatively, older small stores may remodel and employ a series of R-12 her-
metic, self-contained refrigeration cases. Either choice leads to a reduc-
tion in refrigerant emissions. Conversion costs are substantial, however,
and are generally passed on to the consumer.
No comprehensive new engineering developments to reduce refrigerant
emissions in commercial food and beverage refrigeration systems are fore-
seen in the near future. Improvements will continue to unfold slowly on
a broad front as component manufacturers improve their product lines.
Service repair practices in the field vary with the age, size, and
complexity of the commercial refrigeration systems. Generally speaking,
the problem area will be located and isolated, thereby defining a limited
quantity of refrigerant to be purged to the atmosphere or possibly sal-
vaged for recycling. Methods for the recovery of small quantities of used
refrigerant are currently available. Large scale systems for the recycling
and storage of used refrigerant are available at a cost of $ 15,000 to
120,000.
FOAM BLOWING AGENTS
The 1975 consumption of chlorofluorocarbons as blowing agents in
plastic foams is estimated at 80 to 84 million pounds, roughly 9% of the
total U.S. production. Flexible and rigid urethane foams account for more
than 90% of total usage of chlorofluorocarbons as blowing agents. While
rigid foams consume over 70%, direct atmospheric emissions from flexible
II-5
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foams are three to four times greater than direct losses from rigid ure-
thane foams. The reason for this diparity is that blowing agents are largely
retained within rigid foams, while virtually all chlorofluorocarbons used
in flexible foams promptly diffuse into the atmosphere.
There are presently no emission controls employed to collect and treat
chlorofluorocarbon vapors evolved in producing plastic foams. A survey of
(1) major foam producers, (2) suppliers of foam ingredients, (3) foam
production equipment manufacturers, and (4) solvent vapor recovery or
emission control purveyors indicates that, not only is there no chloro-
fluoro carbon control technology in present use, but there has been little
or no consideration given to the possible need for any type of control.
Much of the basic information that would be required for the design
and development of chlorofluorocarbon vapor recovery systems has not yet
been collected. Among the most critical data needed are:
* How much blowing agent is lost from foams at various stages or
steps in production?
* What are the rates of chlorofluorocarbon diffusion out of foams
over the period of generation and subsequent processing?
* Where are the best locations for the collection of blowing agent
vapors with least complication of commercial production?
* What are the current levels of chlorofluorocarbon vapor concen-
trations at various points along the processing sequence; and
the existing concentrations in the present ventilation and ex-
haust air systems?
* And perhaps of greatest importance—Can significant fractions
of the chlorofluorocarbon vapors be collected using sufficiently
low rates of air flow to make vapor recovery less costly?
Only one or two persons among the experts surveyed could even ven-
ture estimates regarding these unknown factors. Among foam producers,
only one company reported recent (July 1976) attempts to measure chloro-
fluorocarbon levels throughout the foam line and exhaust air. Clearly
it will be necessary to obtain actual analytical data of the type indi-
cated. This needs to be done before detailed evaluations can be made of
either the technical feasibility of chlorofluorocarbon recovery, or the
effectiveness of any proposed control system in reducing emissions to the
atmosphere. All of these engineering aspects should be clarified before
additional economic assessments can be performed.
II-6
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This study, therefore, has attempted to ascertain the extent to which
it may be feasible to control chlorofluorocarbon emissions in foam pro-
duction. For the urethane foams, each of the major production processes
was'^examined.__Those features of each process that affect the consumption
and losses of blowing agent were identified and discussed. For six major
types of foam processes, a representative "model plant" has been defined
in terms of mass balance, processing steps and estimated losses of blow-
ing agents. For each of the six major processes, the approximate distribu-
tion of chlorofluorocarbon losses at various stages of production has
been compared.
Of the existing solvent vapor control processes, only activated bed
adsorption appears technically suitable for recovering chlorofluorocarbon
vapors, at relatively low concentrations, from fairly high volume air
streams, there are a few problems specifically related to the chemical
and physical properties of the vapors to be treated; but none that pose
serious obstacles to the use of this established technology. Carbon adsorp-
tion systems regularly exhibit recoveries of 93 to 98% of the solvent vapors
passed through the sorbent beds.
If sorption systems were applied for recovery-of chlorofluorocarbons
from various stages of plastic foam production, it should be possible to
reduce total foam plant emissions by 49% up to 75% of present losses.
Fo.r flexible urethane foams, the recovered chlorofluorocarbons represent
a corresponding reduction in total blowing agent purchases. In the case
of rigid foams, only 9 to 15% of total chlorofluorocarbon consumption
could be recovered.
Preliminary economic analysis shows that savings due to chlorofluoro-
carbon recovery may exceed total annualized costs for recovering fairly
large quantities of blowing agent vapors. Similarly, favorable ratios of
savings to cost are attainable for recovering moderate amounts of chloro-
fluorocarbon vapors using automatic packaged sorption units.
CLEANING AND DRYING SOLVENTS
These applications represent areas in which the chlorofluorocarbons
play a relatively minor role both with respect to the total quantity of
solvents used and to the overall consumption of chlorofluorocarbons among
the use areas. The consumption of F-113 and F-ll in this application rep-
resents only approximately 6% of the total solvents used for cleaning and
only about 9% of the total consumption of the five chlorofluorocarbons.
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The use of F-113 and F-ll in the cleaning and drying field is con-
centrated in the electrical and electronics industries for the defluxing
of printed circuit boards (PCB's) and the cleaning of electronic parts,
electric motors, and delicate electronic and scientific instruments. As
a dry-cleaning agent, F-113 is used primarily in coin-operated type machines
run by trained personnel. The general public has little contact with F-113
as a dry-cleaning solvent.
For cleaning and drying applications, other than dry-cleaning, the
major sources of solvent emission are evaporation, dragout, and used sol-
vent disposal. The specific quantity of solvent loss attributable to each
source is dependent upon the configuration of the part being cleaned or
dried. The methods of emission control considered were carbon adsorption
systems, increased freeboard height, freeboard chillers, refrigerated
freeboard chillers, covers, and offset-sump systems. Distillation equip-
ment was considered for the recycling of used solvent. Operating practices
were found to be an important factor in the quantity of solvent lost by
evaporation and dragout.
The efficiency of each method of emission control has been estimated.
These efficiencies range from approximately 35 to 65% dependent upon the
specific method. All of the identified emission control methods, except
carbon adsorption and used solvent distillation, .are directed towards a
reduction in the quantity of solvent lost from the machine. Almost all
of the methods are shown to be economically feasible because* the calcu-
lated savings/cost ratios are greater than 1.0, which is the break-even
point. The use of covers and an increased freeboard height show the largest
economic advantage.
Carbon adsorption systems are designed to collect and recover solvent
vapor from the atmosphere immediately above the machine. Adsorption effi-
ciencies of the carbon bed are approximately 95% for F-113 so that the
overall system efficiency depends upon the solvent vapor capture effi-
ciency. Azeotropic mixtures containing water-soluble components cannot
be recovered by this method. Distillation of used solvent can be easily
accomplished and was found to be economically feasible. Solvent recovery
by distillation of the order of 85 to 90% can be obtained. More careful
adherence to good operating procedures can also be effective in reducing
solvent loss, but because this area concerns human nature, it is difficult
to assign any specific efficiency for reduction of emissions.
The dry-cleaning industry represents an area where a very costly
solvent (F-113) competes with two low-cost solvents. Systems utilizing
F-113 are, of necessity, carfully designed to minimize solvent loss in
order for the use of F-113 to remain competitive.
II-8
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SECTION III
REFRIGERATION AND AIR CONDITIONING
This section of the report addresses the sources of refrigerant emis-
sions and the technical and economic aspects of emission control methods,
including service operations and refrigerant recovery techniques* The dis-
cussion is specifically concerned with those systems employing R-ll, R-12,
R-113, and R-114 in the following classifications of the refrigeration
and air conditioning sector:
1. Home refrigerators and freezers,
2. Mobile air conditioning,
3. Industrial centrifugal and reciprocating chillers, and
4. Commercial food and beverage refrigeration*
Other areas of refrigerant usage, such as home (room and central) and r '
small commercial air conditioning systems, commonly employ other re-
frigerants and thus are excluded from consideration in this study.
According to a published report, the entire area of refrigeration
and air conditioning accounts for 26% of the total, chlorofluorocarbon
emissions from end-use applications. Within the total area of refrigera-
tion and air conditioning, mobile air conditioning accounts for 33.37.
of the total emissions. Industrial centrifugal and reciprocating chillers
account for 22.8% and food store and beverage refrigeration contributes
14.5%. Both of these figures include contributions from R-22 emissions.
Home refrigerators and freezers contribute 2.27. of the total refrigera-
tion and air conditioning emissions. Other types of equipment either em-
ploy refrigerants outside the scope of this study or contribute less than
1% of the total emissions in this end-use area^i'
Because the units considered in this section are mechanical sys-
tems presenting several probable sources of refrigerant emissions which
vary in leakage intensity from unit to unit, it is not possible to quan-
tify the amount of emissions from specific point sources in any terms
III-l
-------
other than major or minor* To our knowledge, few, if any, studies have
been conducted which attempt to quantify an average leakage from specific
point sources* Many specifications are stated but the actual performance
of a specific part or material under operating conditions is not well
established.
In the following subsections concerning each of the four refrigera-
tion and air conditioning systems, the sources of refrigerant emissions
and the technical and economic aspects of emission control techniques
will be discussed for each system.
HOME REFRIGERATORS AND FREEZERS
The total home refrigeration market is nearly 10 million units in-
cluding imports (approximately 0.8 to 0.9 million). Market saturation
is virtually complete for refrigerators (*•* 100%) with replacement sales
nearly 80% of total sales. The home freezer market is far from saturation
(~ 45%) but growing as consumers continue to take advantage of seasonal
prices and purchase foodstuffs for future use. Replacement sales are like-
wise growing and amount to an estimated 38% of total freezer sales.^~°'
The refrigerator consumer market is dominated by GE/Hotpoint, Whirl-
pool, and White (Westinghouse) which jointly account for 68% of all re-
tail sales. The freezer consumer market is dominated by White (Westinghouse)
and Whirlpool and account for 53% of total retail sales. A published sum-
mary lists all manufacturers and their market shares.jL/
The home refrigeration industry consists of approximately 10 large
manufacturing companies and perhaps a thousand component manufacturers,
wholesalers, and distributors. The test equipment and service and repair
industry of some 300,000 individuals serves this economic sector. The
total economic value of the entire refrigeration industry including pe-
ripheral suppliers and the service industry probably is $10 billion an-
nually.6,7/ This is close to 0.6% of the Gross National Product.
Estimated Refrigerant in Use and Annual Losses
The total amount of R-12 refrigerant in the home refrigerator and
freezer sector is probably in the range of 85 + 10 million pounds. This
calculation is based on an estimated 73 million homes having at least
one refrigerator and an estimated 32 million homes having at least one
freezer, and the additional assumption of 0.63 and 1.25 Ib of refrigerant
per unit for refrigerators and freezers, respectively.^./
The current replacement sales rate of approximately 81% of annual
refrigerator sales and a corresponding 38% replacement rate for freezers
III-2
-------
permits an estimate of 4.6 million refrigerators and 1.14 million freez-
ers which could be discarded in 1976. However, it is not uncommon for
the "old" refrigerator to be placed in a.basement or garage for addi-
tional storage purposes. Using the above figures, approximately 4.3 mil-
lion pounds of refrigerant are potentially available for release to the
environment either through gradual leakage or catastrophic rupture as
in scrapping of the unit.
Refrigerator and freezer average lifetimes have been extended as
the product line improves. Current estimated average lifetimes before
replacement for standard-sized refrigerators is about 15 years, whereas
the compact refrigerators have an average lifetime of approximately 10
years. For freezers, the average lifetimes are 18 years for the standard
size and 12 years for the compact size*!/
Refrigerators are discarded for many reasons, some of which are not
related to refrigerant loss, and a high percentage of discarded units
may arrive at a disposal center (dump) with a full charge of refrigerant
which can be suddenly released if the unit is crushed for scrap or buried
in a landfill. In essence, the total potential of 4.3 million pounds of
refrigerant annually discarded probably does enter the atmosphere each
year. No attempt is made to salvage and recycle even the recoverable por-
tion of this quantity since the average home refrigeration unit contains
much less than f1.00 worth of refrigerant.
Other home refrigeration units using chlorofluorocarbons falling
within the scope of this report include dehumidifiers and ice makers.
The combined market for these units is approximately 10 to 15% of the
refrigerator market&&I The total refrigerant charge of scrapped de-
humidifiers and water coolers in 1976 is estimated to be 0.2 +0.1 mil-
lion pounds*?./ Hence, the total annual available refrigerant charge for
release into the atmosphere during discard or scrapping operations of
major home appliances is approximately 4.5 million pounds, principally
as R-12.
Table III-l presents a summary of estimated major home appliance
refrigerant usage as original and replacement charge for 1976.
III-3
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Table III-l. HOME REFRIGERATION USAGE AND REPLACEMENT IN 1976
Major
appliance
Units
shipped
in 1976
(million)
Original
charge
million
(lb)
Unit
replacement
sales
(million)
Average
unit
charge
(Ib/unit)
Total
replacement
charge
(million lb)
Refrigerator 5.7 3.6
Freezers 3.0 3.8
Dehumidifiers 0.48 0.4
Ice makers 0.15 0.3
Total 8.1
4.6
1.14
0.16
0.03
0.63
1.25
0.48
2.00
Source: References 4 through 6 and 8.
From a macroeconomic viewpoint, due to the relatively long history
of consumer refrigeration in the United States, an approximate "steady
state" condition has been achieved between production and consumption
(or discard) of refrigeration units. Although .in any given year, e.g.,
in 1976 some 8.1 million pounds of chlorofluorocarbons will be used in
producing new consumer refrigeration units, some 4.5 million pounds or
** 56% of the refrigerant will be "discarded" or have the potential for
release into the environment via leakage, catastrophic failure, scrap-
ping and/or landfill operations.
Sources of Refrigerant Emissions
The present hermetically sealed home refrigerator or freezer con-
sists of a single unit in which the motor, compressor, condensing and
evaporating coils, and various other components are assembled in such
a manner as to provide a leak-proof system with a minimum number of
joints. The adjective "leak-proof" is relative and depends on the de-
gree of sophistication of the test method, e.g., pressure- and/or
bubble-immersion tests,: E. I. du Pont de Nemours Dytel® organic dye
technique, the halide- torch, electronic halogen leak checker, and mass
spectrometric techniques including the use of helium gas, etc. Generally
speaking, the less sophisticated techniques are more prevalent. The
pressure/bubble tests are used more often than the more sensitive elec-
tronic halogen leak detector or the highly refined mass spectrometric
techniques.
Figure III-l presents a schematic diagram of current hermetic home
refrigeration or freezer systems. The various arrows indicate potential
refrigerant emission points.
III-4
-------
DOUBLE TUBE'
HEAT EXCHANGER!
CAPILLARY TUBE —3
Source: Adapted from Whirlpool Corporation refrigeration products ser-
vice manual*
Figure III-l. Typical hermetically sealed home refrigeration unit
III-5
-------
The major refrigerator manufacturers, Whirlpool Corporation, Amana
Corporation, GE/Hotpoint Company, etc., internally manufacture some or
all of the motor-compressor housing units, heat exchangers, condenser
and evaporation coils, fans, cabinets and doors, plastic and rubber com-
ponents, and insulation.
These companies heavily rely on subcontractors for some or all of
their motor-compressor units, valves, tubing, electrical controls, tran-
sition joints, gaskets and seals, insulation components, rupture discs,
refrigerant, and service and repair equipment and supplies.
Some condensing units are placed in the bottom of the refrigerator
or freezer cabinet along with the motor/compressor hermetic unit. The
condenser is either a simple convection type (static condenser) or a
forced convection type (blower condenser).
The evaporator is generally made of aluminum and provides the basic
volume for frozen food storage, ice making, and general cooling of the
entire refrigerator or freezer cabinet. Connections between the evap-
orator, condenser, and the motor-compressor are either aluminum or cop-
per tubing which is silver brazed or helium-arc welded. Various other
components, i.e., the starting relay switch, protective fuses, tempera-
ture sensing devices, defrosting heater coils, door switch, etc., com-
plete the system. The complete refrigerant circulating system is designed
to be removed in one piece for servicing convenience.
Refrigerator and freezer manufacturers generally pressure test (with
and without immersion) system components prior to assembly through in-
house quality control programs. After brazing and assembly, the entire
system is pressure tested. If the system appears satisfactory, it is
filled with the proper refrigerant charge and leak-checked during an
initial break-in period. Only satisfactory systems are finally installed
in refrigerator and freezer cabinets. Unsatisfactory systems are re-
worked and re-checked with a leak detector for satisfactory performance.
By use of an intensive quality control program, relatively few defects
are found after refrigerant is placed in the system. Industry-wide
re-work rate is of the order of 0.5%«2jJ^2/
The common emission sources, denoted by numbered arrows in Figure
III-l, correspond to the following:
1, Rupture of evaporator due to accidental puncture, corrosion or
flaw in the component.
III-6
-------
2. Failure at a brazed joint (various potential locations) due to
corrosion, faulty brazing technique, excessive vibration, physical abuse,
flaws, etc. Particularly troublesome are the copper/aluminum transition
joints between the aluminum evaporator and copper lines*
3. Accidentally broken capillary tube.
4. Failure of a connecting line due to a flaw or high pressure in
the flow system.
5. Leakage from a manufacturer's process tube (pig-tail).
6. Leakage from the point on a line where a service (saddle) valve
had been installed by service repairmen in the field.
In hermetically sealed units, all joints are silver brazed and/or
helium-arc welded. Service valves may or may not be present depending
upon the manufacturer.
Current refrigeration manufacturing technology, e.g., at the Whirl-
pool and Amana Corporations, specifies the use of silver brazed joints
or helium-arc welded aluminum tubing, direct connection of the various
components over the shortest practical distances using relatively thick
wall tubing, and no service valves. The compressor and motor are sealed
in a common housing thus eliminating the compressor crankshaft seal which
has been a particularly troublesome emission point.
»
Older refrigeration assembly techniques included various flanged
joints or mechanical compression seals, conventional soft solder, and
flanged service valves. The Schrader valve, which is basically an auto-
motive tire valve fitted with special chlorofluorocarbon resistant gas-
kets, seals or 0-rings, and a gasketed valve cap, is still used on some
refrigeration equipment but not on the standard hermetically sealed re-
frigeration units. These valves are common sources of leakage. Soft
solder joints tend to fail due to vibration and/or corrosion and have
long been discontinued.
The causes of low refrigerant level in hermetically sealed units
include all of the above categories; the most frequent categories are
the aluminum/copper transition joint, any joints associated with the
high pressure side of the motor-compressor,unit, and corrosion of the
aluminum evaporator. Physical damage to the unit by sharp objects such
as ice picks being improperly used still occur. No statistical data base
exists at present to rank the various categories.
Ill-7
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Service and Repair Operations - It is not known exactly how many air
conditioning and refrigeration service repairmen there are in the United
States today. The U.*S,' Department of Labor indicates there were about
135,000 air conditioning, refrigeration, and heating installation and
repairmen employed in 1972, most of which were employed by cooling and
heating dealers and contractorsJLi/ It is felt that these data are low
and data from other^ sources have been usedJtZ/
There were approximately 3,000 service repair establishments with
payrolls amounting to $305 million annually in 1972 and employing 10,274
persons,^/ The largest concentration of service shops appear in New York
State, California, and Texas. Regionally, the South accounts for 417. of
the service shops* An independent industry source estimates there are
perhaps 50,000 to 75,000 self-employed service repairmen (independent
jobbers).!/
Table III-2 estimates the number of service repairmen in various
employee categories. This information was compiled from various sources
and is the best estimate obtainable of the total work force capable of
installing and servicing refrigeration and air conditioning systems.
Table III-2. AIR CONDITIONING AND REFRIGERATION
SERVICE REPAIRMEN IN THE U.S. IN 1976 BY CATEGORY
Estimated No. of Reference
Worker category service repairmen source .
Self-employed 50,000-75,000 13
Service repair establishment 10,274 12
employees (2,868 fix-it shops
with payrolls)
Manufacturers, wholesalers, 7,500-15,000 6
distributors, and retail
store employees (local,
regional, and national)
Commercial and industrial service 2,000-3,000 6, 14
organization employees
Contractor and builder employees 200,000-250,000 6, 47
Total service repairmen 270,000-353,000
III-8
-------
Regarding service repair practices for home refrigeration, much de-
pends on individual training and preference in handling various kinds
of refrigerant leakage problems. Factory-trained servicemen (e.g.,
Carrier Corporation, Whirlpool Corporation, etc*) are supplied with ser-
vice manuals and procedures for specific brands and models of equipment.
Independent service repairmen may not possess this kind of information
and will proceed to repair a leak based on individual experience with
varying kinds of equipment.
In general, service repairmen are hesitant to salvage refrigerant
for direct recycling unless they are certain it is not contaminated
with water, oil, greases, dirt and dust, finely-dispersed solids, nor
partly decomposed due to;compressor burn-out. The service repairman
does have the option of collecting any remaining refrigerant for re-
processing by distillation.
In the opinion of several industry spokesmen, few attempts are ever
made by service repairmen to recover refrigerants from small systems
such as would be found in the home. The reason for the present practice
of venting small quantities of refrigerant to the atmosphere is economics.
Each home refrigeration unit (refrigerator, freezer, dehumidifier or ice
maker) contains 0.6 to 2.0 Ib of refrigerant per unit and has an intrinsic
value of only $0.40 to $1.20. The cost of placing a service repairman in
the field together with test equipment, tools, repair kits and apparatus,
etc., is approximately $25.00/hr in 1976.J-Z/ If 30 min time.is required
for transfer, labor charges are $12.50.
Methodologies to Reduce Losses
Hardware Improvement - Several manufacturers of home refrigeration units',
as well as component manufacturers and service repair shops, were con-
tacted to inquire of methodologies, e.g., hardware improvement, new op-
erating or maintenance practices and procedures, etc., to reduce and/or
eliminate refrigerant losses in the field. Invariably, these sources con-
sidered the present hermetically sealed system to be "near perfect." The
rationale of this position is that the home refrigeration system has
evolved over the past 50 years with engineering emphasis being placed
on the development of the motor-compressor single-housed unit, the de-
velopment of superior motor insulation and gasketing materials, increased
use of brazed joints, improved engineering design, newer refrigerants, etc.
The present manufacturing philosophy is to avoid complicated system
designs and any extra or unnecessary connections or service valves. No
new major developments are immediately foreseen by manufacturers with
regard to refrigerant losses in the field.
Ill-9
-------
Recent improvements in hardware design to reduce refrigerant losses
include proper engineering design of the total refrigeration system to
eliminate or reduce known potential trouble spots, including shorter con-
nectors, fewer fittings, heavier wall aluminum and copper tubing, etc*
In addition, product improvement has been accomplished through manu-
facturing quality control testing programs, better trained manufacturing
personnel, and improved leak detection techniques at the point of manu-
facture, including leak testing prior to and after final assembly.
Whirlpool Corporation has conducted an engineering cost feasibility
study to replace chlorofluorocarbon-blown insulating material with a
vacuum-Perlite combination insulation for refrigerators and freezers.2'
Through actual construction of vacuum-Perlite test panels and installa-
tion, sufficient technical information was attained for a critical assess-
ment of the project. An insulating value of 5/8 in. thick vacuum-Perlite
combination was equivalent to a 3 in. thickness of Fiberglas®. However,
technical difficulties were encountered in the filling process. The project
is inactive at the present time.
No engineering development cost feasibility studies to reduce re-
frigerant emissions from hermetic systems have been found. This is not
to be interpreted as meaning that such engineering development cost
studies do not actually exist, but rather that manufacturing companies
or component manufacturers guard these developments closely. Although
leakages from hermetic systems are considered small problems, new de-
velopments could provide a competitive advantage. One industry spokes-
man suggested that if such studies had been completed by a refrigeration
company which pointed to positive conclusions regarding design and/or
operating practice changes for a product line, such a company would not'
prematurely reveal this event for it could lead to loss of a potential
competitive advantageJ^./
Thus, the home refrigeration industry is in an apparent "stand-pat"
stance although it is quite possible some positive changes in product
performance and improvement in refrigerant losses may be forthcoming
in the near future.
Present industry.hardware research and development efforts are in
the direction of reduction of energy consumption for the same cooling
capacity. A recent Compressor technology Conference at Purdue University
brought forth a series of compressor efficiency and performance papers
related to energy consumption.19-21/
III-10
-------
Whirlpool Corporation and Amana Corporation are both considering
installation of alarms or electronic consoles with self-diagnosing cir-
cuits and indicators to warn the consumer of low refrigerant level, ex-
cessive heating and pressure surges, etc. Such alarm systems will be
doubly costly to the consumer since the research and development costs
will tend to be passed on to the buyer and the alarm systems consume
additional electrical energy; however, these costs will be partially
balanced by early detection of equipment malfunction*
Operating and/or Maintenance Practices - No new operating and/or main-
tenance practices or procedures within the refrigeration industry to re-
duce refrigerant emissions were found* Industry.spokesmen prefer to em-
phasize adherence to manufacturer's manuals for recommendations regarding
operation and maintenance of home refrigeration units*
A standard reference book for refrigeration and air conditioning
directs the repairmen to purge the system; of refrigerant prior to ser-
vicing*^/ A service manual from a large refrigeration manufacturer also
directs purging of the refrigerant to the atmosphere with no recommenda-
tion for recovery* In contrast, a recent article in Air Conditioning and
Heating News describes simple equipment and techniques for recycling re-
frigerant from domestic refrigeration units after servicing the equip-
ment.^/ However, in the opinion of the authors of this report, the ar-
ticle merely constitutes "wishful thinking" in discussing recovery and
recycling techniques of home refrigerants. Such practices in the field
would not be attempted due to poor economics as previously described.
. *
Small leaks in hermetically sealed systems are frequently ignored
as being uneconomical to repair. It may be difficult to educate owners
of home refrigeration systems to check for small leakages. A built-in
detection system such as the E. I. du Font Dytel® organic dye technique
may be quite useful. However, some type of incentive would be required
to encourage owners to periodically check their units for leakages.
Vibration may be a cause or contribute to a fatigue failure and a
catastrophic failure resulting in a loss of the refrigerant charge. The
service repairman should check for excessive vibration and insure that
the unit is level.
Recovery and Recycling Systems for Refrigerants - If the recovery and re-
cycling of refrigerant from home refrigerators were to become mandatory
by law. in spite of the unfavorable economics, there must be rapid and
convenient techniques and apparatus available. Refrigerant R-12 can be
transferred by pressurizing the system and capturing the refrigerant in
a cooled refrigerant cylinder. Several companies supply refrigerant han-
dling and measuring equipment*^/ One type of recovery system is avail-
able for approximately $700.J£/
III-ll
-------
Another possible recovery method would involve the use of a stain-
less steel gas cylinder (e.g., DOT "G" cylinder) equipped with a pres-
sure gauge and a transfer pump, which most service companies have avail-
able. A "G" cylinder can be purchased for less than $200. If it is as-
sumed that an average refrigerator in need of service contains 0.5 Ib
of R-12, up to 30 refrigerators could be emptied using the same recovery
cylinder. It is doubtful that a serviceman would repair more than five
to six refrigerators in a single day. For safety reasons, this method
should be used only by personnel thoroughly familiar with gas transfer
procedures. The gas in the cylinders should be emptied at the end of
each day.
The E. I. du Pont Company has developed a refrigerant reclamation
systems for either R-12 or R-22 for use by original refrigeration unit
manufacturers.^' The equipment removes oil, solid contaminants, mois-
ture, and noncondensibles from the contaminated refrigerant by pumping
the fluid through a series of vaporization steps, traps, condensers,
and driers. The basic unit cost is approximately $10,000. It is claimed
the savings resulting from the equipment installation will earn back the
investment in a reasonable (unspecified) period. Figure III-2 illustrates
the basic features of the refrigerant reclaimer. The standard design does
not include a storage vessel. An air operated diaphragm pump transfers
the clean dry refrigerant back to the manufacturer's plant refrigerant
storage tank. Piping from rework areas to the reclaimer and from the re-
claimer to storage is the customer's responsibility. The total cost to
the customer^is approximately $'15,000 to $20,000 for the basic unit,
storage vessel, piping, additional pumps, and other accessories.^.' Only
one basic reclamation unit has been sold by Ou Pont Company to date. -
The E. I. du Pont Company has also developed an F-ll solvent clean-
ing system for large scale refrigeration systems with burned-out compres-
sor units. The procedure directs the user to discharge the contaminated
refrigerant to the open atmosphere. Fresh F-ll is circulated through por-
tions of the system by a .diaphragm pump which develops a strong pulsating
action to mechanically scrub and scour interior system surfaces. The F-ll
used for cleaning can be recycled, especially if a strainer and filter-
drier have been used in the solvent return line. The cleaning system costs
between $850 to $onf)25/ and is available from an independent company,
F. F. Slocomb Corporation.
MOBILE AIR CONDITIONING
An estimated 45 million mobile air conditioning units were in ser-
vice in 1973. These were primarily factory-installed auto air condi-
tioners, but also included air conditioning installation in light trucks,
III-12
-------
Refrigerant!
ToBej
Reworked
CO
Lzi
Vaporizing
Coil!
! Condensing^
[Unit:
-Tj Level,
J llndicatorj
L
Oil & Solids
Trap
Transfer Compressor!
and Pressure,
Switch Control,
I Automatic Purge i
System and Pressure'
| Relief Valve I
j Refrigerant-Cooled
{Condenser'
Level
~H Control
I Filter
i Drier
| Pump |
To Bulk
Moisture
llndicator
|T~^ — H Storage
U !
Vessel
Sources Adapted from E. I. du Pont Refrigerant Product Information Bulletin RT-58.
Figure III-2. Refrigerant reclamation system
-------
jsj* busses, and add-on air conditioners. It was also estimated that
7.53 million new mobile air conditioner units were installed and 7.00
million units were scrapped in 1973. All of these units used R-12 ex-
cept for those in busses and some RV's which may use R-22.J:/ Estimates
for succeeding years are not complete. Data for factory-installed auto
air conditioners indicate that although the installation rate declined
from 7.3 million units in 1973 to 5.6 million units in 1974, and to 4.9
million units in 1975, the percentage of new cars equipped with air con-
ditioning has remained nearly constant, with 73.8% of 1973 models, 68.2%
of 1974 models, and 72.2% of 1975 models being factory equipped.^./ In
effect, neither the trend toward smaller cars, a heightened desire to
conserve energy nor concern for chlorofluorocarbon emissions have dampened
the popularity of one of the auto industry's most expensive options. If
the production decline of new cars because of the economic recession was
accompanied by a similar decline in the scrappage rate, approximately
47 million mobile air conditioners are in use at this time. By compari-
son, an estimated 105 million total automobiles and 25 million other
vehicles are presently in use«2?_/ Therefore, about 40% of all registered
motor vehicles in the United States are air conditioned.
Mobile air conditioning contributes to the large economic impact
of the automotive industry. In 1974, the automotive and related manu-
facturing was estimated to be an $85 billion per year industry*=Z/ The
dollar amount which is directly attributable to auto air conditioning
is not exactly known. Factory installed air conditioning, which usually
adds $400 to $500 to the selling price of new cars, would account for
about $2.5 billion for new car sales of about $28 billion.
Mobile air conditioning also has a large employment impact. In 1972,
there were 3,826 establishments with 1.3 million employees engaged in
automotive-related manufacturing, 67,654 establishments with 0.5 million
employees engaged in wholesale automotive-related sales, 328,206 estab-
lishments with 1.9 million employees engaged in automotive-related re-
tailing, and 168,959 establishments with 0.5 million employees engaged
in automotive-related servicing»±Z/ No information could be found which
specifically identified the proportion of establishments or employees
directly engaged in mobile air conditioning activities. It has been esti-
mated that approximately 507. of the 200,0004- service stations in the
United States also engage in mobile air conditioning service activities
of various types»22/
The most recent comprehensive estimates on chlorofluorocarbon use
and emissions available for mobile air conditioning were made for 1973.J:'
* Recreational vehicles.
111-14
-------
From the A. D. Little report, it is calculated that the refrigerant pres-
ent in the 45 million units would total 171 million pounds if all were
fully charged.
Charging of new units produced during 1973 required 28.6 million
pounds of refrigerant, and, from calculations based on the A. D. Little
data, replacement of that lost through leakage or service required 44.3
million pounds for mobile air conditioning.i/ This results in an esti-
mated net addition of 72.9 million pounds of refrigerant per year. This
estimate compares favorably with one auto manufacturer's estimate that
the average mobile air conditioner unit uses the equivalent of three full
charges during its useful life, i.e., one initial charge and two replace-
ment charges .22J
Nonrecoverable basic leakage resulted in an estimated 6.8 million
pounds of refrigerant emissions^:/ Potentially preventable leakage due
to design and servicing-related procedures was responsible for an esti-
mated 42.8 million pounds of refrigerant emissions..!/ Finally, it was
estimated that 21.3 million pounds were lost during the disposal of
scrapped units .A/ This results in 70.9 million pounds of refrigerant
emitted into the atmosphere in 1973. The net result is an increase of
2 million pounds of refrigerant per year, based on 72.9 million pounds
added and 70.9 million pounds emitted.
The estimated 70.9 million pounds of refrigerant emitted*by mobile
air conditioning is 33.3% of the total emissions of chlorofluorocarbons
used in refrigeration applications. If the refrigeration applications
which exclusively use R-22 are eliminated from consideration, then mobile
air conditioning accounts for 43.8% of the chlorofluorocarbon emissions
of interest in this study. In either case, mobile air conditioning is
the largest chlorofluorocarbon emission source among the refrigeration
applications.^/
The overall estimate for refrigerant usage is probably still rep-
resentative of current initial and replacement charging practices. Al-
though the amount of refrigerant used for new unit charges has declined
along with the decline in automotive production recently, this has prob-
ably been offset by a rise in replacement usage as people utilize mobile
air conditioning for a longer time before salvaging vehicles. A number
of auto salvagers estimated that only 25 to 50% of the cars with air
conditioning still have a charge when scrapped.^/ Therefore, the pub-
lished estimate of refrigerant lost at disposal!/ would be reduced by
about 10 million pounds.
Ill-15
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The evaluation of chlorofluorcarbon emission control in mobile air
conditioning end-product applications presented in this section consists
of data acquired from various levels of the industry. Information sources
include automobile manufacturers, add-on system manufacturers, component
suppliers, parts suppliers, material suppliers, installers and servicers
of mobile air conditioner units, suppliers of equipment which might be
used to recover and/or recycle refrigerants, and trade organizations.
The following subsections present an" evaluation of emission sources,
service practices, and methods which might be employed to reduce emis-
sions through hardware improvements, changes in maintenance procedures,
and recovery and recycling systems.
Emission Sources
A typical mobile air conditioning system is shown in Figure III-3.
This system consists of a compressor mounted on, and driven by, the ve-
hicle engine, a condenser, a combination filter-dryer-receiver unit, an
expansion valve, and an evaporator. Most system components are connected
by metal tubes and fittings. However, flexible hoses are used to connect
the compressor to the system and isolate engine vibrations.
The sources of chlorofluorocarbon emission can usually be divided
into two groups: (1) minor leaks which cause the air conditioning system
to operate progressively less efficient because of the gradual loss of
the refrigerant charge, and (2) major leaks which result in the complete
loss of the refrigerant charge in a short period of time and cause the
system to cease operation. »
From discussions with numerous manufacturers and service companies,
the following sources of leakage (and their magnitudes) were commonly
quoted. The minor leaks which most frequently cause refrigerant losses
and eventual servicing of the mobile air conditioning system are:
a. The compressor shaft seal
b. Hose permeation
c. Compressor gaskets
d. Fittings
Major leaks which occasionally occur and necessitate immediate ser-
vicing of the system are caused by:
a. Auto accidents
b. Hose bursts (due to abnormal operating conditions)
III-16
-------
CONDENSER-
TYPICAL
LINE FITTING-
TYPICAL
HOSE FITTING
C
C
\
FILTER-DRIER-RECEIVER
EXPANSION VALVE
Figure III-3. Typical mobile air conditioning system
-------
c. Fatigue of metal lines
d. Compressor failure
Although the major leak sources result in the complete loss of the
refrigerant charge, they are relatively rare occurrences, whereas all
mobile air conditioners experience one or more of the minor leak sources.
Consequently, it is felt that the cumulative total emissions from the
minor sources are probably many times the total from the major sources.
Also, the major leak sources are largely unpredictable and therefore dif-
ficult to eliminate by design or material changes. The minor leaks, on
the other hand, are well-known emission sources which could be quite
predictable although little quantitative data were found. The remainder
of this subsection presents a qualitative analysis of the emission sources
and quantitative data which were obtained.
Shaft Seal - The compressor shaft seal is the most frequently mentioned
leak source although the exact magnitude of the leakage from the shaft
seal is largely unknown. Engineering specifications for the shaft seal
vary from 1/2 oz per year at one compressor manufacturers^/ to 5 oz per
year at one automotive manufacturer.^./ Detection of leakage during as-
sembly of the system is made by using electronic leak detectors or by
doping the refrigerant with a small amount of helium and using a helium
detector.
The compressor shaft seal actually consists of two seals—one dy-
namic rotating seal and one static nonrotating seal. The dynamic seal
consists of a set of rubbing elements, one of which is mounted on and
rotatin'g with the compressor shaft and the other which is a nonrotating
element mounted in the compressor housing and spring-loaded against the
rotating element. One rubbing element is typically a lapped cast iron
plate while the other rubbing element is a ceramic material such as
aluminum oxide or sintered carbon graphite. The ceramic element must be
impregnated with a nonpermeable material to prevent diffusion of re-
frigerant through the element. The static seal is usually an 0-ring
which is mounted between the nonrotating element and the housing to al-
low axial movement of the element while preventing leakage between the
housing and the nonrotating element. Leakage may occur past either the
0-ring or the rubbing interface, although the rubbing interface is usu-
ally thought to be the worse of the t«n.36/ Another source felt that the
static seal contributed equally to the total leakage.^5./ Permeation
through the ceramic rubbing element can also be a shaft seal-related
leakage source.
111-18
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Manufacturing tolerances and surface finishes play important roles
in the seal effectiveness* The cast iron plate must be lapped flat and
.typically a flatness of 23 x 10~6 in. is specified.^/ Also, over 800
types and grades of ceramic material are available for the other rubbing
element* Therefore, proper selection of the material is important.
Operating conditions are important, particularly during the winter
months when the refrigeration oils can gum up the surfaces of the rubbing
elements if the system is not operated periodically. This causes high
friction and temperature to be generated when the sysetm is started, re-
sulting in seal damage.
Hoses - Permeation of refrigerant through the hoses used in mobile air
conditioners is difficult to evaluate although several sources indicated
that the losses are a significant source of emissions. One auto manufac-
turer specifies hose permeation rates to be less than 0.1 oz per foot
per ypar.29/ Therefore, the average mobile air conditioning system which
may have 10 ft or more of hoses could account for only about 1 oz per
year of leakage. Several other believe this value to be too low.
One hose commonly used in automobile air conditioners is lined with
butadiene-aerylonitrile copolymer elastomer, which is resistant to R-12
and to oil. The outer layers of this hose are usually another elastomer.
(polychloroprene), chosen for its weather and abrasion resistance. Data
published by Du Pont for a 1/2 in. I.D. hose of this material* indicates
negligible leakage at 75°F (24°C), 0.3 oz per foot per year at 100°F
(38°C), 3.5 oz per foot per year at 130°F (54°C). 9.1 oz per foot per
year at 160°F (71°C), 16.1 oz per foot per year at 185°F (85°C), and
30.3 oz per foot per year at 220°F (104°C).l2/ It should be noted that
the vapor pressure of the refrigerant increases from about 90 psia (6.3
kg/cm2) at 75°F (24°C) to about 524 psia (36.8 kg/cm2) at 22CPF (104°C).
From these data it is apparent that the system operating temperature and
pressure have a significant effect on the leakage rate and that a weighted
mean temperature and pressure would be necessary to accurately predict
the actual annual leakage.
Nylon hose has recently been recommended for use as an air condi-
tioning hose and is presently being used on some new car air conditioners.
Test data indicate a diffusion rate of 0.5 to 1.6 oz per foot per year
when used at a temperature of 180°F (82°C)*2i/ Table III-3 gives permea-
tion test data for four hose materials when used with refrigerants R-12.
R-22, R-500, and R-502.12-/ In these tests the nylon liner was 0.025 in.
thick and the elastomer hoses were 0.140 in. thick. All test hoses were
0.50 in. I.D. and 18 in. long. A correlation for loss rate per foot per
year versus temperature is given in Figure III-4 for NBR, CS, and nylon
hoses.
in-19
-------
32/
Table III-3. PERMEATION CONSTANTS, OIL PRESENT^
Test temperature, K x 10
Hose type
CSM
CSM
CSM
CSM
Neoprene
Neoprene
Neoprene
Neoprene
NBR
NBR
NBR
NBR
Nylon
Nylon
Nylon
Nylon
a/ D = Did
75° F
Refrigerant (24° C)
12
22
500
502
12
22
500
502
12
22
500
502
12
22
500
502
not get
„•/
D
D
D
D
4.4
1.1
0.641
D
114.5
1.14
6.57
D
0.434
D
D
through the
100° F
i (38° C)
D
3.86
D
D
2.34
5.26
2.28
1.17
0.162
U£/
5.66
9.05
D
0.596
0.00903
0.143
140° F
(60° C)
D
5.03
0.338
0.40
. 3.59
: 7.83
4.46
2.57
1.02
U
4.08
8.50
0.012
0.545
0*0168
0.127
preconditioning in
Jj/ A pressure of 800 psia was used in the
180° F
(82° C)
0.889
5.80
1.81
1.29
5.08
7.95
5.12
3.07
1.94
U
6.0
9.10
0.0223
0.63
6.0491
0.240
14 days.
220° F
(104°C)
3.52
7.ik/
3.92
1.72k/
5.92
9.06£/
7.30
3.06*>/
2.53
U
4.45
5.62^
0.0225
0.77*/
0.155
0.292b/
calculation of .the constan
£/
CSM
for R-22 and R-502. This was justified by the pressure transducer
data and extrapolation of the refrigerant pressure versus temper-
ature graph beyond the critical point.
U = Unmeasurable (too fast).
= Chlorosulphonated polyethylene (43% chlorine content)
NBR = Nitrile rubber
Permeation constants were calculated at each test temperature for
each combination of hose type and refrigerant using the following
equation:
KAP
t
— K
AP
where:
A
Source:
Observed loss rate, g/day
Inside surface area of hose
(28.25 in.2)
Absolute refrigerant pressure
(saturation pressure)
Freon Product Information RT-51, E.
and Company, Inc.
iii-20
t = Thickness of hose liner
(0.025 in. for nylon
and 0.140 in. for all
others)
K = Permeation constant,
g-in/day-lbf
I. du Pont de Nemours and
-------
10
8
6
~ I
£ :!
CO
CD .4
£-''2
« .'
co .08
O .06
.04
.02
.01
75 100 140 180 220
TEMPERATURE°F
Source: Freon® Product Information .RT-51, E. I. du Pont de
Nemours and Company, Inc^r'
Figure III-4. R-12 (with oil) loss rate versus temperature
A hypothetical calculation for a system containing R-12 in NBR
hoses and operated during typical conditions for a year is given in
Table III -4. From this calculation it is shown that the majority of
the refrigerant permeation loss in average cars occurs when the car is
not operating and the hoses are at ambient temperature. Although the
permeation rate is 'higher when the car is operating, the car is parked
many more hours than it is operating. The loss during air conditioner
operation is less than 407. of the total
Gaskets and Seals - Elastomers are extensively used for gaskets and
seals in mobile refrigeration compressors. The refrigerant and
refrigerant -oil mixtures can cause swelling of the elastomer material
and extraction of plasticizers and other agents used in the elastomer
formulation. Improper material selection can cause weakened or dimin-
ished mechanical properties which may lead to leakage by diffusion or
improper fit. Poor design or installation may also contribute to an im-
proper fit that can cause leakage. Data on the magnitude of the leaks
111-21
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Table III-4. R-12 CALCULATED LOSS RATE FROM AUTO AIR CONDITIONING SYSTEM,
NBR HOSE^' WITH R-12 AND OIL
I
N>
NJ
Avg. 200 Hr/year Avg. 400 Hr/year Avg.
hose car operating hose car operating hose 8,100 Hr/year
temp. AC operating temp. AC not operating temp. parked
'(°F) (Ib/year) (°F) (Ib/year) (°F) (Ib/year)
Discharge hose 220 0.053 100 0.007
Liquid hose 130 0.013 100 0.007
Suction hose 60 0.001 100 0.011
Total 0.067 0.025
Grand total = 0.19 Ib/year loss
50 0.029
50 0.029
50 0.043
0.101
Sources Freon8' Product Information RT-51, E. I. du Pont de Nemours and Company, Inc.
-------
through elastomer sealed or gasketed joints is unavailable. Several
sources indicated that the relative magnitude of leaks at elastomer
sealed or gasketed joints is less than at shaft seals or through hoses.
One compressor manufacturer has a specification for a leakage rate that
does not exceed 1/4 oz per year from any given point^£J while one auto
manufacturer's specification is 1/2 oz per year from any one point.^./
Measurement methods used to check the finished products against the spec-
ifications were riot Revealed.
Fittings - Several sources mentioned line fittings as potential leak
sources. However, most believed that properly selected and installed
fittings cause a minimum of leakage. Adherance to installation torque
specifications is the most important method to minimize or eliminate
leaks at fittings according to one source,2!/ while periodic retighten-
ing checks to detect fittings loosened by vibration was recommended by
another*34/ In either case, it was acknowledged that fittings can and
do leak, but the leakage rate or contribution to total refrigerant emis-
sions is unknown.
Hose fittings are similar to line fittings except that one of the
joined sections is an elastomer refrigerant hose. Although the metal to
metal connections of the fittings are no worse than other line fittings,
the portion of the fitting connected to.the hose is a problem area and
frequent emission source. These fittings normally use a crimped assembly
technique to join the hose and fitting and must form a good mechanical
joint in-addition to containing the refrigerant. Typical leakage rates
or the contribution to total emissions is unknown*
The cumulative losses from all minor leak -sources is estimated by
various sources to range from several ounces to 1/2 Ib or more per year
for an average mobile air conditioner unit.
In addition to the annual leakage from the minor leak sources, some
mobile air conditioning units develop failure which cause the entire
charge to be lost.
Accidents
Automobile accidents can cause the loss of the air conditioner re-
frigerant charge by rupturing a portion of the system. The most frequent
source is the condensor coil which is mounted in front of the radiator
and is quite vulnerable in any accident with front-end damage. Metal con-
necting lines can also be bent and broken to release the charge. Although
total release of charge is an obvious source of refrigerant emissions,
no statistical data were found that give the number of accidents result-
ing in refrigerant loss. Several auto salvage yards indicated that only
III-23
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25 to 50% of the air-conditioned cars scrapped have a refrigerant charge
remaining and that many of the cars without charges have been involved
in accidents.£2/
Hoses - Hose bursts, which occur occasionally and cause a complete loss
of the refrigerant charge, can result from a number of causes such as
improper material selection, malfunction of some other component in the
system which results in excessive internal pressure, damage from outside
sources, vibration, deterioration with age, and manufacturing or assembly
defects* Design and manufacture-related causes are usually quickly dis-
cerned and remedied, whereas the use and operation-related hose failures
are difficult to predict or eliminate.
Line Fatigue - Fatigue of metal lines is a vibration-related failure that
can also occur and result in the complete loss of the refrigerant charge.
According to repair shops, this type of failure seems to be design-related;
a few certain makes, years, and models of automotive air conditioner sys-
tems are prone to this type of failure, while most others are rarely af-
fected.
Compressor Failure - Occasionally the malfunction of the mobile air con-
ditioning compressor will result in the cracking of the compressor case,
head, or other components; this then allows the complete loss of a re-
frigerant charge. This type of failure is believed by some sources to
usually be caused by insufficient lubrication which in turn may be caused
by the loss of oil along with refrigerant at other leakage points in the
system*£_L' This type of failure may also result from the mechanical fail-
ure of the compressor components. The number of compressor failures which
cause the emission of the refrigerant charge is not known, but is esti-
mated to be relatively small.
In addition to the emission sources just discussed, significant quan-
tities of refrigerant are vented to the atmosphere during servicing and
repair of mobile air conditioning systems.
Service Practices
Present maintenance and service practices for mobile air conditioning
systems were found to vary greatly. Most minor leaks are tolerated by the
unit owner until the system performance declines (cold air output dimin-
ishes) and necessitates the repair of the system and/or the addition of
refrigerant. Usually the latter is chosen and refrigerant is added to
restore the system performance without any repair being undertaken.
111-24
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Frequently the refrigerant is added by the vehicle owner using
readily available charging kits and small 13 to 16 oz cans of refrig-
erant. The charging kit consists of a flexible hose with a Schrader valve
on one end and a valve assembly which attaches tp and pierces the refrig-
erant can on the other end* The charging kit sells for $3 to $6 and the
refrigerant sells for about $1.50 per can* If properly used, it allows
safe and economical replacement of lost refrigerant* If improperly used,
charging kits can be dangerous and may explode if connected to the wrong
service valve on the air conditioner system* In either case, repairs
which may be needed are delayed and chlorofluorocarbon emissions will
continue to occur from the system*
If the unit owner does not use a do-it-yourself charging kit. he
will most likely take the unit to a service station or general repair
shop. About 507o of the service stations and most general repair shops
engage in some form of mobile air conditioner service work* Many of
these simply add refrigerant and check for leaks. The refrigerant is
usually added through a manifold-gage set which allows monitoring of
pressures at various points in the air conditioning system and aids in
diagnosis of system problems. Leaks may be detected by observing pres-
sure changes on the manifold gages, visual observation of oil escaping
with the refrigerant at leak points, or by using leak detectors such as
halide torches, if they are available. Many of the service stations and
general repair shops engaged in air conditioning servicing only add re-
frigerant and perform diagnostic checks while offering little, if any,
additional air conditioning service. Also there are many shops which
purge partially charged systems before recharging the system to the factory
specifications. This procedure only increases the emission problems. The
more difficult repairs are referred to large dealer service shops and
air conditioning specialty shops.
The larger dealer service shops and air conditioning specialty shops
tend to have sensitive leak detectors and the specialized equipment nec-
essary to offer complete and competent repair service. Consequently,
those shops receive the more difficult cases which are not repairable
by the unit owner or general repair shops and service stations. Prior
to any servicing which requires opening of the system, all remaining re-
frigerant is blown into- the atmosphere without any attempt for recovery
or recycling of the used charge. Many of the systems which must be opened
still contain all or nearly all of their refrigerant charge. Failures
of components such as the expansion valve, or compressor jams, or plugging
of internal passages within the system require opening of the system for
repair and result in large quantitites of chlorofluorcarbons being re-
leased into the atmosphere. The frequency of these types of failures and
the resultant emissions during servicing are not known, but the intentional
release of refrigerant to the atmosphere is believed to be a significant
emission source*
III-25
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Methods of Reducing Emissions
This section presents and examines the technical feasibility, cost, ,
and effectiveness of reducing or eliminating environmental contamination
from mobile air conditioning systems by improving hardware, by improving
operating and maintenance practice, and by instituting recovery and re-
cycling programs.
Hardware - Prospective hardware changes fall into three general catego-
ries: (1) improvement of selected parts and components', (2) general re-
design of the complete system, and (3) radical redesign of the system*
Improvement of selected components such as the compressor shaft seal,
flexible hoses, gaskets and fittings, which are responsible for large
quantities of refrigerant emissions when their cumulative effects are
considered, would result in the most immediate benefits.
The compressor shaft seal presently contributes approximately one
dollar to the $30 to $40 cost of the total compressor. Shaft seals have
been greatly improved since the introduction of mobile air conditioners,
and seal manufacturers believe that present seals represent the near
ultimate state of the art. Surface finish, porosity, and tolerance of
the seal components are the primary concerns of the seal designer. One
seal component manufacturer stated that there are 800 to 900 types and
grades of seal materials available to the designer, but the cost variation
between materials is probably only plus or minus 10%.35 / of greater in-
fluence on the seal cost are the physical configurations of the seal
components and the manufacturing tolerances which can cause up to 500%
variation in the cost of the finished seal. One seal manufacturer re-
ported they use random* sample quality control techniques such as given
in MIL-Std 105 to determine the acceptance quality level of each lot
rather than inspect each finished seal.
It appears that tighter tolerances and more rigorous inspections
would reduce subsequent emissions. This would cause higher reject rates
and consequently increase the cost of the acceptable seals by a factor
of 2 to 3 if acceptable output were cut in half. One manufacturer is re-
portedly developing a phenolic material to replace ceramic and sintered
material now in use with the hope of eliminating porosity problems.^./
An estimated cost of a seal made from this material was not available.
In general, the seal manufacturers concede that a leak-proof compressor
shaft seal is not possible.
Prospective hose changes fall into two groups: (1) improved mate-
rials for substitution in existing elastomer hose designs, and (2) re-
placement with flexible metal hoses. One industry source believes that
III-26
-------
Teflon® -Lined hoses would have a very low leak rate and retain the vi-
bration isolation advantage of present system designs which utilize elas-
tomer hoses. Unfortunately, the source also stated that reliable fittings
for use with Teflon® -lined hoses were not available for the pressures
and temperatures encountered in mobile air conditioner systems*^/ No
permeation data were obtained for Teflon® -lined hoses although they are
used for many applications where chemical resistance is important. Develop-
ment of suitable fittings should be technically feasible but costs are un-
known. Development of a multilayer hose might be a feasible alternative
if the Teflon® could be sandwiched between layers of conventional hose
materials to serve as a refrigerant barrier. It is estimated that such
a hose would probably cost 50 to 100% more than presently used hoses.
Increasing the wall thickness of present hoses might also reduce refrig-
erate permeation and would increase costs in proportion to the thickness
increase.
Flexible metal hoses are a frequently mentioned alternative to con-
ventional hoses. These were reportedly used on one make of car in the
1950*8, but were quickly abandoned because of vibration-induced fatigue
cracks that caused loss of refrigerant. It is not known if any air con-
ditioner manufacturers have evaluated flexible metal hoses recently, but
improvements in metal hose designs--particularly in the aerospace programs-
might make them a candidate for reconsideration. Cost is also a hinderance
to the introduction of flexible metal hoses. A typical 4 ft length of
elastomer hose with conventional fittings costs about $10, a similar
hose with special fittings or other features costs in the $20 to $30 range
while flexible metal hoses would cost in the $35 to $45 range.41,42/ since
mobile air conditioners contain at least two flexible hoses, the cost in-
crease due to flexible metal hoses would probably be $30 to $60 per unit.
Many prospective component changes could be retrofitted to existing
mobile air conditioners when making repairs or they could be integrated
into present production systems with a minimum of difficulty once sub-
stitute parts are developed and made available. General redesign of the
system, however, may not be as easily incorporated into present systems.
Changes which might be included in a general redesign of the system
where the major components remain relatively unchanged are: (1) the addi-
tion of isolation valves; (2) reducing the number and improving gasketed
compressor joints; and (3) changing from mechanical joints to brazed joints
when possible.
The present mobile air conditioner systems generally do not contain
isolation valves, although one automobile manufacturer, which uses pre-
charged air conditioner components, has valves incorporated into some
of the line connections. The addition of isolation valves would enable
111-27
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service repairmen to repair a portion of the system without venting the
entire or remaining refrigerant charge into the atmosphere. As a minimum,
two valves could be installed to isolate the compressor and additional
valves would make isolation of other major components possible* The esti-
mated increased costs are $1 to $2 for each valve plus a similar amount
for labor. One possible problem with isolation valves is that the valve
stem and fittings could become additional leak sources.
Reducing the number and improving gasketed compressor joints would
be a technically feasible method to reduce emissions; however, no design
studies have been made. This would require significant redesign of the
compressor unit and tooling changes. Generalized compressor studies by
one automotive engineer indicate that $20 to $30 million would be required
for retooling, with a minimum of 3 years to production.^./ These figures
assume that shaft seals would be allowed.
Changing mechanical joints to brazed joints would eliminate fitting
leaks, although it may pose some assembly and repair problems. In gen-
eral, brazed joints have been found to be more reliable and to cost less
than mechanical fittings when used on household refrigerators and freezers.
This might also apply to mobile air conditioners. However, household ap-
pliances are brazed before being installed in their cabinets while mobile
air conditioners would probably have to be brazed after installation in
their vehicle. Additional study and redesign would need to be undertaken
to determine the feasibility of using brazed joints to connect mobile
components,
One automotive engineer summarized his comments on the improvement
of existing systems as follows:
"In the short term, modest reductions in leakage appear
obtainable through increased leak detection and quality con-
trol efforts during manufacturing and assembly. In the long
term, design revisions to reduce leakage may be feasible (re-
duced number of fittings, better hose materials, revised manu-
facture and assembly procedures, and better leak detection
equipment). These efforts would increase manufacturing costs."21'
These comments were also representative of other contacts in the
automotive industry.
The most often mentioned radical system redesign is the development
of a hermetic mobile air conditioner. One automotive engineer commented
that a hermetically sealed system would require a direct current electric
motor developing up to 7 h.p. to compete with today's cooling rates. The
power generation equipment to supply this electric motor and the motor
III-28
-------
itself would pose a tremendous packaging problem without a major vehicle
redes ign.,29./ Another automotive engineer had the following comments &rJ.'
1. "The addition of an electric motor and associated power
conversion equipment and the increased size of the alternator to
provide the required A/C power would impose significant weight
and cost penalties,"
2. "To provide equivalent cooling performance, the A/C
power requirement would be approximately quadrupled due to the
two additional stages of energy conversion required between
the engine shaft and the compressor, and the efficiency of
power conversion equipment. It thus seriously negates the
mandated requirement of improving fuel economy of our products."
A reply from a compressor manufacturer indicated that a hermetic
unit is technically feasible, that it would add about $ 150 to the pres-
ent cost of automotive air conditioning, it would allow the unit to be
moved away from the engine compartments high temperature environment,
and that some research and development work on hermetic automotive units
had been undertaken*^.'
Further investigation into the power requirements show that present
automotive alternators generate the electrical equivalent of 3/4 to 1-
1/2 h.p. Therefore, an electrically driven mobile air conditioner would
require an alternator with 5 to 10 times the electrical output of pres-
ent alternators. Although the physical size and cost would probably not
be increased at the same rate as power output, the cost increase to the
consumer would still be substantial. The retooling cost would be much
greater than the 120 to $30 million estimate reported for generalized
compressors of conventional design.
Another type of hermetic drive available would be magnetic cou-
plings*ftft/ This type of drive uses rotating magnets on the outside of
a thin-walled tube to drive similar magnets on the inside of the tube
and essentially transmit power through the tube wall. The size and cost
of a system to drive mobile air conditioner compressors is not known.
The refrigerant pressure on the inner tube surface may limit the fea-
sibility of this type of hermetic drive.
Operating and Maintenance Practices - Changes in operating and mainte-
nance practices generally fall into two groups: (1) owner-oriented
changes, and (2) service shop-oriented changes. The owner-oriented
changes are increased education to operate the system periodically dur-
ing the winter months and elimination of do-it-yourself changing kits.
Elimination of the do-it-yourself kits was recommended by a number of
111-29
-------
sources because recharging of a nonparforming or leaking system merely
prolongs the problem*
Mobile air conditioner manufacturers recommend that their units be
operated periodically during the off season to prevent the shaft seal
from drying out or gumming up. Failure to do so causes high friction and
temperatures when the system is first started the next cooling season.
This can cause damage to the shaft seal and result in premature failure
and excessive emissions. To eliminate the need for periodic starting,
one automobile manufacturer has introduced compressors which rotate the
compressor shaft and seal whenever the engine is running.
The service shop-oriented changes are the elimination of unnecessary
system purges and recharging, and better leak detection. Since the most
frequent symptom for needed air conditioning service is a low refrigerant
charge, many air conditioner locations simply recharge the system, much
as the do-it-yourself owner would do, and perform no repairs to remedy
the problem. Some servicers reportedly purge any remaining charge from
the system prior to recharging. Indiscriminent purging and recharging
should be eliminated.
Many servicers of mobile air conditioning equipment do not have leak
detection equipment available or have only moderately sensitive detectors
such as halide torches. Wide spread use of the more sensitive electronic
leak detectors or mixing a dye (e.g., Dytel® ) in the refrigerant would
aid in better leak diagnosis and help prevent the recharging of systems
with excessive leaks. Electronic leak detectors with sensitivities suit-
able for detecting small leaks cost in the $1,000 to $2,000 range. Less
sensitive units are available for as little as $100.
Recovery and Recycling - Presently, very little recovery equipment is
available. No United States automobile manufacturer attempts to recover
refrigerant from the defective systems found on the production lines nor
do any service shops prior to servicing systems in use.
One assembly plant in Mexico reportedly uses a 7-1/2 h.p. condens-
ing system to remove refrigerant from defective air conditioners prior
to reworking.^/ The unit cost is about $18,000 and has been in use 3 to
4 years.
According to one automotive engineeri~Z/
"Recovery and recycling of R-12 at the manufacturing plant
appears feasible. Aeronutronic-Ford Corporation has designed and
is in the process of installing a recovery and recycling system
to be used in conjunction with leak test facilities for refrig-
eration system components."
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Smaller systems suitable for refrigerant recovery in service shops have
been estimated by a number of sources to cost from $300 to $1,000 or
more, depending upon the degree of recovery required and the size of the
systems and components used for recovery. Several simple systems are pos-
sible such as purging into an evacuated tank or using a chilled tank*
These are not feasible for high volume service shops or production lines
and would require the eventual transfer of the collected refrigerant to
other tanks.
Nearly all sources contacted would not recommend the direct recy-
cling of recovered refrigerant back into air conditioner systems because
of the possible contamination which might be present and the unknown per-
centage of oil in the recovered mixture. Distillation of the used refrig-
erant would be required before it could be acceptable for reuse. Distil-
lation of R-12 used in mobile air conditioners is probably beyond the
capabilities of most service shops; they would have to rely upon an out-
side distilling service. According to an industry source, companies are
reported to purchase used refrigerant for distilling, but no financial
details are knownJt^./
One refrigerant producer has designed and is offering for sale an
OEM refrigerant reclaimer system capable of removing and reprocessing
up to 90 Ib/hr of refrigerant for reuse. The cost of this system is re-
ported to be $7,500 without storage tanks^24/
Auto salvagers face recovery problems similar to those encountered
by service shops. However, since salvagers would have no potential for
recycling refrigerant, a market or approved disposal system for the re-
covered refrigerant would be needed.
One automotive engineer summarized refrigerant recovery with the
following commentst^Z/
"Refrigerant could be recovered during service and when a
vehicle is being scrapped with technology now available. The re-
covery and storage equipment is not available, however, and
would require time for development. An economic incentive may be
necessary to promote the use of recovery techinques during ser-
vice, repair, and scrap operations."
These comments were also typical of other contacts throughout the
automotive, service, and salvage industries; however, since recovery
and storage equipment are presently available, but not widely used, the
time required for development of new systems would not be needed.
Ill-31
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CHILLER SYSTEMS
Chiller systems are often referred to as "secondary refrigeration
systems" because one refrigerant is used to cool a second refrigerant,.
which in turn is used to cool the building or enclosure. These units
are large scale systems used in the air conditioning of industrial or
commercial buildings* Their use in these applications, as opposed to
a single refrigerant system, is because it is easier and more effici-
ent to pump a cooled liquid (water or brine) long distances than it is
cold air.
A published report stated that in 1973, a total of 271,000 chiller
units were in operation in the United States or had been shipped.^' Of
this number, about 54,000 were centrifugal compressor chillers and
217,000 were reciprocating compressor chillers. The importance of these
systems with respect to chlorofluorocarbon emission lies not' in the total
number of units, but rather in the quantity of refrigerant charge per
unit. According to the A. 0. Little report, the average charge per cen-
trifugal unit is 2,500 Ib while a reciprocating system holds an average
of 350 lb*i' A manufacturer has recently estimated the average charge
per centrifugal unit at 1,635 Ib and a reciprocating system at 137 Ib.z2'
These two systems accounted for an estimated 33.9 million pounds in an-
nual emissions or about 24% of the total emissions in the area of re-
frigeration and air conditioning J:/ These latter two figures include
contribution by R-22 in addition to the refrigerants of interest to this
study.
*
The major manufacturers of chiller units are Carrier, Trane, York,
Westinghouse, and Airtemp (Fedders). These five companies control about
807. of the large unit market JtJL/
In the following parts of this subsection, discussions will be de-
voted to the basic system design, sources of refrigerant emission, and
potential methods of emission control.
Basic System Design
The basic difference between reciprocating chillers and centrifugal
chillers is in the type of compressor being used and, hence, the refrig-
eration capacity of the two systems. Reciprocating compressors operate
on the principle of a piston traveling back and forth in a cylinder.
These units are used in applications up to approximately 100 tons re-
frigeration capacity. Reciprocating compressors can be used for capa-
cities greater than 100 tons, but above this level the centrifugal com-
pressors are more efficient and are commonly employed. Centrifugal
compressors, in which an impeller rotates within a housing, draws in
vapor and discharges it at a high velocity causing compression by cen-
trifugal force.
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In terms of refrigerant usage, the older, open-type reciprocating
compressor systems are high pressure units, employing essentially 100%
R-12, A vast majority of the new reciprocating systems presently on the
market are hermetic or semihermetic units using R-22.JJL/ For centrifugal
compressor systems, lower tonnage units (up to 1,000 tons) commonly use
R-ll; intermediate tonnage (1,000 to 5,000) units use either R-12 or
sometimes R-114; high tonnage (5,000 to 15,000) systems use R-22 as the
refrigerant. These tonnage figures are approximate and should not be
interpreted as a clear line of demarcation* At times, R-113 and R-ll are
employed in hermetic centrifugal chiller systems having 80- to 500-.ton
eapac-H-y.8,45/
As would be expected, the refrigerant capacities of these units
varies considerably with the tonnage. A 20-ton reciprocating unit has
a primary refrigerant charge of about 40 to 50 Ib, whereas a 60-ton
unit holds approximately 150 to 200 Ib. For centrifugal chillers, a
100-ton unit has a refrigerant charge of about 400 to 500 Ib, Because
of improvements in system design, the refrigerant charges of new cen-
trifugal units have been reduced to about 60% of that of the older
units.4!/
Aside from the secondary refrigeration system, the design of 'chil-
ler units is basically the same as that for the vapor compression cycle
used in other air conditioning systems, but the scale is much larger. A
simplified composite design for a chiller unit is shown in Figure III-5.
A
High-—
Pressure
Liquid
Experaion-»JL
Low——«
Pressure
Liquid
Warm Warer-*
Figure III-5. Composite diagram of chiller systems
111-33
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As shown in the figure, the primary refrigerant (chlorofluorcarbon) in
these chiller systems is used to cool a secondary refrigerant, water
or brine, which is then circulated to cool the building or enclosure.
This figure is a composite in that it does not represent a specific chil-
ler system but contains components found in both low and high pressure
systems. For example, purge systems are necessary only for a low pres-
sure (R-ll or R-113) centrifugal chiller system so for a high pressure
(R-12) unit, the purge system would be absent. An air cooling system can
be used instead of a cooling tower. As shown, the compressor-motor
arrangement implies an open-shaft reciprocating or open-drive centrifugal
system. In a semi-hermetic or hermetic system, the compressor and motor
would be combined into a single unit and not separated as shown. The
average lifetime of a chiller system, either reciprocating or centrifugal,
is about 20 years.4..5?46/
All reciprocating compressor systems are high pressure units. In
the past, R-12 was used almost exclusively in these units. It has been
stated that there is no valid reason why a reciprocating compressor
chiller unit needs to use R-12; in fact, almost all of the new units
employ the use of R-22 except possibly for low temperature applications.
R-22 provides approximately 607. more cooling capacity than an R-12
unit J^.' Existing R-12 units could, technically, be converted to R-22
units. One source states that this conversion would involve installing
a completely new condensing unit, changing all in-line pressure valves,
expansion valve, and other parts to accommodate the higher pressures
employed in a R-22 system. Such a conversion would be costly, but it is
technically feasible. For a small 5-ton unit, converion would cost ap-
proximately $2,000 per unit; for a 7.5-ton unit, approximately $3,000^-2.'
Another source states that the conversion can be accomplished more simply
and at a lower cost«l§/ Multiple small units are often found in office
buildings, etc., to provide more control over the cooling than one large
unit.
Chiller manufacturers generally construct the basic hardware of
their systems, including the raw castings, oil pumps, motors, and other
fabricated equipment. Typical components purchased from subcontractors
or suppliers include compressors, relief valves, electrical controls
and components, gaskets, seals, refrigerant, and numerous small hardware
items.4*/
Sources of Refrigerant Emission
The major sources of refrigerant emission in chiller systems can
be attributed to primarily two generalized areas: (1) leakages due to
mechanical or equipment malfunctions, and (2) service and repair opera-
tions. Of the total refrigerant consumption for these two purposes, it
111-34
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has been estimated that approximately 75% of the total is used to re-
plenish refrigerant lost due to leakage and 25% is consumed to replace
fluid discarded during service and repair operations.—' A published
report has stated that 75% of the total refrigerant leakage (excluding
disposal) in centrifugal and reciprocating chillers is preventable
through relatively minor modifications to current equipment design or
service procedures and 25% of the leakage is due to nonrecoverable
leakages..!/ The report provides no clarification with respect to which
leakages are considered to be preventable or nonrecoverable.
An industry source has stated that one manufacturer has provided
data on leakage rates for a centrifugal chiller JLZ/ The manufacturer
stated that for R-ll systems, about 1.1% of the charge is lost due to
minor leaks (joints, components, etc.) and approximately 0.2 to 1.0% is
lost due to shipping problems, damage to refrigerant lines during opera-
tion or repair, and deliberate release to the atmosphere. For high pres-
sure R-12 systems, the leakage rate due to minor leaks is approximately
3.1% and ranged from 0.25 to 1.3% for leakage due to shipping, line
damage, and deliberate release. The manufacturer was unable to estimate
how much refrigerant is lost to the atmosphere when the machine is opened
for service.
Refrigerant emissions and equipment failure are basically uniform
with respect to geographical location. The midwestern part of the United
States, i.e., the Plains States, seems to encounter equipment problems
before other geographical areas. Since high humidity has a greater ef-
fect on the "load" of a system than temperature, perhaps the combination
of high summer temperatures and high humidity are a factor in early fail-
ures.^/ One failure that is geographically oriented is with the use of
air-cooled condenser systems. In coastal areas, these condenser systems
are much more susceptible to corrosion problems, due to the salt water
in the air, than in other areas of the country.
Emissions Due to Leakage - The most common service call is due to low
refrigerant levels resulting from the leakages to be discussed in this
subsection. According to a nationwide refrigeration and air conditioning
service company^/ and manufacturers of chiller systems^L^iI§/ the major
sources of leakage in these large systems are as follows:
* Pressure relief valves and rupture discs;
* Purge systems (low-pressure centrifugal units only);
* Compressor shaft seals;
* Gaskets; and
* Miscellaneous minor sources.
111-35
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Of these types of leakage, pressure relief valves and purge systems,
are sources of large leaks, which can result in the emission of sig-
nificant quantities of refrigerant to the atmosphere with a single mal-
function. Line breakages or cracks and leaks through gaskets, seals, and
faulty solder joints will emit small quantities of refrigerant at any
one time but the continual leakage over a period of time can result in
the loss of significant quantities.
Figures III-6 and III-7 are photographs of chiller systems in pres-
ent usage at Midwest Research Institute (MEI). These systems are for il-
lustrative purposes only and the presence of any tradenames or general
recognition of the units is not intended to be an endorsement of a par-
ticular product.
Figure III-6 shows typical sources of leakage from a centrifugal
chiller system. The sources, designated by numbered arrows, are as
follows:
1. Oil dash pot;
2. Gasket on refrigerant loading arm;
3. Pressure rupture disc—vented to the atmosphere;
«.
4. Gasket on refrigerant sight glass;
5. Purge system;
6. Gasket on Venturi chamber;
7. Gaskets on two flanged joints on refrigerant equalizing line; and
8. Hose on the oil return line.
In Figure III-7, the numbered arrows show the potential sources of
refrigerant leakage in a reciprocating chiller system. In this illustra-
tion, the sources are delineated as follows:
1. Gasket on hand valve; .
2. Flange gasket;
3. Gasket on hand valve;
4. Expansion valve;
III-36
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H
M
M
I
'
Figure III-6. Centrifugal chiller system
-------
13
• ••
Figure III-7. Reciprocating chiller system
111-38
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5. Gasket on hand valve;
6, Gasket on condenser;
7. Valve cap gasket—high pressure side of compressor;
8. Compressor shaft seal (hidden);
9. Flange on high pressure side discharge line of compressor;
10, Flange on high pressure side discharge line of compressor;
11. Valve cap gasket—low pressure side of compressor;
12. Gasket on condenser; and
13. Flange on low pressure side discharge line of compressor.
The compressor shaft seal (Arrow 8) is hidden from view in this photo-
graph by the rounded metal shield over the shaft from the electric mo-
tor (lower left hand corner with two metal rings on top) to the com-
pressor. Immediately below Arrow 8 is a bolted plate to provide access
to the lower portion of the compressor for inspection and repair of
connecting -rods, crankshaft, and other components* The gasket on this
plate is a potential source of refrigerant leakage as is the gasket on
the bolted compressor head immediately below Arrov 9. This particular
compressor has six cylinders so that other compressor heads are located -,
atop the machine between the two discharge lines and on the hidden side
of the machine.
Pressure relief valvesft£/ - The function of pressure relief valves
is to release refrigerant in the event of excessive pressure increase
because of some emergency, such as fire or equipment malfunction, so
that the entire system will not explode. These valves are required by
building codes for pressure vessels rated at 15 Ib or more. The code
also requires that these valves be vented to the atmosphere.
There are basically two types of pressure relief valves: mechani-
cal and rupture. Rupture discs are either of the carbon type or the lead
type. Mechanical pressure relief valves are used on high pressure (R-12)
systems, whereas the rupture disc valves are employed on low pressure
(R-ll, R-113) centrifugal machines. The basic problem with mechanical
pressure relief valves is that once the valve relieves excess pressure,
it has a tendency to leak until replaced) reseating is also a problem.
Obviously, the valves are not designed in this manner but, in practice,
failure to reseat is a common fault. The placement of the mechanical
111-39
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relief values in the system can also lead to refrigerant loss* In recip-
rocating chillers, these valves are commonly placed on the condenser
but the system is designed to operate fairly close to the burst pressure
of the condenser* Thus leakages from this arrangement are rather common-
place.
Carbon or lead rupture, discs appear to have a two-fold problem:
initial leakage around or through the disc and. with age, premature
rupture at pressures lower than the rated pressure. When a rupture disc
bursts, the entire charge of refrigerant can be lost to the atmosphere.
It is generally conceded that sooner or later, nearly all of the discs
will leak within their normal lifetime of about 2 years. Another problem
can arise as a result of air leaks into low pressure systems. When the
unit is shut down, the purge is not operating. Air can leak into the sys-
tem. Upon starting the unit, the purge system cannot instantaneously re-
move the air so that the refrigerant pressure plus the air can exceed
the pressure rating (14.5 to 15.5 Ib) of the disc and result in its
rupture.
In previous units, some rupture discs were backed up with a mechan-
ical pressure relief valve, but this arrangement can lead to a dangerous
situation. If air leaks between the two valves, a small pressure will
build.JSince the rupture disc operates on a pressure differential basis,
an abnormally high ^pressure in the system could result before the pres-
sure differential would rupture the disc. If the mechanical valve is
placed in front (on the machine side) of the rupture disc, this problem
probably would be eliminated.
A recent example of the magnitude of refrigerant loss due to mal-
functions of pressure relief valves can be cited. Kansas City Interna-
tional Airport uses centrifugal chiller systems with a unit charge of
about 15,000 Ib of refrigerant (R-12). A pressure relief valve on a unit
there malfunctioned at a pressure below the rated pressure and released
over 10,000 Ib of the refrigerant into the atmosphere.
Purge systems - Purge systems are installed only on low pressure
(R-ll) centrifugal units. Since these units operate at low pressure, it
is necessary to remove air, due to leaks, from the refrigerant. These
systems are probably the major source of continual refrigerant emission
from low-pressure units to the atmosphere. The primary difficulty with
the present purge systems is that they are not very efficient in the
separation of the air from the refrigerant, resulting in a loss of the
refrigerant along with the air. All purge systems have these problems.^/
It has been stated that from approximately 3 to 5 Ib of refrigerant are
lost for each pound of air removed from the unit JtSlZS' Not all purge
units operate in the same manner but they are all based on the principle
III-40
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of pressure differential* For some units, a float-valve arrangement is
used to periodically release the air to the atmosphere .^§.7 Other sys-
tems use a compressor arrangement whereby the air is continually re-
leased to the atmosphere^./ With the float -valve arrangement, one of
the operational problems is due to the floats on the valves sticking
and allowing excess refrigerant to pass with the air. the problem with
the floats is caused by an accumulation of particulates, oils, and
other contaminants removed from the refrigerant Jt§./ With all systems,
if the purge pump has carbon piston rings, considerable backside leak-
age will
Compressor shaft sealsZJ/ - Shaft seals are present on reciprocat-
ing chillers and some centrifugal units (open-drive systems). Seal leak-
age is one of the more common leakage problems but represents a gradual
loss of refrigerant rather than a large single incident loss. Open-drive
centrifugal units are not as prone to leakage as the reciprocating units
because they have an oil reservoir at the seal to keep it lubricated dur-
ing periods of nonuse. This oil reservoir is not present on reciprocat-
ing units.
Shaft seals are manufactured from either carbon or ceramic. Carbon
seals are .generally used on low pressure units but have been used to
some extent on high pressure systems. Open-drive centrifugal units pri-
marily use carbon seals. Ceramic seals are used basically only on high
pressure reciprocating compressors.
The principal problems with shaft seals arise during periods of
nonuse, i.e., during the winter months. During this period of time,
the oil necessary to lubricate the seal drains away from the shaft and
the seal is allowed to dry. As a result, the seals will have a tendency
to stick or "freeze" on the shaft so that when the machine is started,
the shaft will tear away from- the seal and create small imperfections
in the seal surface through which the refrigerant can leak. Generally,
if the seal -does not have any major damage, it will reseat and stop
leaking after the unit has been running for about 2 to 3 hr. Another
source of seal leakage occurs if small particles of dirt, metal, etc.,
work their way between the shaft and the seal. When this happens, the
surface of the seal becomes "scored" and continual leakage of the re-
frigerant will occur. A third cause of seal leakage and compressor
failure is due to "slugging" of the compressor by relatively large quan-
tities of liquid refrigerant (or oil) entering the cylinders during
machine start-up. Overcharging with refrigerant can also cause "slugging"
to occur. If "slugging" occurs, it leads to extremely high pressures
being developed within the compressor and will cause seal leakage, blown
head gaskets, or valve and cylinder damage
Ill-41
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The actual amount of leakage from the seal is relatively small for
each machine. Many of the units using seals are 100 ton or lower capac-
ity units, with a refrigerant capacity of less than 500 Ib. However, the
vast majority of the chiller systems are in these lower tonnage units
so that, while the quantity leaked from each unit is small, the cumula-
tive effect is quite significant.
Gaskets and 0-ringsH/ - Gaskets are a very common source of leak-
age in chiller systems. The reasons for leakage appear to be two-fold:
the materials of gasket construction, and the manner in which the flanges
are connected. Flat gaskets and 0-rings for bolted joints can be con-
structed from rubber, buna-N, neoprene, asbestos compositions, or other
materials. Rubber and buna-N will readily break down in the refrigerant-
oil atmosphere within the system and show severe leakage. However, these
materials are still used in some equipment. Flat gaskets are generally
produced from an asbestos-type material.^' The most common material for
0-rings is neoprene, which is favored because it is sufficiently soft
that the joint faces do not have to be perfectly flat or smooth. Because
of its softness, the neoprene will flow into the imperfect faces and form
a good seal. However with time, neoprene will deteriorate, harden or
flatten* Due to the continual heating and cooling of the machine, the
neoprene will crack and develop leaks. The normal lifetime for flat gas-
kets and 0-rings is approximately 3 years before severe leaks develop.
This lifetime is also dependent on the size of the unit and how often
it is operated.
• • - - - • - - - »
Large 0-ring gasketed flange joints are normally either bolted or
clamped with a "V" band, which resembles a barrel hoop used to clamp lids
on barrels. The bolted flanges generally provide an acceptable joint with
respect to leakage. However, the "V" band is considered a poor arrange-
ment and will consistently show leakage*^/ Small vibrations in the sys-
tem are one of the causes of "V" band leakage. Even with no unit vibra-
tion, after a period of time the "V" band will stretch and leaks will
develop. Dresser couplings have been used in the past for joints but
have largely been replaced due to their tendency to leak refrigerant.
Some older machines may still be equipped with these couplings.
Miscellaneous minor sourcesZS/ - Some relatively minor sources of
refrigerant leakage which are common to all chiller systems will be
briefly noted or discussed under this heading.
Vibration in chiller units has been a problem area in the past but
the manufacturers have successfully dealt with this problem. Line crack-
ing and breakages do occur occasionally but not to the degree as in past
years.
Ill-42
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Compressor motor terminals are a common source of small leakages of
refrigerants* Solder joints and the use of flare fittings are frequent
sources of refrigerant leakage* These methods are common leak points on
all types of refrigeration and air conditioning equipment.
Service and Repair Operations - The previous subsection discussed sources
of leakage due to equipment failure. In this subsection, refrigerant emis-
sions directly related to the service and repair operations on chiller
systems will be discussed.
Repair operations - Any repair work conducted within the system will
normally require the removal of the refrigerant charge. For certain types
of failures, the refrigerant may become contaminated while in other fail-
ures, no contamination will occur. Two common problems which result in
contaminated refrigerant are the bursting of a frozen water tube, leading
to water contamination^/ and an electric motor "burnout" in hermetic
systems to produce a hydrochloric and hydrofluoric acid contamination
of the refrigerant. Safety controls are present to prevent the freezing
of water tubes. These valves should be checked and recalibrated annually,
but this is apparently very seldom doneJi^./ Other repairs, such as an
overhaul of the compressor or the welding of a cracked refrigerant line,
would require the removal of noncontaminated refrigerant prior to the
repair operations.
Most manufacturers of high pressure (R-12) units of 100 tons or more
build a transfer pump system and receivers into the unit so that most
of the refrigerant can be transferred while repairs are being made. Lower
capacity units do not have a built-in transfer system so that a transfer
pump must be supplied by the service personnel. In certain instances in
small units, it may be possible by the use of valves to isolate quantities
of the refrigerant in sections of the unit not undergoing repair. However,
based on discussions with manufacturers±LtZ§/ and service personnel^./
and despite some claims to the contrary, most of the contaminated refrig-
erant (either water or acid) appears to be either purged to the atmosphere
or dumped into a sewer drain. This is true regardless of the size of the
unit. For noncontaminated refrigerant in a unit equipped with a transfer
system, that quantity which can be conveniently and rapidly transferred
will be saved and the remainder discarded to the environment. Anonymous
sources in the air conditioning repair sector state that for small capac-
ity units with no transfer system, the vast majority of even noncontami-
nated refrigerant is discarded, either to the atmosphere or to a sewer
drain. Refrigerant disposal practices may also depend on other considera-
tions, such as who will pay for the replacement refrigerant.
The rationale for the lack of recovery of used refrigerant is pri-
marily one of economics. Because of the low wholesale cost of the common
refrigerants, service personnel will recover only that quantity which
III-43
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can be isolated rapidly and conveniently* Economically, it is not fea-
sible to spend time recovering a cheap component. Another quoted con-
sideration concerns the containers to hold the refrigerant.^/ Most re-
frigerant is shipped in disposable drums which cannot, by law, be refilled.
Each service unit would have to purchase new, refillable drums to hold
the used refrigerant during repair operations. Cross-contamination of
refrigerants could be possible unless the drums were cleaned after each
usage or separate drums used for each type of refrigerant.
Service operationsftS/ - Service operations generally are not respon-
sible for the creation of refrigerant emissions, but are partially re-
sponsible for the perpetuation of existing emissions, primarily in the
area of small leakages. It is not rare for a unit, low on refrigerant,
to be refilled but not checked for leaks to determine how the refriger-
ant is being lost. It has been stated that perhaps too many repair orga-
nizations are becoming "refrigerant sellers" rather than attempting to
detect and repair leakages, particularly the smaller ones.^./ Certainly
a portion of this failure to repair leakages can be attributed to the
customer, who would prefer to pay for the added refrigerant rather than
shut down the unit to repair the source of leakage. For a single unit,
the quantity lost may be small but the total number of such units is
large.
Potential Methods of Emission Control - In this discussion, an attempt
will be made to present some possible changes in both equipment and
procedures which would lead to a reduction in refrigerant emissions.
This discussion will consider both the equipment failures leading di-
rectly to refrigerant emission and service and repair operations.
General considerations - Essentially all chiller manufacturers recom-
mend an annual oil change, filter change, equipment test, and leak
.test, f**"8^ The term, equipment test, is used to designate items such
as floats, valves, switches, etc., that can be checked and tested to as-
sure proper operation. Certain items, such as rupture disc pressure re-
lief valves, obviously cannot be tested without rendering that piece of
equipment inoperative. Service companies also recommend an annual leak
test on all chiller systems«z2/ While these procedures are recommended,
they are seldom actually performed or often performed in a very cursory
manner. The performance of leak testing and the repair of faulty equipment
could diminish refrigerant emissions to a considerable but unknown ex-
tent.
An indirect method which is concerned with the overall system might
be the addition of a leak detection system with an audio and/or visual
alarm device. While an alarm system of this nature would not prevent leak-
age, it would alert the maintenance personnel and/or service personnel
III-44
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that a leakage problem exists* An internal system that is currently em-
ployed with food and beverage refrigeration systems (p. 111-55) may be
adaptable to chiller systems.
For smaller leakages, in high pressure units, due to seals, gaskets,
etc., multiple external gaseous refrigerant detectors could be installed
at common leakage points. These detector systems, based on thermal con-
ductivity or infrared detection methods, could be incorporated into a
visual and/or audio alarm system. The cost of the detector systems range
from less than $100 to approximately $2,000rii' depending upon the degree
of sophistication desired.
E. I. du Font de Nemours has developed a system of refrigerant (R-
12 or R-22) plus a red colorant (Dytel®) that would appear to be very
effective in pinpointing many leakages from high pressure chiller unitsJli/
For sources such as flat gaskets, 0-rings, and valves, a visual inspection
would determine the presence of leaks and provide some indication of the
severity of the leak.
Equipment failures - Manufacturers and service companies agree that,
in general, preventative methods for these types of leakages encompass
new equipment, better applications of existing equipment, and better oper-
ating practices. In the following -discussion, methods for emission con-
trol will be delineated for each of the common sources of leakage. For
modifications of existing designs or complete redesigns on new equipment,
the cost of these modifications will be borne by the customer in terms
of increased purchase prices.
Shaft seals-S/ - The new, smaller tonnage chiller units are hermeti-
cally sealed systems which, of course, do not require the use of shaft
seals. Of the new reciprocating chiller units that do require seals, the
majority of these units use R-22; for those units employing R-12, the
problems with seal lubrication appear to be considerably less than those
found with the older machines. Therefore, the basic consideration is for
the replacement of seals in existing units rather than new units.
The design of compressor seals is a complex field and, if satisfac-
tory seal performance and reliability are to be attained, proper mech-
anical seal selection is critical. The two most common seal arrangements
are single inside-mounted seals and double seals; single seals are used
in chiller systems. Properly lubricated double seals provide good seal
reliability and maximum protection against refrigerant leakage to the
atmosphere or the entry of air and moisture into the compressor.^/ How-
ever, for current chiller systems, a complete redesign of the compressor
seal housing and, possibly, a lengthening of the compressor crankshaft
would be required to accomodate a double seal arrangement ,z2/
III-45
-------
The most feasible solution to the problem of seal leakage does not
appear to be a new seal, either in design or material, but rather better
operating procedures. If units employing a shaft seal were to be operated
for a brief period of time each month during periods of nonuse, as recom-
mended by manufacturers and service companies, this procedure would alle-
viate the seal seizure problem and considerably reduce leakage during ma-
chine start-up. During the winter months, some chiller owners pump the
refrigerant into receivers and shut the valves so that the refrigerant
is not in the system. This procedure will eliminate leakage of refriger-
ant through gaskets, joints, etc., but it also will prevent the system
from being started periodically to keep the seals lubricated Jt2.'
Leakage resulting from a "scoring" of the surface of the seal by
dirt, metal particles, etc., can be detected by a leak test and the seal
replaced.
Over pressurization of the seal by "slugging" may be reduced or elim
inated by (1) circulating the refrigerant (or oil) into the motor prior
to entering the compressor cylinder, (2) placing a suction accumulator
(ballast tank) in the refrigerant line, or (3) combine 1 and 2. New semi-
hermetic compressors are designed to circulate the refrigerant into the
motor. A suction accumulator can be installed for approximately
In many instances, there is no valid reason why hermetic compres-
sors could not be used in new systems with the complete elimination of
shaft
Purge systems - For low pressure centrifugal units, this system prob-
ably accounts for more loss of refrigerant on an annual basis than any
other single source. Since the sole function of the purge system is to
remove air from low pressure chiller units, the elimination of sources
of air leakage into the system would re'sult in less air intake and, hence,
a reduction in the use of the purge system. In actuality, low pressure
systems (R-ll and R-113) could be replaced with high pressure (R-12) sys-
tems, if manufacturers were given sufficient lead time to produce small
R-12 compressors. One company (Westinghouse) already produces small R-12
centrifugal compressors. A high pressure system would completely eliminate
the need for purge systems and simplify the leak checking procedure to a
considerable extent. The R-12 systems can use a hermetic compressor sys-
tem, which could result in a tighter system and considerably reduce other
leakages. The additional cost of such a system would result from redesign
and retooling. These costs would, of course, be passed on to the consumer .
III-46
-------
The same purge system is normally used for all sizes (tonnages)
of chiller unitsjt^/ For smaller tonnage units, the purge system can
accommodate larger air leakages and the chiller will remain in opera-
tion; however, the larger air leaks also means that greater quantities
of refrigerant are being lost to the atmosphere. If purge systems were
to be scaled to the tonnage of the unit, a decrease in the quantity
of air that could be accommodated in lower tonnage units would result.
For a 250-ton low-pressure centrifugal chiller, the present cost is
about $31,000 to $32,000. The factory cost of the complete purge sys-
tem is approximately $500 to $1,000 with the bulk of the cost in the
compressor and copper tubing.ft§/ This same purge system is also in-
stalled on small units, e.g., 75 ton units. While the exact material
cost reduction in scaling the purge system to the unit size is un-
known and may not be large, some cost reduction should be possible.
For those purge systems employing a compressor with carbon rings,
the use of a piston type compressor with standard rings and seals would
considerably reduce the backside leakage.46/
A more efficient purge system could easily be designed; it is sim-
ply a matter of economics. By combining higher pressures with lower
purge condensing temperatures, the ratio of the quantity of refrigerant
to the quantity of air emitted from the purge system can be reduced to
almost any desired level. However, as the pressures increase and the
temperatures decrease, the cost of the purge system increases. As an
example, if an extra compressor and a low temperature (R-22) condens-
ing unit were added, a refrigerant to air ratio in the expelled gas of
1:1, as opposed to the current 3 to 5:1, could easily be attained. The
cost of such a system would probably be approximately three times the
current cost of a purge system«J£/
For existing purge systems, an auxiliary low temperature condensing
unit could be installed in the vent system to remove a portion of the
refrigerant from the air prior to release into the atmosphere. Based
on current refrigerant levels in the expelled air, a significant re-
covery of refrigerant may be obtained, depending upon the temperature
of the auxiliary condensing unit. It is estimated that a condensing unit
would cost less than $500, not including installation..^/
Flanges and gaskets - As discussed previously, flanges and gaskets
are common sources of small leakages of refrigerant primarily because
of the temperature variations in the system. The flanged joints on ser-
vice and control valves have been of about the same design for approxi-
mately 40 years. Host of the valves are adapted ammonia valves with seal
caps instead of hand knobs. Seal caps simply retain the leakage instead
of allowing it to discharge directly into the atmosphere; however, when
III-47
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the seal cap is removed to turn the valve, the gas escapes to the atmo-
sphere. The flanges used on these valves either need to be considerably
improved or completely eliminated^!!/ One possibility lies with imported
European flangeless valves. If done properly, e.g., metal to metal welded
joints with an interior 0-ring, a very tight joint can be obtained. The
cost of flangeless valves are comparable to valves made in the UoS
-------
According to this source, reliable mechanical pressure relief devices
are available if time is taken to look for them. It would seem appro-
priate to pressure test mechanical relief devices immediately prior to
their installation to determine if the valve will reseat properly and
not leak* Valves that do not meet specifications could be returned to
the manufacturer.
One possibility for both rupture disc and mechanical devices would
be the installation of an appropriately sized pressure-rated vessel in
the vent system to collect refrigerant lost due to leakage or release
of the relief device. This pressure vessel could be vented to the atmo-
sphere with a pressure relief device in its vent pipe. A pressure gauge
should be added to the tank to indicate the internal pressure. This tank
could be of an appropriate size so that, under ambient temperatures,
it could hold the entire refrigerant charge without venting through its
pressure relief valve but in an emergency, e.g., a fire, the charge
will be vented to the atmosphere to provide firefighter safety. This
auxiliary system would: (1) prevent direct leakage to the atmosphere;
(2) provide a means for refrigerant recovery in the event of a premature
discharge from the relief valve or a mechanical failure in the chiller
•system (e.g., loss of cooling water, etc.); and (3) still provide safety
in case of an emergency such as fire. However, it is possible that a
system such as this may be in conflict with local building codes to al-
low its installation* The cost of an appropriately size pressure-rated
vessel would be dependent upon the refrigerant charge of each chiller
unit.
»
Miscellaneous sources - For the piping system around compressors,
brazed joints, instead of soldered joints,, could be used to provide a
tight system»££.' Compressor motor terminals are a source of small leak-
age. Hermetic type terminals that are threaded could be used instead
of the gasketed type. However, the advantage may be very small because
the terminals are a source of small leakage.^/
Refrigerant recovery - Refrigerant recovery systems applicable to
chiller systems are available from various equipment manufacturers^/
and at least one refrigerant producer.24/ xhese systems have been dis-
cussed earlier in this section. Since large-scale chiller systems (>
100 tons) normally are equipped with built-in pumps and receivers, the
primary systems requiring external transfer and 'storage equipment are
those units of less than 100 tons or contain less than 500 Ib of refrig-
erant.
For the other types of refrigeration and air conditioning discussed
in this section, the basic consideration is economics because of the
relatively small quantity of refrigerant per unit and the low cost of
111-49
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the refrigerant* Economics certainly are also a factor with respect to
chiller systems* For units up to 20 tons, the refrigerant capacity is
less than 50 Ib so that unless the transfer, storage, and refilling can
be conducted rapidly, the collection of refrigerant, based solely on
economic factors, is probably not feasible. If the refrigerant is con-
taminated, either "wet" or "acid", a purification process must also be
included*
With larger chiller systems (e.g., 60-ton units containing 150 to
200 Ib of refrigerant), the decision whether to collect the refrigerant
or not may be a matter of convenience as well as pure economics. For
noncontaminated refrigerant, the release of this material to the atmo-
sphere appears to be almost solely a matter of convenience, although
there certainly is an economic factor to be considered. In the case of
contaminated refrigerant, the purification process must be considered
so that, in terms of pure economics, the ultimate "cost" of recycling
would be dependent upon the quantity of refrigerant and the degree of
contamination. E. I. du Pont de Nemours, for example, will purchase cer-
tain contaminated refrigerants for recycling. Systems are also available
for the repair organizations to do their own recycling. In the final
analysis, it appears that the decision to recovery refrigerants is a
combination of economics and incentive.
Possible options - The following brief discussion of some possible
options is presented here because it seems to be more appropriate to
chiller systems, because of their large capacities, than to the other
types of refrigeration and air conditioning. The enactment of regula-
tions, either with or without capacity exemptions, is an obvious pos-
sibility. Within the scope of regulations, the potential effectiveness
of the enforcement must also be considered both in terms of possible
fines for noncompliance and the degree or scope of the enforcement activi-
ties. Enforcement possibilities could exist at the regional EPA level.
Aside from the regulatory possibilities, the concept of economic
incentives for recovery and reuse could also be considered. Possible
incentives could be in the form of direct grants for recycling services,
subsidies for recycling, potential tax write-offs, and governmental pro-
curement (ETIP). In the area of potential tax write-offs, consideration
may be given not only for the reuse of refrigerant, but also to the pos-
sible conversion of existing chiller systems, which often necessitates
equipment changes, to a "safer" chlorofluorocarbon refrigerant (e.g.,
R-22).
A third possible set of options may be a mixed strategy in which
it may be possible to combine a regulation with various incentives
timed in such a manner as to counter the exemptions. This possibility
111-50
-------
might be conceived in a way so that as the recovery technology improves
and it becomes more economically feasible to recovery refrigerant, the
capacities of systems which would be exempt would likewise decrease.
It should be stressed that the above brief discussion represents
a few possible options that might be considered if some form of action
were to be considered regarding deliberate emission of specific chloro-
fluorocarbons into the atmosphere. The option stated above should not,
in any way, be construed as conclusions or recommendations by MRI with
regard to this problem. Detailed studies of the legal, economic, politi-
cal, and societal ramifications of this subject area are beyond the scope
of this report.
COMMERCIAL FOOD AND BEVERAGE REFRIGERATION
In contrast to home refrigeration, much less marketing information
is available for the commercial food and beverage refrigeration sector.
Direct.contact with associations such as National Commercial Refrigera-
tion Sales Association and Commercial Refrigerator Manufacturers Associa-
tion failed to produce industry-wide marketing data, e.g., annual sales,
number and kinds of units sold, replacement sales, market saturation,
growth trends, etc. Such information is deemed confidential by associa-
tion members.*
The commercial refrigeration equipment field is dominated by Hussmann
Refrigerator Company, St. Louis, Missouri, a division of Pet Incorporated,
which has captured approximately 35% of the market.J>ft/ By contrast, sev-
eral companies, including C. Schmidt Company of Cincinnati, Ohio, and
Golden Cabinet Company of Carlstadt, New Jersey, have an estimated com-
bined 5% market share. The remaining 60% of the market is divided among
the four companies:
Hill Refrigeration Company, Division of Emhard Corporation, Trenton,
New Jersey;
Warren-Sherer Company, Division of Kysor Industries Corporation,
Marshall, Michigan;
Tyler Refrigeration Corporation, Niles, Michigan; and
Friedrich Air Conditioning Refrigeration Company, Division of Weil-
McLain, Inc., San Antonio, Texas.
No individual sales data are available at this time.
The marketing and technical information reported in this portion of
Section III was supplemented by data from the Hussmann Refrigerator
Company.
Ill-51
-------
Most types of commercial refrigerators are shipped from the factory
with evaporator coils but without compressors, condensing units, or re-
frigeration equipment. Remote condensing units or refrigeration systems
are installed on location with appropriate refrigeration components sup-
plied by the manufacturer or a contractor.
Manufacturers of commercial refrigeration equipment do not generally
manufacture the entire refrigeration condensing unit, but rather rely
heavily on components supplied by other manufacturers. Thus, the manu-
facturer purchases the motor-compressor, condensers, receivers,'tubing,
valves and other fittings, electrical components, and numerous small hard-
ware based on the design and specification. The manufacturer does design
and manufacture the steel control panel enclosure for the condensing unit.
Much emphasis is placed on engineering design to reduce overall
energy consumption by balancing store cooling, heating, and dehumidifica-
tion requirements, along with refrigerator cooling and defrosting, in re-
tail stores. The manufacturer designs and assembles the food and beverage
display cases, coolers and freezers which generally are connected by
piping to refrigeration units in a separate location in the store. The
energy requirements of the equipment are affected by temperature and
humidity in the store. For this reason, proper design of the air con-
ditioning and heating system to provide optimum conditions in the store
is important. Some refrigerator manufacturers provide this equipment.
Estimated Refrigerant in Use and Annual Losses
According to one source 80 + 5% of all commercial refrigerant pres-
ently in use for food and beverage storage and display cases is R-12.2-L'
New and remodeled installations are using R-502 for low temperature ap-
plications, e.g. , frozen food and ice cream storage and display, and R-
22, R-12, and R-502 (small quantities) for medium temperature applica-
tion, e.g., meat, produce, dairy, and delicatessen. For example, R-502
has been used exclusively in low temperature application for at least
the last 15 years, with R-12 only being used for refrigerators display-
ing those products above freezing. In the near term time interval, e.g.,
to 1985 to 1990, emissions from commercial refrigeration within the pres-
ent scope of inquiry will primarily consist of R-12; but by the year 2000,
if present trends prevail, emissions will be essentially R-502 and R-22.
The total amount of R-12 refrigerant in the commercial food and
beverage storage and display sector in 1973 has been estimated..!/ From
the published data, the total refrigerant, as R-12, in service for this
sector in 1973 is estimated to be near 150" million pounds. The annual
R-12 emissions are estimated to be near 28.2 million pounds.
Ill-52
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By contrast, one industrial source estimates the total amount of
R-12 refrigerant in all classes of grocery stores is near 73 million
pounds.54/ Table III-5 utilizes data from a grocery trade magazine.^/
Table III-5. ESTIMATED QUANTITY OF R-12 IN GROCERY STORES (1975)
Business
volume ($)
1,000,000 +
Store
classification
Super markets
(including chain
and independent
operations)
Superettes
Small stores
(including chain,
small stores, and
'independent small
stores)
Convenience stores < 500,000
Total
500,000 to
1,000,000
< 500,000
Number
of
storesj-L/
31,710
12,800
122,300
1,200
600
200
100
38,052,000
7,680,000
24,460,000
191,810
2.500.000
72,692,000
If the estimate of 73 million pounds of R-12 currently is used is
reasonably correct, the annual emissions of R-12 may be more nearly 14
million pounds, instead of 28 million pounds.
Sources of Chlorofluorocarbon Emissions
Present state-of-the-art commercial food and beverage refrigeration
units consist of three basic approaches. The first being a bank of four
semihermetically sealed motor-compressor units (5% of total installations)
connected in parallel to a manifold of isolation and regulating valves
which serve evaporators and condensers. The latter components serve either
normal temperature coolers or display refrigerators for fresh foods (R-22)
or low temperature frozen food lockers or display refrigerators (R-502).
111-53
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Refrigerators are connected to the compressor banks by tubing on the job-
site. The parallel arrangement is an energy saving feature because.one
or more compressors can cycle on and off as the demand varies* This sys-
tem generally does not employ the use of R-12. The discussion is pre-
sented to indicate the present state of the art in this area* It may be
possible for R-12 to be used in this system, but its usage would very
likely result in lower operating efficiencies and a possible increase
in energy consumption*
The second approach involves two compressors mounted in parallel
instead of four, but with other factors being essentially the same.
These installations represent about 10% of the total installations.
The third and by far the largest installation practice is the in-
stallation of a single condensing unit connected in parallel to one or
more refrigerators for identical utilization, for example, five or six
refrigerators serving produce refrigeration and display. These installa-
tions represent about 85% of the total installations^./
Extensive use is made of heavy walled copper tubing with brazed
joints using silver solder* Special aluminum-copper transition solder
joints are provided by the refrigerator manufacturer for joining alumi-
num evaporators to copper tubing when aluminum is used.
The compressors are generally fractional horsepower through 25 h.p.
semihenaetic units which are sealed units in the sense that the motor
and compressor are sealed in a common housing in which the refrigerant
circulates freely. There are one, two, or three bolted, gasketed.cylinder
heads for removal and replacement of valve plates in each bank of cylinders*
These portions of the motor compressor are potential leakage points*
There are suction and liquid lines running to the refrigerators and
also discharge and return lines to and from the condensers which in some
instances are roof mounted* If the joints have been properly brazed,
there is little chance for leakage. The suction lines in some stores are
insulated to prevent condensation and building damage and does provide
some protection to the tubing*
Vibration in the entire assembly of components is kept to a minimum
by proper physical supports and engineering design. Vibration eliminators
are mounted in the piping on some installations.
A multi-valved manifold panel permits each line to a food storage
cooler, or display refrigerator to be regulated, isolated, or tested for
leaks* Each line has an individual capped service port* These components
are all potential leak points* There may be as many as 100 potential leak-
age points in the manifold system serving a large supermarket*
111-54
-------
Sophisticated systems such as these have at least three methods for
detection of refrigerant leakage or malfunction: .
1. An automatic bell alarm which warns employees in the store of
malfunction of the system and rising temperatures in freezers and coolers,
This alarm/warning; system is actuated by a floating lever arm mechanism
in the" liquid"refrigerant receiver. When the float on the liquid refrig-
erant falls below a predetermined level in the receiver, the lever-arm
attached to the float trips a relay switch sounding the bell alarm and
automatically contacts the service organization and/or the grocery chain
maintenance engineer at the central office*
2* :Same as the above but the alarm only goes off in the store*
3* These automatic warning systems are backed up by routine check-
ing by employees of the supermarket who are required to visually check
thermometers located within each cooler, refrigerator* freezer, or dis-
play case*
The last backup technique to the automatic alarm systems is not
dependable according to a maintenance engineer who is employed by a
Kansas City-based grocery chain* Grocery clerks, meat cutters, and
helpers simply cannot be depended upon to monitor the cases daily*
Figure III-8 presents a schematic diagram of the current state-of-
the-art multiplexing arrangement for supermarkets* Several compressors
are combined in parallel to serve various parallel arrangements of
coolers, freezers, beverage cases, and other display refrigerators.
The figure indicates a common condenser, usually roof-mounted* Other
portions of the refrigeration system are self-explanatory or indicated
in the figure*
A very few large supermarkets not of recent vintage have refrigera-
tion systems, employing R-22, that are termed "compounded" in which the
store has one or more medium temperature compressors and one or more low
temperature compressors connected in series with the medium temperature
compressors* The medium temperature compressor has a suction line not
only from the low temperature compressor, but also from the medium tem-
perature refrigerators* The suction line to the low temperature com-
pressor comes from the low temperature refrigerators* Both types of com-
pressors run constantly* However, they are designed for "compressor un-
loading," i.e., as the load requirements decrease for the refrigerators,
one or more of the compressor cylinders become "unloaded" and do not
pump refrigerant; the piston simply moves freely in the casting*
111-55
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3
/ ^
1C
)
f -S
<(
3
(-*
„;,. ,...
.
.
Isolation Valvesj
2
v
o>
Liquid Refrigerant
FTT1-
M
£
Fans
Condenser Unit
Mounted on Roof
Motor-Compressor Units
Suction Manifold
Receiver
Liquid Manifold
Solenoid Valves
Expansion Valves
Cooler, Meat, Produce,
and Display Cases
Temperature Control Valves
Suction Line
Figure III-8. Schematic of current state-of-the-art commercial
food and beverage refrigeration systems
III-56
-------
Direct drive compressors are used which utilize a shaft seal*
Leaks may be a minor problem if the system was originally properly in-
stalled, e.g., nearly vibration free, brazed joints, etc. However, the
previous comments regarding potential refrigerant emission sources are
equally valid for these systems*
Older and modern day R-12 refrigeration systems for supermarkets
and small grocery and liquor (package) stores rely on a number of in-
dividual condensing units serving several similar display cases or
coolers at the same temperature level* Even though only one condensing
unit is attached to the food and beverage refrigerators, the compressor
does cycle on and off based on the specific requirements of the refrig-
erators*
Figure III-9 presents a schematic of a very old R-12 type of con-
ventional refrigeration assembly. In this particular arrangement a
belted, open compressor is ..driven by an electric motor* The compressor
serves three coolers or display cases hooked together in a parallel
arrangement with the single compressor* This type of belt driven com-
pressor is at least 20 to 25 years old.
Sources of refrigerant leaks in very old systems include the com-
pressor crankshaft seals, the cylinder head gasket, various isolation
and purge valves, any vibration sensitive joints and seals (typical
older refrigeration systems were often poorly designed and installed
with little thought to eliminate vibration), various isolation valves
and purge ports, etc*
A visit to a local package store built 30 years ago revealed a
complex arrangement that had grown over the years with little or no
redesigning of the total refrigeration systems* Four 1*5 h.p*, belted,
open-compressors served five food and beverage display cases, a large
walk-in cooler, and an ice cream display case* The compressors ran
continually and the refrigeration system was obviously taxed to its
limit. All four compressors exhibited excessive vibration, because of
improper installation or inadequate motor mounts. A flexible metal hose
was attached to one compressor which was vibrating much worse than the
others. All metal piping exhibited some vibration from each of the other
compressors. Often the vibration was noticeable for several feet from
the compressors*
Uninsulated copper piping was used throughout the system* Joints
and fittings were soldered (presumably silver solder was used) and
several joints had been soldered many times as evidenced by large amounts
III-57
-------
M
I
Ul
00
nnnnnn
FLOORING OR PANELING
HIGH PRESSURE
LIQUID LINE
T
nnrnnnnn
CONTROL AND
ISOLATION (RISER)
VALVE PANEL
LOW PRESSURE
SUCTION LINE
DRIER-STRAINER
AUTOMATIC WATER
REGULATING VALVE
COOLING
WATER INLET-
innnr
BASEMENT OR
INTERIOR ROOM
COOLING WATER
OUTLET
C - COMPRESSOR
M = MOTOR
R = REFRIGERANT RECEIVER
Figure III-9. Typical old commercial food and beverage refrigeration system
-------
of solder splashed on the piping which was heavily oxidized by exces-
sive heat. Servicing of the units was accomplished through extensive use
of capped valves. Many fittings and couplings were observed as potential
leak points. The proprietor did not routinely check thermometer readings,
but merely spot-checked unit performance on an irregular basis. There was
no regular maintenance service call, but rather, the proprietor contacted
a local maintenance company when a problem occurred.
These examples represent the extremes in current food and beverage
storage and display refrigeration systems. On the one hand, systems of
excellent engineering design and installation and under constant mainte-
nance and inspection are found in the field. Conversely, many small add-on
systems, improperly designed, installed and maintained also exist. Un-
fortunately, all systems can lose refrigerant through many similar po-
tential points. The principal cause of leaks is a result of vibration in
the following areas:
Brazed joints Fitting fatigue
Compression fittings and plates Elbow fracture
Isolation and purge valves Capillary tube rupture
Seals in belted, open compres-
sors in older systems
Particularly vulnerable are the service valves. Graphite packing
often fails to hold refrigerant. In addition, poor and inadequate oper-
ating and maintenance procedures can contribute to refrigerant release
to the atmosphere; e.g., unnecessary purging of refrigerant during ser-
vicing with no attempt to transfer and contain the original charge. Of
course, leakage of refrigerant can occur in the condenser and evaporator
units as well as through metal rupture, corrosion, improperly brazed
joints, etc.
Service and Maintenance Practice
Large refrigeration systems in supermarkets can contain between
600 and 1,200 Ib of refrigerant. An Arthur D. Little report on halocar-
bonds estimated an average of approximately 675 Ib of refrigerant per
store, about 80% of which is currently R-12.1!5^ The cost of refrig-
erant to the store owner is close to $1,300 when purchased in 50-lb
drums, which is usually carried by a serviceman.
111-59
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Failure in a supermarket refrigeration system does not necessarily
require purging most of the system to isolate and repair a leakage point.
A well engineered system will have many isolation valves. These features
help in locating the leak and in minimizing losses during repair while
permitting use of other parts of the total refrigeration system. Thus,
when the refrigeration repairman checks the system, he invariably locates
and isolates the problem area using a leak detector, thereby defining a
very limited quantity of refrigerant for replacement. This may be much
less than 100 Ib if the problem is minor. The dollar loss of refrigerant
may be of the order of $100, which is far less than the potential cost
of spoiled or degraded food products.
Such is the current practice for small leaks or minor problems in
commercial refrigeration systems. The service repairman locates and iso-
lates the trouble point, e.g., a ruptured line, a leaky seal or fittings,
etc. That section of the system is pumped down, thus causing the refrig-
erant to migrate to the receiver tank so that the rest of the system can
be opened. The serviceman repairs or replaces the faulty component, evac-
uates the system several times to remove moisture and air, tests for leak-
age, charges the system with the proper amount of refrigerant, and tests
for leakage again. If no leakage occurs, the appropriate valves are opened
to allow the system to operate normally.
If a compressor fails or burns out due to "slugging" with liquid
refrigerant or overloading, then the refrigerant in a large portion*of
the system may be contaminated with metal particles, decomposed motor
winding insulation, oil, water, dirt, dust, etc. In this case, the ser-
viceman may use filter-driers to remove contaminants from the refrigerant
after replacing the compressor. Alternately, the serviceman may replace
that portion of decomposed refrigerant with fresh refrigerant if, in his
opinion, there is an undue risk to the system in using the original re-
frigerant even though it might have been passed through filter-driers.
Both practices are found in the field.
In some instances purging of small amounts, e.g., 10 Ib, of refrig-
erant to the atmosphere is common practice if the quantity of refrigerant
in the system is small and the clean-up process is not economical.
Methodologies to Reduce and/or Eliminate Emissions
Hardware Improvement - Refrigerant loss occurs through leaks in components
including accidental line rupture, fittings, valves, elbows, faulty com-
pressors, faulty refrigerant control units, etc. The total refrigeration
system is only as good as the components themselves and the manner in
which they were engineered, installed, and serviced.
111-60
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Generally speaking, older commercial refrigeration systems now in
existence which have grown over time by the addition of more compressors
and food and beverage refrigerators are the most troublesome to maintain
properly and are the biggest source of refrigerant losses in the food
store and beverage sector. Ideally, these systems should be retired and
replaced with modern, efficient, properly engineered components includ-
ing new display refrigerators to take advantage of current energy effici-
ent systems* Remodeling or completely converting to a modern system would
do much to reduce refrigerant losses since the older, belted, open-
compressors would be retired*
The cost of modernization of refrigeration system would have to be
borne by the owner-operator and would be substantial, perhaps amounting
from $9,000 to $12,000 for a small grocery or package store and $250,000
for a large supermarket,^/ These costs would eventually be passed on to
the consumer in the form of higher prices* The economic impact of such
an updating has not been fully evaluated; however, a rough approximation
of the costs accruing from this suggestion is given in Table III-6. This
table presents a major commercial refrigeration company's detailed break-
down of estimated costs to replace existing large supermarket and small
grocery store refrigeration systems*^/ The total amount for complete re-
placement of existing, older refrigeration systems, including display
refrigerators, coolers, and storage cases, compressors, condensers, evap-
orators, labor, and materials ranges from $9,000 to $12,000 per store
for small grocery stores (family owned; package stores; or small chain*
stores) to $222,000 to $279,000 per supermarket for large chain stores*lft/
Several points must be made to fully understand the development be-
hind Table III-6 for each type of grocery store operation* The small
grocery stores do not have extensive, sophisticated refrigeration systems
primarily because of individual preference, capital investment, operating
cost, and/or cash flow limitations* These store owners would prefer to
rely on modern hermetic, self-contained refrigerators similar to those
found in the home* There would be no remote compressors and condensers,
alarm systems, complicated parallel arrangements of units, etc., Con-
sequently, the replacement cost of a new refrigeration system (neglecting
trade-in value of older equipment and depreciation credits) would be pri-
marily limited to the purchase of new self-contained display refrigerators
plus installation charges, including labor, materials, and remodeling
changes. The figure of $9,000 to $12,000 is based on 2,400 sq ft (a typi-
cal convenience style store operation) containing three to four refrigera-
tion cases and no back room coolers or storage.
111-61
-------
Table III-6. TOTAL ESTIMATED REPLACEMENT COST OF REFRIGERATION SYSTEM
IN SUPERMARKETS AND SMALL GROCERY STORES
Refrigerators and storage coolers
Remote condensing units, including
seraihermetlc compressors and re-
mote condensers
a* Single condensing units to
coolers and refrigerators,
or
b. Twins (two compressors in
parallel), or
c. Quads (four compressors in
parallel)
Walk-In coolers
Evaporators and fans
Installation, including labor,
piping, and electrical ser-
vices, controls, and refrig-
erant
Total per store
Small grocery
stored)
6,000-8,000l/
3.000-4.000
9,000-12,000
Average super-
market (t)
40,000-60,000&/
12,000-17,000
13,000-19,000
16,000-23,000
6,000-10,000
2,000-3,800
13.000-22.000
102,000-154,800
T/Small grocery store - 3 to 4 refrigerators per store at f2,000 each.
b/ Average supermarket - 20 to 30 refrigerators per store at $2,000 each.
£/ Large supermarket - 60 to 70 refrigerators per store at $2,000 each.
Large super-
market (t)
120,000-140,000^'
35,000-40,000
/
40,000-45,000
50,000-55,000
20,000-25,000
7,000-9,000
40.000-50.000
222,000-279,000
-------
The large supermarket would probably completely strip the old refrig-
eration system including older display cases and coolers from the store*
The calculations are based on such an event and are for a store contain-
ing 30,000 sq ft with 60 to 70 refrigerators and freezers at $2,000 each.
The figure of $222,000 to 1279,000 per store represents remodeling' costs
to the present state-of-the-art supermarket refrigeration systems, neglect-
ing trade-in value and depreciation credits. On a nationwide basis there
is a total of approximately 31,710 large supermarkets, 12,800 average
supermarkets, and 147,000 smaller grocery stores;^/ however, not all of
these stores would necessitate revision.
Short of a complete modernization of the entire system, where can ,
the existing systems and component hardware be improved? The responsibility
for hardware improvement lies with the component manufacturers, the total
system manufacturers, the distributors, and the installation personnel and
will require cooperation between these four economic units.
For older (over 20 years old) belted open-compressors the seal on
the rotating crankshaft is a potential leakage point. Semihermetic motor-
compressors which have been used for the last 20 years have eliminated
this point source. The very old open-compressor has a single crankshaft
seal because it was cheaper and easier to design and fabricate than a
double-seal system. The latter system, when properly lubricated, offers
greater reliability and maximum protection against refrigerant loss. It
is not possible nor desirable to convert an older compressor from a single
seal to a double seal system. If modernization of a refrigeration system
is desired, then conversion to a semihermetic compressor is preferred. A
discussion of improvements in seals, designs, and materials for large in-
dustrial components is contained elsewhere in the body of the report.
Another cause of compressor failure is due to "slugging" of the com-
pressor by relatively large quantities of liquid refrigerant (or oil)
entering the cylinder during start-up or refrigerant over-charging. This
leads to extremely high pressures being developed within the compressor
and causes seal leakage, blown head gaskets, valve and/or internal damage.
Slugging may be reduced or eliminated by (1) designing the compressor so
that refrigerant and oil circulates into the motor portion prior to enter-
ing the compressor cylinder in a semihermetic system and/or (2) placing
a properly sized suction accumulator in the refrigerant suction line in
series with the motor compressor unit. Older systems can be modified by
adding a suction accumulator in the refrigeration suction line between
the evaporators in the display cases and the motor-compressor. The cost
of a suction accumulator is from $100 to $125 depending on the capacity
required. Suction accumulators are readily available for brazing or weld-
ing into present commercial systems from several companies.££/
111-63
-------
New Operating and/or Maintenance Practices or Procedures - In practice
the maintenance/service repairman must transfer a portion of the refrig-
erant from the large cylinders or drums to smaller service cylinders with-
out loss of refrigerant. Careless transfer of the refrigerant from the
large to the small service cylinders in the field can waste much refrig-
erant. A charging board or station consisting of a glass cylinder or mea-
suring tube to estimate the amount of refrigerant in pounds, an evacuating
pump, and various valves provides an accurate means of transfering refrig-
erant without loss* Charging boards are available in several sizes depend-
ing on the use, e.g., a highly portable unit for small to medium size
systems in the field (as may be found in supermarkets) range from $3,000
to $3,800 and are capable of handling up to 145 Ib of refrigerant. Larger
industrial charging boards for use on production lines (for serving 25 to
100 cooling units per day) range from $6,300 to $12,700.13/
In many cases, e.g., small commercial systems in supermarkets, dis-
posable refrigerant cylinders (cans) are used.56/ These pressurized ser-
vice cans may contain 1 to 10 Ib refrigerant and are operated by a special
piercing valve assembly tiiich is clamped to the top of the can. The cans
are convenient for charging known quantities of refrigerant into commercial
systems without loss when used in conjunction with a charging board.
Present technology for dehydrating refrigeration systems by high
vacuum technique and recharging with a precisely measured quantity of re-
frigerant has been developed to a high degree over the past 35 years.
Field service repairmen can readily take advantage of this technology in
reducing refrigerant handling losses to a minimum.
Ill-64
-------
REFERENCES
!• Arthur D. Little, Inc., "Preliminary Economic Impact Assessment
of Possible Regulatory Action to Control Atmospheric Emissions
of Selected Halocarbons," EPA Contract No. 68-02-1349, Task 8,
Publication No. EPA-450/3-75-073, September 1975, NTIS No. PB-
247-115.
2. Merchandising Week, December 9, 1974, p. 7.
3. Merchandising Week. November 10, 1975, p. 22.
4. Applicance Manufacturer, January 1975, p. 76.
5. Appliance Manufacturer, January 1976, p. 94.
6. MEI estimate based on information from manufacturers and/or re-
pair organizations.
7. U.S. Industrial Outlook - 1975, U.S. Department of Commerce,
p. 321.
8. Chemical Technology and Economics in Environmental Perspectives,
Task I - Technical Alternatives to Selected Chlorofluorocarbon
Uses, Environmental Protection Agency, EPA-560/1076-002,
February 1976.
9. Cutler, W. 6., Whirlpool Corporation, Benton Harbor, Michigan.
10. Marz, L., Amana Corporation, Amana, Iowa.
11. Occupational Outlook Handbook, 1974-1975 Edition, U.S. Department
of Labor, Bulletin 1785, 1974, p. 412.
12. U.S. Department of Commerce, 1972 Census of Business, Vol. 3,
p. 8, December 1974«
III-65 ~
-------
13. Doolin, J., Doolco Inc., Dallas, Texas.
14. Braun, G«, Natkin Service Company, Denver, Colorado.
15. Refrigerant Recovery Unit, Model No. 10003, Lehigh Inc., Easton,
Pennsylvania.
16. Geist, C., Air Conditioning and Heating News, p. 30, March 29,
1976.
17. Dickson, 6., King-Seeley Thermos Company, Albert Lea, Minnesota.
18. Soling, S. P., President, St. Onge, Ruff and Associates, Inc.
19. Third Purdue Compressor Technology Conference, July 6-9, 1976,
West Lafayette, Indiana.
20. Shaffer, R. W., and W. D. Lee, "Energy Consumption in Hermetic
Refrigerator Compressors," Arthur D. Little, Inc., Cambridge,
Massachusetts.
21. Schroeder, 6. H., "Improved Efficiency Compressors for Household
Refrigerators and Freezers," Tecumseh Products Company, Tecumseh,
Michigan.
22. Althouse, A. D., C. H. Turnquist, and A. F. Bracciano, "Modern Re-
frigeration and Air Conditioning," Goodheart-Willcox Company,
Inc., Homewood, Illinois, 1968, Chapter 12.
23. Airserco Manufacturing Company, Pittsburgh, Pennsylvania; Lehigh
Inc., Easton, Pennsylvania.
24. Du Pont Refrigerant Reclaimer, Bulletin RT-58, Refrigerants Group,
E. I. du Pont de Nemours and Company, Wilmington, Delaware.
25. E. I. du Pont de Nemours and Company, Bulletin FD-1, Freon® Products
Division, Wilmington, Delaware.
26. Automotive News, Issues No. 4540 (April 23, 1975) and No. 4572
(December 3, 1975), Marketing Services, Inc.
27. 1975 Automotive Facts and Figures. Motor Vehicles Manufacturers Asso-
ciation, Detroit, Michigan.
28. Brad Hilliard, York Division, Borg-Warner Corporation, York,
Pennsylvania.
111-66
-------
29. Janes £. Holtslag, Chrysler Corporation, Detroit, Michigan.
30. Freon® Technical Bulletin B-12C, £, I. du Pont de Nemours and
Company, Inc., Wilmington, Delaware.
31. Freon® Technical Bulletin B-41a, E. I. du Pont de Nemours and
Company, Inc., Wilmington, Delaware.
32. Freon® Technical Bulletin ET-51, E. I. du Pont de Nemours and
Company, Inc., Wilmington, Delaware.
33. Ross Kelly, American Motors Corporation, Detroit, Michigan.
34. Red Maier, Southwest Factories,. Oklahoma City, Oklahoma.
35. R. Robert Paxton, Pure Carbon Company, St. Mary's, Pennsylvania.
36. Dick Washington, Bummerr Seal Company, Franklin, Illinois.
37. David D. Baker, Ford Motor Company, Dearborn, Michigan.
38. Charlie Earl, Alpha Electric Refrigeration Company, Detroit,
Michigan.
39. Lou Costello, Mid-America Gasoline Dealers Association, Kansas
City, Missouri.
40. Telephone survey of auto salvage yards in the Kansas City area.
41. Site visits to several automotive air conditioning service shops
in the Kansas City area.
42. Packless Metal Hose Company, Mt. Wolf, Pennsylvania.
43. J. V. Weigle, Tecumseh Products Company, Tecumseh, Michigan.
44. MRI engineering personnel.
45. Bubeck Service Agency, Trane Air Conditioning, Lenexa, Kansas.
46. Natkin Service Company, Kansas City, Missouri.
47. H. T. Gilkey, Air-Conditioning and Refrigeration Institute,
Arlington, Virginia.
Ill-67
-------
48. Carrier Machinery and Systems Division, Carrier Refrigeration
and Air Conditioning, Kansas City, Missouri*
49. Abar, J. W., "End Face Seals for Air Conditioning Compressors,"
Purdue Compressor Technology Conference, West Lafayette,
Indiana (1972).
50. Traver, D. A., and C. D. Miller, "Saddle Damage of Cooler Tubes,"
ASHRAE Journal, p. 46, March 1976.
51. Personnel at E. I. du Pont de Nemours, Wilmington, Delaware.
52. Refrigeration Research, Inc., Brighton, Michigan.
53. Soling, S. P., "Refrigeration: Food for Thought." ASHRAE Journal,
p. 60, December 1975.
54. Dickson. E. V., Hussmann Corporation, Bridgeton (St. Louis), Missouri.
55. Progressive Grocer, April 1976, p. 75.
56* Althouse, A* D,, C. H. Tumquist, and A. F. Bracciano, 'Modern
Refrigeration and Air Conditioning," Chapter 15, The Goodheart-
Willcox Company, Inc., Homewood, Illinois (1968).
Ill-68
-------
SECTION IV
FOAM BLOWING AGENTS
CHLOEDFLUOEDCARBON CONSUMPTION IN PLASTIC FOAMS
Chlorofluorocarbons (primarily F-ll and F-12) are employed as blow-
ing agents in the production of plastic foams made from polyurethanes,
polystyrene, and polyolefins. These compovinds are used, either as the
primary blowing agent in styrene and polyethylene foams or as an auxiliary
blowing agent in urethanes, to form the cellular structure of these foams.
Other types of plastic foams (primarily urea, phenolic, vinyl, and epoxy
foams) are produced in much smaller volume, and do not typically involve
the usage of chlorofluorocarbon blowing agents.
The 1975 consumption of Chlorofluorocarbons as blowing agents is
estimated to be 80 to 84 million pounds, roughly 9% of total U.S.1 pro-
duction for 1975. Flexible and rigid urethane foams together account
for more than 90% of-total usage of Chlorofluorocarbons as foam blowing
agents. Rigid urethane foams consume substantially greater.quantities
of these compounds than are used for flexible urethane foams. However,
chlorofluorocarbon emissions from flexible foam are many times greater
than those from rigid foams.
The primary reason for this discrepancy is that blowing agent vapors
are largely retained within the rigid urethane foams, while all of the
blowing agents used for flexible foams diffuse to the atmosphere promptly
after foaming.
Because chlorofluorocarbon consumption for plastic foams is domi-
nated by the two classes of urethanes, major attention will be directed
toward emissions and possible emission control systems for the urethane
foams, with less detailed consideration of styrene and olefin foams.
To ascertain the extent to which it may be feasible to control chloro-
fluorocarbon vapor emissions in foam production, it is necessary to exam-
ine each of the major foam production processes. The practicality of
achieving significant reductions in the quantity of blowing agents dis-
charged to the atmosphere depends largely on how much chlorofluorocarbon
IV-1
-------
vapor is lost from various production stages in different foaming tech-
nologies, and the extent to which these vapors can be collected for pro-
cessing or recovery.
An analysis of chlorofluorocarbon losses has been performed for those
foaming processes accounting for nearly all current production of urethane
foams: '
* Flexible slab foams;
* Flexible molded foam shapes;
* Rigid boardstock and billets;
* Rigid foam core panels;
* Rigid foam and froth cavity filling (in-plant); and
* Rigid foam applied on job-site.
In the sections which follow, the main features of each process which
affect the quantity of chlorofluorocarbons emitted from foams will be
highlighted with emphasis on the practicality of collecting these vapors
for subsequent treatment or recovery. To aid in comparing chlorofluoro-
carbon consumption and emissions, a "model plant" will be defined for
each of the six types of foam processes. These plants are intended to
typify current industrial practice on average size or larger, fairly
modern production lines. Although it is patent that one model cannot re-
flect the wide range of commercial conditions for an entire segment of
the foam industry, we believe the use of these model plants can help to
clarify both technical and economic aspects of chlorofluorocarbon emission
control systems.
FLEXIBLE URETHANE FOAMS
Three times as much flexible urethane foam is produced annually as
rigid foams. Host flexible urethane foam is produced by fairly large
firms utilizing high capacity, continuous production lines.
Approximately 70% of flexible foam is produced by the continuous
slab or bun stock process (see Table IV-1), while the balance is fabri-
cated by molding into specially shaped and cored parts. Substantially
all of carpet underlay, textile and clothing laminating foams, and mat-
tresses and bedding are produced as slab stocks. Furniture seats and
cushions require molded shapes as well as cut sheet foams. Automotive
IV-2
-------
foams span a wide range, typically involving sheeting for door padding,
deep molded seating, and medium density crash padding for dash, sun
visors and head rests. Some of this foam is purchased from major pro-
ducers, but over 50% of automotive foams are captively produced in the
body plants where they are used.
Table IV-1. 1975 FLEXIBLE URETHANE FOAMS, ESTIMATED PRODUCTION
BY FOAMING PROCESS
1975 Consumption (million Ib)
Application % Slab M.P. Slab Mobay Slab
Bedding 90 136.4 122.8 142 127.8
Furniture 80 352.0 281.6 447 357.6
Carpet underlay 100 30.81/ 30.8 93J>/ 93.0
Transportation 50 341.0 170.5 320 160.0
Textile laminates 100 26.4 26.4 21 21.0
(ex. carpet)
Packaging 80 19.8 15.8 10 8.0
Other 70 17.6 12.3 11 7.7
Total 924.0 660.2 1,044 775.1
Balance molded 264.0 268.9
and other
Percentage slab 71.5% 74.2%
and bun
£/ Prime foam only; excludes 60 million Ib prompt scrap and re-
claimed foam - foam shredded and rebended to form controlled
density resilient padding.
jj>/ Does not include "bonded" foam consumption.
Source: Estimates based on References 1 and 2.
An approximate distribution by major foam production process is shown
in Table IV-1. The two recent breakdowns by end-use differ somewhat with
regard to individual applications, but both sources indicate that slab
foam processes account for some 72 to 75% of current U.S. flexible ure-
thane foam production.^2./
IV-3
-------
Each of the major processes for producing different types of flex-
ible urethane foams, i.e., continuous slab stock and molded shapes,
possess characteristics that influence the degree to which chlorofluoro-
carbon emission controls may be technically feasible. These two types
of production lines will be briefly described* For each process these
characteristics will be incorporated into a representative "model plant"
and will be specified as one basis for considering the applicability of
various types of emission control systems.
Flexible Urethane Slab
Production of Flexible Urethane Slab - The manufacture of flexible ure-
thane sheet or slabs is performed on continuous production lines re-
quiring extensive specialized facilities* Typical producers include the
major tire and rubber firms, chemical companies, and large furniture and
mattress companies* Virtually all of these large volume producers make
or purchase the basic ingredients, and create their own formulations to
generate foams employing the "one-shot" mixing process.
Much of the success of urethane foam production is related to the
development of reliable mixing and dispensing equipment, together with
sophisticated material handling systems. A typical flexible foam line
employs high production rates, dispensing reactants at 130 to 1,000 lb/
min, and the complete foam line is often over 200 ft in length. A gen-
eral plan layout for a flexible slab foam plant is shown in Figure IV-
lJ/
Plant facilities which relate to chlorofluorocarbon handling com-
prise:
* Unloading track and dock,
* Transfer pumps, hoses, lines,
* Bulk storage tanks (pressurized),
* Pre-mixing and blending weigh tanks,
* Recirculating or stirred dispensing tanks,
* Dispensing unit and control system,
* Primary foaming conveyor and tunnel,
IV-4
-------
-A,!
B
•-
-------
* Secondary bun conveyor to cut off and trim saws,
* Take-off conveyor to storage area, and
* Storage and aging racks.
In commercial continuous-slab production by the one-shot process,
the reactants are pumped by accurate metering pumps (+ 0*5%) from the
storage tanks, through heat exchangers, to the mixing head* Host sys-
tems employ three-way valving at the head, which allows material streams
to recirculate back to the storage tanks or be diverted into the mixing
chamber of the dispensing head. Storage tanks are usually pressurized
with dryinitrogen so that chlorofluorocarbon vapors do not escape and
moist air is not allowed to enter the tanks.
the mixing head allows each chemical stream to recirculate, or
enter the mixing chamber at exactly the same instant. Complete mixing
within the dispensing head can be achieved by (1) high-speed rotating
mixers, (2) static or helical mixers, or (3) high-pressure stream im-
pingement mixing.
In the most widely employed bun process, the mixed reactants flow
from the mixing head and pour onto a continuously moving belt or web of
release paper, so that a foam loaf is formed as the reaction takes place.
This bun loaf is usually 6 to 8 ft wide and rises 2-1/2 to 4 ft high,
depending on foam density and throughput. Wide, high-rise buns maximize
the amount of-.prime, uniform foam, with the least amount of side and top
skin trim.
Two basic methods are employed to generate the foam loaf. Most com-
monly, the mixing head is mounted on a traversing bridge which moves the
head (or heads) back and forth at right angles to the foam conveyor so
that overlapping parallel lines of liquid are laid down. The primary foam-
ing conveyors range from 50 to 100 ft in length and travel at speeds from
12 to 20 ft/min. Near the dispensing point, the conveyor line slopes down-
ward some 5 to 10 degrees to prevent the liquid mix from falling into the
rising foam. Typically, the foam is dispensed onto a paper sheet which
moves along with the conveyor. The conventional traversing foam system
is illustrated in Figure IV-2a.i/
More recently, fixed dispensing heads have been arranged to deliver
reactants to the bottom of a V-shaped trough where the foam rises to the
top before contacting the sheet of release paper. Since the reactants
are delivered beneath a blanket of expanding foam, there is less immediate
loss of chlorofluorocarbon blowing agent and other volatiles. Delivery of
IV-6
-------
JTroversing Mix Headi
Conventional Slab Line
Conveyor
Figure IV-2a. Schematic of traversing foam head machine
Platen
1 Bottom Paper
Conveypr
Figure IV-2b. Stationary head, foam trough machine
IV-7
-------
reactants beneath the foam surface is claimed to achieve slightly greater
foam height from mixtures employing the same 002 an<* chlorofluorocarbon
blowing agents* This type of .foam generation is schematically shown in
Figure IV-2b*l/
Die primary foam generating section of all slab lines is fairly well
enclosed to prevent the escape of highly toxic isocyanates. Openings are
provided at the pour point, v&ile the other end of the foam tunnel is
usually open* Within the foam tunnel, the slab may be subjected to radiant
or steam heat to cure the surface* After several minutes of curing (typi-
cally 10 to 15 min). the foam is tack-free and can be handled. The contin-
uous pour is cut into standard length buns to facilitate handling, trim-
ming, and cutting into the desired thickness sheets. These shorter length
buns (10 to 60 ft) are usually allowed to cool, age, and cure for 12 to
24 or before being fabricated into the desired product. Standard types
of flexible foams include slit sheet, convoluted or contoured slab, and
thin-peeled sheets for flame lamination to textiles. Textile laminating
foams are usually of the polyester type, while the preponderance of flex-
ible foam is of the polyether type*
Although a fairly wide range of flexible foams may be produced by
continuous slab foaming, the vast bulk of production lies in the low and
medium density, soft to firm range* Polyether foams are much more widely
produced than polyester formulations for continuous slabs. Some foams •
are blown exclusively with the 002 generated from the reaction of isocya-
nates with free water. ' -. . .' •
Softer foams with different indentation load characteristics are
produced by incorporating volatile liquids as auxiliary blowing agents*
Most commonly F-ll is used, although methylene chloride may also be ems
ployed* Thus, the chlorofluorocarbon content of the reactant liquid dis-.
pensed onto the conveyor may range from 0 to perhaps 221 by weight for
the "extra supersoft" grade* The most common range of chlorofluorocarbon ..
content is from 8 to 14% by weight of all ingredients. - ^
For purposes of calculating F-ll emissions and potential controls, .;-
a typical low density, soft, one-shot polyether formulation will be as- .
sumed. Table IV-2 shows both a water blown femulation, a flame-Desist ant
foam, and the standard F-ll blown foam composition. :'-.-_• -: -_:.r.
A model plant for the production of flexible polyether slab foam. ...
is described in Table XV-3. .. .,f r..^
W-8
-------
Table IV-2. TYPICAL ONE-SHOT FLEXIBLE FOAM FORMULATIONS
Ingredient ...
Poly ether triol
Isocyanate
Water
Tin catalyst /
Amine catalyst(s)
Flame retardant
Silicone surfactant
F luo ro carbon- 1 1
Standard 1.4 pfc
FC blown!/
100
42.5
3.5
1.75
1.0
-
2.0
13.5
Water blown
medium-density
foam slab£'
100
42.5
3.3
0.45
0.45
•»
1.0
L -
Self
extinguishing
foam6-/
100
43.5
3.5
0.40
0.09
15.0
1.6
9.0
Total
Fluorocarbon percent
Blowing loss (C02t
H20, FC)
Foam yield (7.)
Foam density, lb/ft3
168.5
8.0
22.0
86.9
1.40
147.7
0.0
8.05
94.5
1.80
173.1
5.2
17.5
89.9
i.50
IV-9
-------
Table IV-3. MODEL PLANT - FLEXIBLE POLYETHER SLAB FOAM
1. Continuous pour bunstock machine. Foam line operated 6 hr each pro-
duction day. Foam produced 65 days per year.
2. Pour rate - 450 Ib/min; 162,000 Ib liquids per day.
2
3. Foam profile - 7 ft wide, 42 in. high (24.5 ft section).
4. Foam density - Cured bun before trim; 1.54 Ib/ft .
Trim 1 in. of 3 Ib/ft3' crust; loss of 3.5 Ib/lineal
ft.
Final trimmed foam, 1.40 Ib/ft .
5. Foam system - Standard, open-cell polyether one-shot.
Water 3.5 per 168.5 = 2.1% by weight.
Fluorocarbon 13.5 per 168.5 = 8.07. by weight.
6. Speed of primary foaming conveyor = 12 ft/min
7. Foam tunnel enclosure - 60 ft long x 6 ft high x 8 ft wide.
Opening at pour end - 8 ft x 3 ft high.
Discharge end open - 8 ft x 6 ft high.
Face velocity at openings > 250 cfm/ft2 of opening.
Fan required 20,000 scfm.
8. Transfer conveyor - 60 ft long to cut-off saws.
Ventilation by overhead hood with plastic side curtains.
Fan required 10,000 scfm.
9. Cut-off saw and take-out conveyor - 60 ft long to storage.
Ventilation by overhead hoods.
Fan required 15,000 scfm.
10. Foam storage area - 128 ft x 40 ft x 21 ft high.
Ventilation at 4 cfm/ft2.
Fan required 20,000 scfm.
11. Foam yields
C02 loss 8,300 Ib/day (450 x 0.021 x 2.44 = 23 Ib/min)
FC loss 12,960 Ib/day (450 x 0.08 = 36 Ib/min)
Trim loss 15,032 Ib/day (3.5 Ib/ft x 11.93 ft/min = 41.8 Ib/min
*
Blowing agent losses 21,260 Ib/day; 86.9% bun yield, 140,740 Ib/day
Total weight loss 36,292 Ib/day; 77.6% final foam, 125,708 Ib/day
IV-10
-------
Chlorofluorocarbon Losses -Well designed foam plants making continuous
slab stock usually show exceedingly small chlorofluorocarbon losses in
transfer and handling* No data are available to suggest that inadvertant
vapor losses would exceed 0.5% of the total amount used. For the model
plant using 12,960 Ib of F-ll per day of foam production, losses could
average 60 to 70 Ib/day. Some additional losses are associated with
cleanup* Methylene chloride is often used as the solvent to flush short
sections of the lines and the dispensing head, and to dissolve splashes
of partially cured polymers*
All of the chlorofluorocarbon blowing agent dispensed from the mix-
ing head is lost from flexible foams within a short time. The ingredients
are usually dispensed at approximately 25 to 28°C, or a few degrees above
the normal boiling point of F-ll. Thus, vaporization and loss of chloro-
fluorocarbon blowing agents begins immediately upon discharge from the
mixing head. Depending on the formulation, a "foam line" will be formed
about 10 to 12 in. beyond the pour point where the foam begins to rise.
The heat of reaction volatilizes the F-ll almost completely before the
maximum internal foam exotherm is reached. Maximum temperatures typically
occur after 4 to 5 min (about half-way through the foam tunnel)* The loss
of chlorofluorocarbons exert a cooling effect so that temperatures within
flexible foam buns seldom exceed 190 to 225°F. Additional heat may be
supplied to cure the top skin to a tack-free condition.
In the'model plant, foam is formed at the rate of 292 ff3/min. The
polymer structure of the foam occupies from 2*4 to 3% of the apparent
foam volume, with 96 to 97% vapor volume within the cells*'The standard
formulation employed generates 126 ft3 of F-ll vapor, plus 252 ft3/min
of GO2 at maximum exotherm of 200°F. The combination provides a total
blowing agent vapor volume of 378 ft3/min. Thus, nearly 86 ft3 of excess
vapor is forced from the open cell foam each minute at about the mid-
point of the foam tunnel*
Unfortunately, there is virtually no information in the technical
literature on urethane foams to indicate either the quantity of blowing
agent lost from foams or the concentration of blowing agent vapors in
the hoods or exhaust air* One source estimated that perhaps 807. of the
F-ll had evolved from the flexible slabs by the time it left the cut-off
saw (about 120 ft or 15 min after foaming)*2/
It appears that very few investigators have attempted to analyze
chlorofluorocarbon concentrations associated with foam production.
Ward,!?./ in 1975, measured F-ll vapors in several urethane foam plants.
Samples were only taken in the breathing air occupied by plant personnel.
Because all the plants were working with the relatively toxic isocyanates,
good ventilation is necessary* As seen from Table IV-4, concentrations
IV-11
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of F-ll ranging from 15 to 586 ppm were measured. For a high production
slab line typified by the model plant (Table IV-3), vapor concentrations
near the foam machine average about 170 ppm. These concentrations are
all well below the accepted TLV of 1,000 ppm for F-ll* Chlorofluorocarbon
vapors are much heavier than air and tend to sink to and collect near the
floor level* In many plants* schlieren discloses streams of F-ll vapors
drifting down from equipment and floating across the floor*
Table IV-A. FLUOROCARBON 11 CONCENTRATION IN BREATHING ZONE AIR OF FOAM
MANUFACTURING FACILITIES^
a/
FC-11, ppm v/v—
Flexible foam
Location
High
production
rate
regular
foam
Normal production
rate
Regular Supersoft,
foam foam
Rigid
foam
Panel
produc-
tion
Mix tanks NA NA NA 52
Foam head 178 62-88 113
Expansion > begin 146 31 139 94
"-middle 182 25 198 147
- end 181 24 156 192
Cutting 181 15 130 64
Curing racks 355 280 586 NA
Product storage NA 10 10 12
General building 61 26 47 70
Packaging/shipment 95 10 10 30
Laboratory/office 61 26 47 60
Note: NA - Not available, e.g.. no curing racks, tanks outside, etc*
aj All measurements from corrected POVA readings* Agreement with grab
samples typically within +5%.
IV-12
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For purposes of further analysis it will be assumed that 50 to 60%
of F-ll vapors are evolved from flexible foams by the end of the foam
tunnel; 75 to 807. of F-ll is lost by the cut-off saw; 5 to 107. more is
lost in conveying to the storage racks; and all but 1 or 2% of the F-ll
is dissipated from the foam during aging before splitting. The remaining
1 or 2% is sorbed or dissolved in the polymer, and will be lost to the
air within a few weeks.
What fraction of these chlorofluorocarbon vapors are picked up by
the hoods and ventilation systems that currently are employed? To date
there is no satisfactory answer to this key question.
Dr. John Backus of Hobay reported that analyses undertaken in July
1976uii' gave somewhat puzzling results for F-ll concentrations at vari-
ous points within the foam line and ventilation system. The mass balance
of.F-ll did not agree with chromatographic measurements on grab samples
taken from the line. Most points sampled showed only a few hundred parts
per million of F-ll, while the highest concentration encountered (3,000
ppm) was at a low point in the conveyor. This concentration is lower than
would have been expected if a sizable fraction of the chlorofluorocarbons
are evolved in the first 8 to 10 min of foam formation. Exhaust air con-
centrations apparently were also significantly lower than anticipated.
Note: Additional analyses made since the first draft are now able
to account for about 70% of the chlorofluorocarbon dispersed
from the foam head. Roughly 60% of the total is going into
the ventilation ducts; some 10% more or less is retained
by the foams, past the cut-off saws, and into the storage
area. Hobay engineers and chemists generally believe that,
with suitable redesign of the foam facility, it should be
po.ssible to collect up to 80% of the blowing agent vapors
for some form of treatment.
Clearly, more detailed measurements need to be obtained before it
is possible to specify the extent of engineering modifications that
would be required. The air flow rate must be significantly reduced to
make any form of chlorofluorocarbon recovery system practical.
Two possible explanations for the lower than expected chlorofluoro-
carbon concentrations seem equally likely:
1. F-ll diffuses out of open cell foams slower than has been gen-
erally accepted, and the bulk of chlorofluorocarbon is retained within
the foam cells until well beyond the cut-off saw and into storage.
IV-13
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2. The F-1L vapors are lost from the foam buns, but settle to low
points of the conveyor or tunnel and are partly lost through gaps and
openings in the conveyor system* This latter theory would partly explain
the 170 ppm of F-ll found in the work space near the foam line. If the
chlorofluorocarbons are evolved from the foam buns within the main tunnel,
the overhead hoods and exhaust ducts may not be effective in capturing
these heavy vapors. Further study is indicated to clarify the distribution
of blowing agent emissions during foam production*
Molded Flexible Urethane Foam
The second largest source of chlorofluorocarbon emissions from plas-
tic foams is associated with the production of molded shapes and urethane
parts for furniture, automotive seats and cushions, and resilient padding*
In 1975, it is estimated that 265 million pounds of molded components
and parts were produced (see Table IV-1). Chlorofluorocarbon consumption
was in the range of 14 to 18 million pounds, all of which may be consid-
ered to diffuse into the atmosphere within a few weeks or months*
Molded shapes are produced both by high volume fabricators such as
Fisher Body, Kroehler Furniture, and Ford Motor Company, and also by a
large number of custom molders whose production runs may be fairly small*
None of the molded furniture and automotive production lines begin to
approach the volume of foam produced on continuous slab foam lines.
In addition to the smaller volume of foam produced per plant, sev-
eral other characteristics of molded foam production distinguish molding
from slab production. While most large producers prepare formulations
from basic ingredients and mold one-shot foams, some of the smaller mold-
ers rely upon quasi-prepolymers and complete packaged liquid urethane
systems furnished by compounders.
Foams are dispensed intermittently from the mixing heads into molds,
rather than sustaining a continuous pour as required for slabs. This is
true whether one-shot or prepared reactants are employed. In order to
deliver the required charge for a chair cushion or auto seat into the
mold rapidly so that!the mold can be closed before the foam starts to
rise, pour rates are often fairly high, i.e., 150 to 750 Ib/min.
Until about 1969, the technology for foam molding generally util-
ized the "hot molding" process. Molds were conveyed on pallets through
a pre-heating oven, to the foam dispensing head, where the operator dis-
charged the reactive mixture into the warm mold. The mold was closed
(either manually or automatically by cams along the conveyor line) and
IV-14
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conveyed through a curing oven* After the appropriate cure time, the molds
were opened and the foam parts de-molded at the strip-out point*
Within the past 5 or 6 years many molding operations have switched
to the so-called cold molding process. More highly catalyzed systems are
employed which are capable of complete cure without requiring a curing
oven* The molds are still pre-warmed (largely to minimize surface skin
formation that would occur if poured into a cold mold), and the foam
rises and cures without additional heating* The introduction of deep
molded cushions for automotive seating, which replaced the assembly of
springs, cushion and topper pad, began with the 1971 model year. Today,
most automobile seats are produced by molding the spring wires directly
into deep foam cushions.12/
Chlorof luorocarbon; Consumption in Molded Foams- Because of the diversity
of molding operations it is difficult to define any "typical" plant. How-
ever, several features relating to atmospheric emissions of chlorofluoro-
carbons can be identified.
Due to the smaller size of the average molded foam plant, somewhat
higher losses incident to handling are to be expected. In many instances
up to 1% of the chlorofluorocarbons consumed for foam blowing may be lost
in transfer and mixing prior to dispensing the foam.
Many current mixing heads for molding require a chlorofluorocarbon
flush before and after dispensing each charge of reactants. This is
called lead time, and lag time. For periods of 1 to 3 sec before and
after dispensing the predetermined quantity of ingredients, chlorofluoro-
carbon vapors are vented through the head. Up to 5% of the total F-ll
consumed can be vaporized in this way directly at the mixing head.
Effective removal of isocyanate vapors from the air near molding
lines is required to meet existing health and safety regulations. Be-
cause the discharge of heavy chlorofluorocarbon vapors tends to cause
all volatiles to fall, it is standard practice to provide local or spot
ventilation ports below and behind the dispensing point to scavenge a
large percentage of the toxic isocyanate vapors from the area of the dis-
pensing head.
In the most elaborate and modern plants producing large parts, it
is customary to employ a computer control console which can provide rapid
variation of the foam formulation to accommodate molding a variety of
parts. Successive pallets may, for example, present molds for six arm
rests, four padded sun visors, two bucket seats, four head rests, two
seat backs, and one bench seat for an automobile. In some cases, graded
IV-15
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density parts are molded by delivering a series of pours, containing
different percentages of blowing agents, into various portions of a
single mold. It is common to adjust foam density and firmness by vary-
ing the blowing agent content—even to the point of changing the formu-
lation "on the fly."
The highly catalyzed mixtures cream almost as soon as delivered
into the warmed mold. Once the mold is closed, the only source of chloro-
fluorocarbon emissions is the gradual displacement of air and vapor
through the vent holes as the foam fills the mold cavity. Once foam has
plugged the vents, little or no F-ll is emitted until the mold is opened
after curing.
For molded shapes, the strip-out point is a major source of blowing
agent emissionsJLl.' Despite the best release coatings, it is often nec-
essary to stretch or compress the freshly made part in order to de-mold
it. Here again, ventilation ports are located below the de-molding station.
In the' cold molding process, the parts are usually subjected to a post-
cure heat treatment using radiant heaters for about 1 hr after de-molding.
Additional F-ll diffuses out of the foam parts as they are postcured,
followed by cooling before trimming. In certain types of molded parts,
closed cell foams or incompletely open-cell foams may retain a signifi-
cant fraction of the total F-ll vapor generated during foamiqg. Even-
tually, all of this chlorofluorocarbon will diffuse out of the flexible
polymer. Some parts containing closed cells are subjected to compression
or flexing to crush these cell walls, releasing vapors. .
A schematic diagram of a hot-molding line is shown in Figure IV-3.
A \model flexible urethane foam molding plant is described in Table IV-5.
Chlorof luorocarbon Emissions in Molding Flexible Form - Information re-^
garding the rate of diffusion of chlorofluorocarbons out of molded flex-
ible foams is virtually nonexistent. Because of the large number of mold-
ing plants, and their great diversity, no meaningful measurements of F-.
11 concentrations have been made, either for breathing air or exhaust. .
air streams. We have therefore accepted the best personal estimates of
experienced foam molders, and of molding equipment suppliers. .:•-.-..
For the model foam molding line, each 8-hr shift dispenses a total -.
of 11,520 Ib of urethane system. Since the femulation incorporates 6.5% :
by weight of chlorofluorocarbon, consumption in foam is 749 Ib/shift. :
Blowing losses of 002 anc* chlorof luorocarbon are 10.9% for a molding ..-...,-
yield of 89.1%. Rejected parts and trim scrap are 4% and 2%, respectively.
Per shift, each line molds 5,400 parts. , ~ . .:- -,
IV-16
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Radiant Heat Section
lit Gas-Fired Convection Oven
Burlap
Application
Final Mold
Cleaning
Console
(Digital
Computer)
Pouring Station
l~""l I |
I I I I f~~l
2nd Gas-Fired Convection Oven
1) Stripping Area
2) Mold-Cleaning Area
3) Waxing Area
Sources Reference 3.
Figure IV-3. Schematic layout of a flexible urethane foam molding line ('9iot-molding" depicted)
-------
Table IV-5. MODEL FLEXIBLE URETHANE FOAM HOLDING PLANT
1. Molding lines operate 8 hr/shift. Pallet conveyor delivers two
molds per pallet to foam head. Pre-warmed molds used without
cure oven, i.e., cold molding. Plant operates 230 days per year.
2. Dispensing head is capable of 300 Ib/min, and maintains accuracy
down to 60 Ib/min. Mixing cavity volume is 4 in. • Lead and lag
of 3 sec for fluorocarbon flush.
3. Two molds are filled each 30 sec. Average charge requires 12 Ib
for the two molds.
4. Foam formulation contains 1.8% water by weight. Differing propor-
tions of F-ll are introduced at the head to vary the softness
and density of foam parts. Average F-ll concentration for all
parts is 6.5% by weight.
5. Pouring station ventilated by 2 x 6 ft rear port, extending below
conveyor an additional 3x6 ft. For 300 cfm/ft2, fan required
~ 10,000 scfm.
6. No hood or ventilation provided over conveyor during 16 min cold
cure.
7. Stripping area ventilated by rear wall and under conveyor plenum
totalling 24 sq ft in area. For 200 cfm/sq ft, fan required ~
5,000 scfm.
8. Molded parts of each type are placed in wire baskets on 50-ft rol-
ler conveyor for 1 hr post-cure. Heating tunnel over conveyor
with air plenum beneath conveyor. Effective opening area, 50 sq
ft. For 100 cfm/sq ft, fan required 5,000 scfm.
9. Parts are allowed to cool for 30 min before inspection and trim.
No ventilation provided. Some parts are roll-crushed to open
closed cells. If crushing is performed, the post-cure ventila-
tion system collects a large part of the vapors.
IV-18
-------
The best available approximations of chlorofluorocarbon losses from
the molding process suggest that losses based on total mix poured average:
* 1 to 1*5% F-ll lost in handling and mixing systems prior to mold-
ing.
* 8 to 10% F-ll vaporized dispensing mixture into molds (add ~ 5%
more if F-ll flush of head is used).
* 3 to 5% displaced as foam rises to fill mold (includes any losses
during closed mold cure for cures not employing curing ovens;
add 5% if oven cure is used).
* 25% of F-ll released at de-mold station.
* 40% evolved during post-cure of 1 to 2 hr (deduct 5% if oven
curing is used).
* 15% expressed from foam when flexed or roll compressed to open
closed cells.
* 5 to 7% residual F-ll remains in foam, and will diffuse out within
10 days.
thus, for a molding line consuming 749 Ib of F-ll per 8 hr shift, the
estimated chlorofluorocarbon losses at various stages of molding would
be distributed as shown in Table IV-6.
Other Flexible Urethane Foam Processes
In addition to foam slab production and foam molding, there are a
few other important classes of flexible urethane foams.
Urethane foam has almost displaced hair-jute padding and waffle
latex foams in carpet underlay. The rise of this market has been so rapid
that accurate estimates of production for this use are not available.
In 1975 consumption of prime foam for carpet padding probably exceeded
30.8 million pounds.i/ There are doubts over the Hobay estimate of 93
million pounds..?/ In addition, some 60 to 70 million pounds of rebonded
foam was produced for underlay .i'
IV-19
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Table IV-6. DISTRIBUTION OF CHLOROFLUOROCARBON LOSSES, MOLDED FOAM
(Basis: 1,520 Ib of liquid urethane poured per shift)
Estimated
Processing stage annual losses (Ib)
F-ll lost in materials handling* 2,583
Charging molds 17,222
Chlorofluorocarbon flush* 8,611
Foam rise and cold cure 8,611
De-molding station 43,056
Post-cure \ (may be 68,890
Crush rolls/ combined) 25,834
Remaining in foam parts 8,611
Total emissions 183,418
Note: Losses marked * are in addition to the 749 Ib F-ll per shift dis-
' pensed- as foam ingredients*
•' - . ' * •
Many carpeting manufacturers apply urethane foams directly to the
back of needle-tufted carpets using carefully controlled foam extrusion.
Roto-vinyl yard goods and other 'bard" floor coverings also are produced
with thin, high-resiliency urethane foam backings* Depending upon the
composition of the carpet underlay foam, widely varying figures are ob-
tained for consumption.
We believe that total current output of floor cushioning foams is
about 100 million pounds, or nearly 10% of U.S. production of flexible
urethane foams. Because these foams are processed in large volumes using
continuous lines, the technology is fairly similar to flexible slab foam
production. Lacking valid data on corresponding chlorofluorocarbon usage
and losses, carpet and other floor covering cushions will be treated as
a part of continuous slab foaming for purposes of analysis. ~
:-:. Specialty foams produced in relatively low volumes amount to some -
10 million pounds annually. Scant information is available concerning
reticulated flexible foam, self-skinning flexible urethanes, reinforced
flexible foams, and medium density, impact-absorbing, low-resiliency- - - ' - •
padding. These foams consume relatively small amounts of chlorofluoro-
carbons, and will not be analyzed in detail. For convenience, these foams
will be considered as part of molded foams. ... . : -
IV-20
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RIGID URETHANE FOAM PRODUCTION
In 1975 rigid urethane foam production reached 340 to 383 million
pounds. This represents only 25 to 30% of the combined total for flex-
ible and rigid urethane foams. The approximate distribution of rigid
foam for the latest year is shown in Table IV-7.
Table1 IV-7. U.S.. RIGID FOAM CONSUMPTION - 1975
(millions of pounds)
Modern Plastic:
Building construction
Refrigeration appliances
Transport carriers
Industrial (tank and pipe)
Total thermal insulation
(312.4) 81.67.
133
70
36
44
(283) 83.2%
Furniture parts
Packaging
Marine and flotation
Miscellaneous
Total
382.8
20
12
10
15
340
More than 80% of all rigid urethane foam is used as thermal insula-
tion. Chlorofluorocarbon blowing agents are considered essential to attain
satisfactory insulating foams. Therefore, more than two-thirds of the total
chlorofluorocarbon consumption for plastic foams is used to produce rigid
urethanes.
By far, the largest use of rigid urethane foams is in building con-
struction. There has been a substantial increase in rigid foam use since
the cost of energy has risen sharply, and the concern for energy conserva-
tion, has grown. Other important insulating uses include refrigerators,
freezers, transportation carriers (truck trailers and freight cars) and
industrial applications such as the insulation of tanks and pipelines.
For insulation uses, urethane foams are typically produced at densities
of 1.6 to 2.2 lb/ft3 (pcf); and virtually all of the insulating foams
employ chlorofluorocarbon blowing agents.
IV-21
-------
Other uses of rigid urethane foams (e.g., packaging and dunnage,
boats and flotation, and molded structural parts) may or may not employ
chlorofluorocarbon blowing agents. In particular, the medium to high
density (8 to 26 Ib/ft^) rigid urethane moldings have grown rapidly in
application between 1967 and the present. These molded parts replace
wood in furniture, television cabinets, decorative interior profiles,
and a variety of industrial parts. In the higher density ranges little
or no chlorofluorocarbon blowing agents are employed.
Because of the diversity of uses for rigid urethane foams, a wide
range of processes and techniques for production have been developed.
Only those processes that employ chlorofluorocarbon blowing agents will
be considered.
Since no detailed statistics on production in different forms are
regularly collected, there is considerable uncertainty regarding the
proportion of rigid foams produced by different processes. By pooling
estimates obtained from trade sources, broad estimates of current out-
put for four major categories of rigid foam production have been derived.
For purposes of analysis, the data below lists the four types of
rigid foam processes that will be discussed. Estimated production for
1975 is given for each category both in millions of pounds, and as a per-
centage of total rigid urethane foams (excluding high density furniture
foams).
APPROXIMATE DISTRIBUTION OF RIGID URETHANE FOAMS BY
PRODUCTION PROCESS
1975 Output
(million Ib)
Foam type 2/ I/ Rigid foam
Boardstock, slab, billets, logs 96-127__ 28-33
Structural foam core panels ' 42-57 _ 12-15
Foam-in-place cavity (in-plane) 106-128^ 31-33
On-job-site foam application 36-48 |; 11-13
All rigid foam£/ 280-360^ 82-126
Reported by traded' 320-348
a/ Furniture structural foams excluded.
IV-22
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Reaction injection molding of furniture parts and other high den-
sity "structural" foams will not be considered because the use of chloro-
fluorocarbon blowing agents for high density foams is insignificant. A
small volume of low density rigid urethane foam is produced by molding
to shape* Typical uses include pre-fozmed pipe lagging, imitation wood
beams or moldings, and packaging applications. Production processes are
sufficiently similar to boardstock that these molded parts will be treated
as part of slab and billet production*
Each of the four types of production techniques possess many sim-
ilar aspects, plus certain features directly related to chlorofluoro-
carbon consumption and atmospheric emissions*
Rigid urethane foams are prepared by mixing two or more reactive
liquid ingredients together. The chemical reaction which results forms
a polymeric material which entraps gas bubbles to provide the desired
cellular structure. The gas required for foaming is derived from carbon
dioxide released during the polymerization reaction, or from the vola-
tilization of an added blowing agent vaporized by the heat of reaction.
For rigid foams, standard practice is to formulate "liquid systems"
which require the mixing of only two or three streams at most. Large
volume producers purchase basic ingredients and prepare their own sys-
tems. Many smaller foam producers prefer to purchase prepared liquid
systems offered by a number of resin compounders.
The liquid ingredients are mixed in a foam machine with a pumping
unit capable of accurately metering the components through a continuous
mixer which blends the components uniformly. Preparation of the urethane
system components, metering and complete mixing are all critical to the
proper manufacture of polyure thane foams* Machinery for the proportioning
and dispensing of urethane foams is highly developed, with equipment
being offered by 48 manufacturers. The basic forms and variations among
commercially available urethane foaming machinery has been reviewed re-
cently by JohnsonJLft/ and will not be considered in detail. After the
mixture is dispensed from the metering and mixing head, the method of
application, and the means used to contain the foaming mixture, differ
widely according to the application. These factors in turn influence
the choice of blowing agent and the formulation of the urethane system.
Rigid urethane foams can be manufactured by batch processes, by a
continuous slab or "bun" process, by foaming or frothing in place, and
by spraying. The four basic dispensing methods for rigid urethane foams
are pour, froth, spray, and injection. Holding and casting are both gen-
erally considered as a form of foam pouring. The frothing process can
IV-23
-------
be applied either to foam pouring, or froth spraying. Thus, the basic
dispensing methods can be divided into two broad classes—spraying and
pouring.
In the U.S., the continuous slab production and foaming in place
are the most common* Continuous production of rigid foam board stock
(commonly used for building insulation) involves pouring the liquid mix-
ture as a thin layer onto a continuously moving conveyor where it ex-
pands to form a continuous block of foam* After oven curing, the foam
may be sliced to specific thicknesses by'a variety of sawing methods.
An alternative of increasing importance involves panel production through
the continuous application of surface skins (metal, paper, or plastic
laminates) with the panel expanding to standard thickness. Foaming in
place involves pouring the liquid mixture of foam components from the
dispensing head directly into a cavity. Details of this process are pre-
sented later in the subsection concerning rigid foam-in-place cavity
filling.
Sprayed polyurethane foams are often used for on-site application
of rigid thermal insulating foams. The liquid urethane ingredients emerge
from the mixing head and are sprayed onto the desired surface to expand.
As in pouring operations, froth spraying has become a convenient method
of achieving the desired urethane thickness and maintaining control over
the desired density and skin thickness.
The most important characteristic of many rigid urethane foaming
processes is that the blowing agent vapors are trapped and retained in
the finished foam, with only minor losses of chlorofluorocarbon vapors
during production. The exact quantity of blowing agent losses depends
upon foam stability during rise, percentage and type of chlorofluoro-
carbons used, the peak exotherm temperature achieved within the foam,
and the extent of mechanical rupture of foam cells after curing the .
foam.
Formulations for rigid urethane foams typically contain from 12 to
16% by weight of chlorofluorocarbon for foam densities ranging from 1.6 .
to 2.3 Ib/ft . Often no water is used, or the moisture content is kept..
close to zero, so that the insulating foams are primarily expanded, by.
chlorofluorocarbon vapors to achieve low thermal conductivity. _._..•;:_...-
"-The use of chlorofluorocarbons in concentrations much greater than ;;
6% by weight tends to reduce foam stability during the rise. Since rigid :
urethane-foam systems typically contain about twice as much chlorofluoro- -
carbons as found in flexible formulations, considerable care must be taken
in selecting surfactants and other additives to achieve as much. foam, starr.
bility as possible. Even at best, freshly rising rigid foams are tender,
IV-24
-------
and subject to collapse if stressed or disturbed. Collapse of foam bub-
bles before gelation releases part of the blowing agent vapors*
While trichlorofluoromethane (F-ll) is the blowing agent most widely
used, some suppliers recommend proprietary chlorofluorocarbon blends that
offer a wider range of vapor pressures, and are claimed to generate more
uniform and consistent foam structures.
For certain types of high vertical rise foaming, and for many cav-
ity filling operations, froth foam pouring or spraying is common. In
addition to the customary F-ll, up to 6% of low boiling F-12 is intro-
duced into the foam mixing chamber* When discharged from the mixing
head, the foam immediately pre-expands into a froth, followed gradually
by further expansion as the heat of reaction vaporizes the F-ll.
Blowing agent loss in foaming is also affected by the rate of the
polymerization reaction. A slow reaction, with long gel times, permits
some cells to collapse, thus reducing foam volume and releasing blowing
agents. Extremely reactive foam systems, on the other hand, create high
internal foam temperatures. In some cases, excessive peak exotherms re-
sult in large internal bubbles, some browning of the polymer, and pos-
sible expulsion of blowing agent vapors if the volume of vapor at peak
temperature exceeds the available cell volume after gelation.
The four types of rigid foam production processes—boardstock or
billets, structural foam core panels, cavity filling, and on-site foam
application—are sufficiently similar in most respects, that only those
differences which determine or influence the consumption of chlorofluoro-
carbons, and the distribution of chlorofluorocarbon emissions during
production need to be considered.
Model Rigid Urethane Foam Boardstock Plant
Boardstock in planks, sheets, billets, and foam logs, is produced
on high volume continuous foam machines quite similar to the ones used
for flexible foams. Sometimes the identical line may be used to produce
both types of foams. The building supply industry, which generates much
of the rigid foam, has evolved into a fairly specialized segment, usu-
ally producing rigid foam products exclusively. In 1972, the principal
boardstock manufacturers accounted for sales of an estimated 75 million
pounds of foam; equivalent to 450 million board feet of product. The
substantial increase in rigid foam consumption in building insulation
since 1972, probably indicates that some 115 million pounds or 690 mil-
lion board feet of rigid slab and board were consumed in 1975.
IV-25
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The scope of "boardstock" for purposes of this analysis is taken
to include all rigid urethane (and polyisocyanurate) foams produced as
slab sheet or billet, without facing substrates (raw board), or employ-
ing paper or other permeable skins on the finished foam boards. (Panels
having metal, plastic, foil, or other Impermeable skins are included with
structural panels*) The characteristic parameters of the model boardstock
line are shown in Table IV-8.
Chlorofluorocarbon Losses in Boardstock Production - Experienced producers
of rigid foam sheets and billets report bun yields of 96 to 99 Ib for each
100 Ib of liquids dispensed from the mixing headJt5./ Blowing agent losses
during creaming and foam rise vary with seasonal temperatures; however,
an estimate of about 97% yield indicates roughly 2% loss of chlorofluoro-
carbons plus 1% of 002> water> and other volatiles.
This estimate of Chlorofluorocarbon loss on the foam machine is en-
tirely consistent with the calculated vapor volume losses for the model
foam line (i.e., 141 ft3 of cell volume will hold up to 36.9 Ib/min of
the 42 Ib/min of F-ll dispensed; equivalent to a loss of 12% of initial
chlorofluorocarbons). Chlorofluorocarbon vapor concentrations in the
plant air near rigid foaming machines have been measured at 150 ppm, which
also indicates that the major source of F-ll losses is near the initial
foaming point (see Table IV-4, page 1Y-12).
There is virtually no further loss of chlorofluorocarbons as rigid
foam cools and ages. During this period of time, air and other vapors
are diffusing into the foam at a slow rate.
Sawing and cutting foams to size, of course, opens cells and ex-
poses additional surface to the air. Some production lines incur trim
and saw kerf losses of 8 to 10% of initial bun weight. At the time of
sectioning, foams may be up to 1 to 2 days old, and the foam cells con-
tain approximately 57 to 62 mol % F-llJ£/ Therefore, some 4.6 to 6.2%
of the Chlorofluorocarbon remaining in the foam cells is emitted to the
air in cutting and trimming the foam. This is the equivalent to 3.9 to
5.3% of initial Chlorofluorocarbon dispensed as foam ingredients.
Summarizing Chlorofluorocarbon losses for the model size plant (based
on 7,560 Ib of F-ll used per shift):
* Material handling 1% or 76 Ib/shift _:
* Foaming machine 12-14% or 907-1,058 Ib/shift -
* Trim and cutting 4-5% or 302- 378 Ib/shift •_-_ ..,
Total plant losses 1,285-1,512 Ib/shift
IV-26
-------
Table IV-8. MODEL URETHANE FOAM BQAEDSTOCK PLANT
1, Plant operates 6 hr/day, 200 days/year.
2. Pour rate, liquids: 150 Ib/min.
3. Slab profile: 8 ft wide x 1,25 ft high: (10 ft cross section).
4. Foam density: 2.0 lb/ft3 finished product; 94.5% closed cells.
5* Conveyor speed: 7.5 ft/min in 50-ft tunnel; ventilation rate:
5,000 scfm.
6. Chlorpfluqrocarbon content: 14.07. by weight (2l Ib/min).
7. Foam time: 3 min; tack-free: 4-6 min; cure time: 8-10 min.
8. Maximum exothexm: 260°F at 4-5 min.
9. Foam yield factors:
97 Ib of slab per 100 Ib liquids dispensed,
Blowing losses: 2 Ib of FC plus 1 Ib H^O. C02, and others,
Vapor volume of foam cells: 97% of 75 ft^/min = 72.8 ft3, and
Volume of FC vapor retained at 260°F: 68.7 ft3.
10. Trim and sawing losses = 10% of slab.
Dust collection system only; no fume ventilation.
IV-27
-------
Ventilation systems for rigid urethanes are often less stringently
designed, because less volatile types of isocyanates are used* Thus, the
efficiency with which chlorofluorocarbon vapors from foaming are collected
into ducts may be lower than would be typical for a flexible foam produc-
tion line.
Structural Foam Core Panel Production
Rigid urethane foam is produced in substantial volume as finished
or semifinished construction components. The best industry estimates are
that from 45 to 60 million pounds of urethane foam consumed in 1975 in
the form of pre"manufactured structural foam core panels and building
components* Major uses include:
* Curtain wall exterior panels.
* Prefabricated wall modules,
* Exterior and interior doors,
* Roofing,
* Prebuilt warehouses and coolers,
* Truck panels, and
* Steel building components.
The various production methods comprise foam core lamination to struc-
tural facings, vertical foam-in-place, horizontal foam-in-place, and con-
tinuous laminate production. Lamination of surface substrates over foam
stock cores to form structural components represents further processing
of boardstock. Both vertical and horizontal foaming-in-place in doors . .
or panels may be treated as a variation on cavity filling operations. ..
This section considers a variation on rigid boardstock production, namely
continuous foaming: between rigid skins to produce load bearing structural .
laminates. . _,; . .;:-....
----- Facing:materials most often include coil steel, embossed or prefin-
ished aluminum,rhardboard, plywood, cement-asbestos board, gypsum drywall-
board, reinforced plastics, and high-pressure decorative laminates.-Figure:
-IV-4 illustrates a typical continuous panel line using steel skins-on -.::
both faces. It: is clear that continuous panel production is a modlf ica*:
tion of free-rise rigid slab techno logy .
IV-28
-------
STORAGE
COMPONENT
STORAGE
COMPONENT
B
to:
METERING PUMPS
FLEXIBLE
COVERING
MATERIAL
(top)
POUR HEAD
lx
. X
Q
ING
.AD '
->
d H
u
1
O
• AUJUST
X- " — >•
J \ O'V
V RISING FOAM \
ABLfc PINCH HULL!
OVEN \\
(side view) x
130*-180°F 'I
FLEXIBLE
COVERING
MATERIAL
(bottom)
• OVEN
[(top view)
•V
STACKING AREA
AUTOMATIC
STACKER
MEASURING AND
CUTTING DEVICE
plane now rotated 90*
Figure IV-4. Sandwich panel production - continuous process
-------
Principal features which differentiate panel production from board-
stock are:
* Larger number of producers,
* Smaller output per plant,
* Lower urethane pour rates,
* Reduced chlorofluorocarbon losses in foaming,
* Essentially zero chlorofluorocarbon loss after panel is formed.
There are so many panel fabricators using diverse production pro-
cesses that no adequate data are available regarding chlorofluorocarbon
consumption and losses. The preceding boardstock model plant will be
used with the following modifications assumed for a plant manufacturing
425 panels per shift as shown in Table IV-9. With these changes, the
chlorofluorocarbon consumption and emissions for the plant can be esti-
mated.
Chlorofluorocarbon Usage and Losses
* Total consumption 1,746 lb/shift
* Losses in materials handling 18 lb/shift
* Loss of chlorofluorocarbon 26 lb/shift
in foaming
* Contained in panels 1,702 lb/shift
Rigid Foam-In-Place Cavity Filling
Foaming in place involves pouring the liquid mixture of foam com-. .
ponents from the dispensing head directly into a cavity (such as the. .-
walls of a refrigerator or boat hull). The chemical reaction causes, the
blowing agent to expand, and the foam completely fills the cavity. Con-. :-
siderably accuracy and uniformity is required in dispensing the urethane
into cavities and molds. Each volume of the liquid urethane deposited .. .;
expands 30 times in volume and therefore must be accurately measured, and ;
precisely placed within the mold or cavity in order to insure accurate: : .
filling, and avoid excessive pressure on the sides of the mold or. product.;,;
IV-30
-------
Table IV-9. MODEL FOAM CORE STRUCTURAL PANEL PLANT
1. Panel line operates for 6 hr per 8-hr shift, 240 days/year.
2. Pour rate: 40 Ib of urethane system per minute.
3. Panel size: 5 ft x 9 ft x 3.5 in. thick; foam thickness: 3.0
in. x 5 ft wide (1.25 ft2 cross section).
4. Foam density: 3.0 lb/ft3; 13.3 ft3/min.
5. Conveyor speed: 10.6 ft/minj foam tunnel covers first 10 ft;
ventilation provided by 5,000 cfm fan.
6. Chlorofluorocarbon content of system: 12% by weight; 4.8 Ib/min.
7. Foam yield 98.5% of liquids dispensed; chlorofluorocarbon loss during
foam rise accounts for nearly all weight losses, i.e., ~ 1.5% or
0.072 Ib/min.
8. Material handling chlorofluorocarbon losses > 1% of consumption.
IV-31
-------
The froth process Introduced in the early 1960 (s is being used to
an increasing degree to minimize these problems. The frothing process
• involves the addition of another blowing agent, usually fluoro carbon -12
(alternatively, F-114 or F-115 may be used) injected directly into the
mixing head. The mixing head operates at a pressure of about 100 psi to
keep the frothing agent liquid until it emerges from the dispensing noz-
zle into the cavity or mold. The reaction and further expansion of the
foam roughly doubles the froth volume, thus filling the cavity or mold
without excessive pressures, and permitting more accurate filling of
cavities. .
The frothing pour process has become increasingly important for cav-
ity and mold-filling applications; Refrigerators and freezers represent
one of the most important applications of rigid froth pour-in-place foams.
Thin-wall refrigerators can use approximately one-half the usual insula-
tion thickness, thus resulting in up to 35% greater interior capacity.
The average foam usage is 9 to 12 Ib/unit. Froth foam is placed in the
cavity between the refrigerator liner and the outer steel shell to bond
the two surfaces together and completely fill the cavity.
O
When notifrothed resins are used to generate foams of 2 Ib/ft* den-
sity, complex Jigs and supports must be used to contain the molds or
sheets and prevent distortion during foaming. Pressures developed by
foaming in cavities 1 to 2 in. thick may reach 2.5 to 3.8 psi on the
walls of the mold, because of the high expansion ratio, and because
about 5% excess urethane must be added to insure a complete foam fillj=§'
When froth poured foam is used, the foam expansion exerts only about
0.4 psi on the surrounding walls. Simple, flat walls on building panels
or mobile homes and trailers require only minimum supports and jigs—
usually plywood support is adequate. Refrigerator doors containing
shelves, separators, and egg trays may require more complex jigs and
fixtures. The foams have sufficient flowability to fill narrow and com-
plex mold cavities such as thin shelves and egg frame protrusions of a
vertically filled refrigerator door, but small holes must be positioned
to allow the escape of air during the foaming process. These holes seal .
themselves as the foam gels. ..-..-.
Because the jigs and support fixtures for foaming to fill a refrig-_-
erator shell or the double hull of a pleasure boat often weigh several::.-.
times as much as the product itself, many cavity filling lines are.de?. -. .
signed with several clamp and Jig stations served by a single foam dis-.--
pensing head. It is easier to bring refrigerator shells to the fixtures,:
than to attempt -to deliver fixtured cabinets to a stationary foam head. :.
3V-32
-------
Factory poured foam and froth for cavity filling applications ac-
counted for the following production volumes in 1975.
Poured and Froth Foamed-In-Place Rigid Urethane» 1975
(millions of pounds)
Total rigid Foamed-in-place
urethane foam Froth Total
Refrigeration appliances 72.6 40.0 66.8
Insulated housewares,
picnic coolers, etc. 11.1 3.3 . 8.4
Boats and marine flotation 13.8 6.2 12.4
Insulated transport car-
riers 48.4 23.2 38.7
Automotive and aerospace 9.5 1.5 4.9
Building components and
modules
Miscellaneous
Total 200.7 84.4 163.8
Because of the wide acceptance of froth foam, cavity filling in
deep freezers, refrigerators, boat hulls, and truck trailers, of the
indicated 164 million pounds of foam, pre-frothed foam filling ac-
counted for about half of the total foaming-in-place.
Urethane systems for froth pouring as thermal insulation foam suit-
able for a deep freezer typically contain from 11 to 12.5% F-ll with
from 3 to 6.0% F-12 as blowing agents. The maximum F-12 content is 6%
by weight; any excess will be lost without aiding the process.
Model Foam-In-Place, Cavity Filling Operations - An appliance cabinet
foam insulation line will be used as typifying current practice in cav-
ity foam filling. Similar types of installations are used for boats,
truck trailers, and many other foam-in-place applications. The charac- '••
teristics of a model foam-in-place plant operation is shown in Table IV-
10.
The largest refrigerator manufacturers such as Frigidaire, Whirlpool,
General Electric, and Westinghouse each consumed about 6 million pounds
of urethane systems in 1975. Smaller plants of which Amana, Philco, Gibson,
Norge, and Admiral are fairly typical, each generate approximately 1.5
to 2 million pounds at current production levels. Each plant may have
several cabinet insulation filling lines.
IV-33
-------
Table IV-10. MODEL FOAM-IN-PLACE, CAVITY FILLING PLANT
(FREEZER INSULATION LINE)
1. Plant produces 4% of U.S. freezer output for 1975, i.e., 2,457,000
freezers x 0.04 = 98,300 units.
2. Plant operates 250 days/year; one 8-hr shift per day; daily output
- 393 freezer units, \t». 49 units/hr.
3 3
3. Freezer .sizes range from 14 ft (26% of output), up to 22 ft (34%
of output). Average foam insulation requirement for all models,
17.2 Ib/unit.
4. Foam requirement - 1.691 million pounds per year; 6,763 Ib/day.
5. Cycle to jig cabinets and doors in fixtures, froth-fill, cure foam
and remove from fixtures ~ 20 min. Each support fixture is used
three times per hour.
6. Insulation is applied on three foam lines, all served from one ure-
thane system preparation unit. Two cabinet lines, each have eight
sets of fixtures. One door line uses 16 support fixtures. Total
throughput averages 48-50 insulated units per hour. Ventilation
for the three filling stations provided by common ductwork with
10,000 scfm fan.
7. Urethane system contains 12.0% F-ll, plus 4.5% F-12. Each cabinet
requires an average of 10.2 ft3 of foam at 1.7 Ib/ft^ density.
Total chlorofluorocarbon use in foam is 278,975 Ib/year.
8. Chlorofluorocarbon vapors emitted from froth filling: 10% of F-ll
dispensed (0.206 Ib/unit); 35% of F-12 dispensed (0.271 Ib/unit);
chlorofluorocarbon vapors - 0.477 Ib/unit, total 46,919 Ib/year.
9. . Chlorofluorocarbon losses in mixing, handling, and transfer - 1»2% .
of consumption in foam ~ 3,348 Ib/year.
IV-34
-------
On-Site Application of Rigid Urethane Foams
Rigid insulating urethane foams are applied on the job site by a
large number of contractors, as well as by industrial plants and trans-
portation firms* The major uses include building construction, insula-
tion of industrial tanks, foam coating of railway freight and tank cars,
roofing and the construction of thermally insulated pipelines. These
foams are nearly always applied by foam spraying, although a small vol-
ume of froth-poured wall cavities are filled on-site. An increasing num-
ber of petroleum pipelines are being insulated in the field, either
using portable foam application machines, or by pouring foam into an
annular, .shield, around t±e pipeltoe^s it re^ Large
ship'insulation and barge flotation jobs represent a slightly differ-
ent category because of the very high volumes involved, and the high
rates of pour required.
There are currently some 200 foam contractors with 176 firms form-
ing the membership of the Urethane Foam Contractors AssociationJL2/ In
addition, information compiled by the UFCA shows that more than 650 firms
currently own foam spray application equipment, and purchase urethane
foam systems of the class used for job site foaming.
There are no industry estimates of the total poundage of urethane
foams applied on-site. It is not likely that 1975 consumption would
exceed the following estimates:
On-Site Foam Insulation, 1975
(millions of pounds)
Total rigid On-site
urethane application
Building construction;and roofing 133 16
Transport carriers 36 9
Industrial tank and pipe 44 14
Marine and flotation 10-13 4
Miscellaneous 8-15 _3_
Total 266 46
The urethane systems employed for sprayed-on foams are extremely
reactive, so that a gelling polymer structure is produced almost im-
mediately on leaving the spray head. A gel time of 6 to 12 sec is fairly
typical for sprayed walls or roof decks. Chlorofluorocarbon content
ranges from 8 to 12% for sprayed foams, and up to 10 or 12% for the mi-
nor quantity of froth sprayed and poured foams.
IV-35
-------
Application contractors report that the foams set so rapidly that
there is no visible evidence of foam bubbles rupturing as the foam ex-
pands on the surface. Because the atomized system is broken up to expose
a large surface area for the fraction of a second between the run and
the surface, some chlorofluorocarbon evaporation is to be expected* The
consensus of two application contractors^/ and two equipment suppliers^!/
is that no more than 10% of the blowing agent used escapes to the atmo-
sphere* These estimates specifically include all overspray losses in ap-
plication* (Spraying overhead on ceilings can result in up to 15% weight
loss; vertical surfaces and roof tops average 96% foam yields if sprayed
when wind is not a problem*) There is essentially no on-site loss of
chlorofluorocarbons due to handling and preparation of the mixed system
because virtually all applicators purchase prepared systems in tanks or
drums, ready for field spraying* Losses by large suppliers probably av-
erage less than 0*5% of the chlorofluorocarbon content*
Because low volatility isocyanates are employed, there are no re-
ported problems with toxic vapors, and special ventilation is not nor-
mally provided for jobs where foams are applied in unconfined work places*
A few contractors have attempted to use plastic tents or inflatable en-
closures to permit spraying under less favorable wind conditions (for
example, the New Orleans Super Dome)* However, the use of enclosures is
not at all common*
, " *
Estimation of Chlorofluorocarbon Losses - Due"to the extreme diyersity
of on-site foaming, the emissions from the entire sector will be esti-
mated rather than attempting to define a model plant. The maximum emis-
sions of chlorofluorocarbons from on-site rigid urethane foams (both
sprayed and frothed) is estimated as follows:
Total: 46 million pounds of foams
40 million pounds sprayed at 12% F-ll
6 million pounds frothed at 10% F-ll plus 4% F-12
Chlorofluorocarbon losses:
F-ll 540,000 Ib/year
F-12 48.000 Ib/year ..
Total 588,000 Ib/year :-.-.....
IV-36
-------
SUMMARY OF GHLORDFLUOROCARBON CONSUMPTION AND MISSIONS
The foregoing discussion of chlorofluorocarbon usage and processing
losses may be summarized by comparing the quantities consumed din the six
basic processes. Two summary tables are provided for this purpose. Table
XV-11 compares the annual foam output for each model plant (except on-
site foams which are for the entire industry sector), showing total
usage, and emissions at various stages of production and processing. All
chlorofluorocarbons used in making flexible foams is emitted to the atmo-
sphere fairly promptly. The great preponderance of chlorofluorocarbons
trapped in rigid foams will be retained for many years. Perhaps two-thirds
of the quantity initially found in 24-hr-old rigid urethane foams will be
retained for the useful life of these foams.^/ On final destruction of
the building, deep-freeze or other insulated product, the entrapped chloro«
fluorocarbons will be released. At least for a number of years into the
future, chlorofluorocarbons consumed in insulating foams represent a
storage depot, contributing only minor amounts of atmospheric emissions.
The second summary, Table IV-12, presents a reconciliation of total
chlorofluorocarbon losses from each type of foam process. By using esti-
mates of 1975 output of each foam and the fraction of this production
blown with chlorofluorocarbons, the equivalent number of model plants
required can be derived. For example, the indicated 32 to 38 flexible
slab lines using chlorofluorocarbon blowing agents is of the right mag-
nitude. About 25 producers or plants running continuous foam machines
can be identified. There doubtless are others, and some plants operate
more than one foam line, but some 30 to 40 plants of the size specified
appear to be realistic.
Total indicated chlorofluorocarbon emissions for 1975 are given in
the last column of Table IV-12. The 30 to 40 million pounds from flexible
foams is slightly lower than the estimate of 35.4 million pounds for 1973
prepared by A. D. Little.23/ one reason for part of the decline has been
the increasing use of methylene chloride as an auxiliary blowing agent
for less critical types of flexible urethane foams. Thus, only some 33%
of flexible foams were blown with chlorofluorocarbon agents in 1975 versus
nearly 42% in 1973. The present estimate of emissions from rigid foams
totaling 6.8 to 8.5 million pounds in 1975 is also lower than the 9.0
million pounds indicated by A. D. Little. Here the difference arises from
our use of slightly lower estimates of losses in foam production.
The general agreement of these independent estimates suggests that
the allocations of emissions by stage of processing, as given by Table
IV-11, form a sound basis for giving preliminary consideration to the
technical feasibility of recovering chlorofluorocarbons from foams.
IV-37
-------
I«ble IV-11. CHLOBOFLUOKOCAHBON CONSUMPTION AND EMISSIONS, UBETHAN8 FOAMS
5!
fc
Foam output
Type of foam, process of plant
fmoifet Plants, see text) (million Ib/vr)
Flexible, continuous bun or slab 8.17
Flexible, molded shapes 2.22
Rigid, continuous boardstock 9.43
Structural, foam core panels 3,40
Foam-ln-placa, cavity filling 1.69
Rigid foams, applied on-stte 46.00
(entire Industry segment )£/
Total FC Mixing and Foaming Processing Processing Processing PC retained Total PC
consumption handling loss loss loss - 1 loss - 2 loss - 3 In product emissions
(Ib/vr) (Ib/vr) (Ib/vr) (Ib/vrH/ (Ib/vrW (lb/vr)£/ (Ib/vr) (Ib/vr)
846,612 4,212 421,200 168,480 '84,240 151,632 16,848^ 846,612
183,418 < 8,611 17,222 43,056 68,890 25,843 8,611^ 183,418
1,527,120 15,120 216,000 - - 60,480 1,235,500 291,600
418,847 4,147 51,840 - - 362,880 55.987
282,323 3,348 46,919 - - - 232,056 50,267
5,640,000. - 588,000 ... 5,052,000 588,000
lJ Processing losses are (1) secondary conveyors.
by Processing losses are (2) bun cut-off station and conveyor.
£/ Processing losses are (3) aging and cutting to finished sites,
d/ Chlorof luorocarboa remaining In flexible foams at shipment diffuse to atmosphere within 30 days.
£/ Lead and lag chlorofluoroearbon flush of mixing head.
_£/ Total on-slte application sector for U.S.I not directly comparable with preceding model plant figures.
-------
Table IV-12. ESTIMATION OF CULOBOFUJOBOCARBON EMISSIONS FROM UBETHANE FOAMS - 1975
t
10
Type of foam, proces?
Total U.S. flexible urethane
Flexible, continuous bun or slab
Flexible, molded shapes
Total, flexible
Total U.S. rigid urethane
(Total rigid, except furniture)
Rigid, continuous boardstock
Structural foam core panels
Foam-ln-place, cavity filling
Rigid foams, applied on-slte
U.S. output
(million Ib)
924^-1,044^
j60S/.775b/
264S/-269!!/
34ofe/-383fi/
320fe/-3482/
96^-1 27£/
42J/-57S/
106^-1 28^
36i!/-4s£/
Percent
FC blown
33
30
95
90
85
95
FC blown
(million Ib)
- 218-256
79-82
91-121
38-51
90-109
34-46
Model plant
output
(million Ib)
8.17
2.22
9.43
3.40
1.69
46. 00^
Total FC
emissions
olant (Ib/vr)
846,612
183,418
291,600
55,987
50,267
588,000-S'
Number of
olan^ft r$gu,^red
27-31
36-38
10-13
11-15
53-65
S00-600£/
Indicated total
U.S. emissions FC
(million Ib/vr)
22.8-26.2
7.0-7.3
29.8-33.5
2.9-3.8
0.6-0.8
2.7-3.3
0.6
(Entire Industry segment)!/
Total, rigid
6.8-8.5
Totals, all urethanes
a./ Based on Modern Plastics. Reference 1.
J>/ Based on Mobay survey. Reference 2.
c/ Estimated using Modern Plastics, see Table IV-8.
d/ Estimated using Mobay survey, see Table IV-B.
ej Total on-slte applied foam, not strictly comparable with model plants above.
-------
POLYSTYRENE AND POLYOLEFIN FOAMS
Use of chlorbfluorocarbon blowing agents in other foams is signifi-
cant only for three types of plastics:
* Polystyrene sheet and film (extruded),
* Polyolefin medjjm_density flexible foams, juid_
* Polystyrene boardstock made for thermal insulation.
Foamed polystyrene sheet and films are extruded from high molecular
weight "crystal" resins for products such as egg cartons, disposable
serviceware, cushioning sheets, and packaging products. Typically the
blowing agent is iso-pentane, or a mixture of pentanes with chlorof luoro-
carbons 11 and 12* Total blowing agent ranges from 5% to as high as 8%
of the extrusion mixture* In 1975 some 539 million pounds of extruded
foam sheet was produced* Consumption of chlorofluorocarbon blowing agent
was not reported, but may be estimated at less than 7 million pounds.
Blowing agent vapors diffuse fairly readily out of the thin and flex-
ible foamed sheet* None of the producers contacted had attempted re-
covery of blowing agents* Because the sheet is extruded from ring die,
pulled over a sizing'and cooling mandrel,, then slit and wound into rolls,
there is little time or opportunity to collect vapor emissions at the
extruder. The possibility of recovery from the wound rolls has not been
explored so far as could be learned.
Styrofoam extruded boardstock for thermal insulation is produced
in the U.S. exclusively by Dow Chemical Company. Patented mixtures of
methyl chloride and chlorofluorocarbons are employed as blowing agents.
It is essential that the halogenated vapors be retained within the foam
to provide a low thermal conductivity. Therefore the vapor concentrations
at the point of production are quite low (well below 1,000 ppm at all
times and locations) .^ft/
Consideration has been given by Dow ~ to vapor recovery. Carbon ad-
sorption, compression-condensation, and use of the relatively new "imbiber
beads" (developed for collecting organic spills) have been evaluated. At ~_
present hone of these approaches are considered technically feasible for
low vapor concentrations. All of the recovery techniques considered are ::
-judged to be impractical for economic reasons as well. Chlorofluorocar- _,
bon consumption for styrene board is estimated to be less than 0.5 mil--
lion pounds* with emissions probably less than 0*1 million pounds per - :;
year. • •,: r.
IV-40
-------
Roughly 20 million board feet of polyolefin foams were blown in 1975
for packaging, impact cushioning and flotation uses. Chlorofluorocarbons
F-12 and F-ll are most widely used as blowing agents for thin packaging
foams. Dow's ethafoam, made in higher densities and heavier cross sections,
is often foamed with F-114.2ft/ Densities range from 1.5 to 5.0 lb/ft3.
For an average density of 3.5 pcf, total use of chlorofluorocarbon agents
would be less than 0.6 million pounds for 1975.
Thus these three 'types of plastic foams together represent possibly
15% of the chlorofluorocarbon agent emissions from foams. No vapor re-
covery methods are now used. Polystyrene film and sheet extruded from
crystal resin is the only type of operation that might lend itself to
vapor collection and control. However, there is currently no information
on which to predict either the technical feasibility of recovery, or the
potential costs involved.
CONTROL SYSTEMS FOR CHLOROFLUOROCARBON EMISSIONS
The basic technology available for control of solvent vapor emis-
sions to the air, and the design of equipment to achieve the desired re-
ductions in emissions have been described in detail.24-27/ Only those
features of chlorofluorocarbon vapor control which influence either the
performance or the cost of emission control systems will be considered.
Among the emission control systems that have been proposed for re-
ducing chlorofluorocarbon emissions in plastic foam production are:
* Adsorption with solvent recovery,
* Incineration (with heat recovery),
(a) Direct flame pyrolysis,
(b) Catalytic incineration,
* Absorption (scrubbing) with recovery, and
* Vapor condensation and recovery.
Systems Not Applicable for Blowing Agent Vapors
Preliminary analysis indicates that neither refrigeration condensa-
tion, nor absorption by scrubbing are technically feasible for recovering
relatively low concentrations of chlorofluorocarbon vapors from high vol-
ume air streams. The rationale for dropping these approaches from further
consideration are summarized briefly.
IV-41
-------
Vapor Condensation - Use of refrigeration for direct condensation of sol-
vent vapors from exhaust air streams has been proposed, and even tested
on a limited basis as a means of recovering solvents* To date, no suc-
cessful operations have been reported*
Any component of a vapor mixture can be condensed if brought to
equilibrium at a low enough temperature* The temperature necessary to
achieve a given solvent vapor concentration is dependent on the vapor
pressures of the compounds*
When cooling a two-component vapor where one component can be con-
sidered noncondensible, for example, a solvent-air mixture, condensation
will begin when a temperature is reached such that the vapor pressure
of the volatile component is equal to its partial pressure* As the vapor
is cooled further, condensation continues such that the partial pressure
stays equal to the vapor pressure* The more volatile a compound, i.e.,
the lower the normal boiling point, the higher will be the amount that
can remain vapor at a given temperature. The higher the concentration
of a component in the vapor, the greater the percent condensed will be
at a given temperature*
Concentrations of chlorofluorocarbon vapors in exhaust air from most
foam production plants may occasionally reach 2,000 ppm or higher; concen-
trations of 200 to 500 ppm are more common*
To condense 90% of F-ll from'an air stream containing initially
2,000 ppm F-ll, a temperature well below -120°F (-84.5°C) (partial pres-
sure of 0*00735 psi) is required.^*/ The usual thexmophysical property
tables seldom offer values below this range*
At these temperatures, ice formation reduces condenser effectiveness
rapidly, and the problem of removing the condensed mist of solvent drop-
lets from the moving air stream is difficult* The cost of refrigeration
equipment and excessive energy consumption (even with the most effici-
ent exchangers for recovery), prohibit any practical application of di-
rect condensation as a means of recovering chlorofluorocarbons from dilute.
air streams of high volumetric flow rates* .: .-.•_• ....
Absorption - Liquid absorption is a well-known process for removing con-: -
taminants from air streams* This process typically employs a packed col-:r
umn to provide contact between the absorbing fluid and the gas stream* ;-.
It has been proposed that chlorof luoro carbon vapors could be scrubbed _-.r.
out of exhaust air using mineral oil as the absorbent. Because the chloro-
fluorocarbon vapor is relatively dilute in the exhaust air, large.size
columns would be required* A limiting condition usually is the quantity
of absorbant vapor exiting with the air from the stripping column*
IV-42
-------
For petroleum based oils (100 SSU refined mineral oil) the air stream
from a scrubber at 100°F (38°C) would contain more than 100 ppm of oil
vapor (plus any entrained mist). This would partly alleviate one air pol-
lution problem, only to replace it with another. Additionally, progressive
oxidation of mineral oils would contribute a significant odor problem,
since blown oils and waxes are among the most characteristic and offen-
sive odorous compounds at extremely low concentrations.
Special vacuum distilled and carefully refined oils are available
that have exceedingly low vapor pressures. Alternatively, esters of low
vapor pressure such as di-octyl phthalate and other nonvolatile plasti-
cizers might be used. The high cost of such absorbants (> |15/gal) weighs
against their use in such a large-scale process.
No experimental data have been reported to suggest that liquid ab-
sorption can be successfully used to remove chlorofluorocarbons at low
concentrations from high "volume exhaust air, streams. .
Systems not Economical for Low Concentrations
Host evaluations reported in the 1itpraturg24,26,29,30/ show that
incineration, either direct flame or catalytic combustion, is more costly
than adsorption systems for low vapor concentrations. Even with 607. heat
recovery, the cost of incineration systems does not appear favorable when
compared with recovery systems.
Carbon Adsorption Systems
Activated carbon adsorption has been used commercially for solvent
recovery for many years. If chlorofluorocarbon vapors are to be concen-
trated and recovered from the.relatively lean exhaust air streams typi-
cal from plastic foam production, systems using carbon adsorption must
be considered. The theory, design, and performance of carbon adsorption
systems has been thoroughly covered, 24, 25 / an(j will not be repeated here.
An extensive survey of foam producers, carbon adsorption system pur-
veyors, chlorofluorocarbon manufacturers, and foam equipment firms, has
failed to find a single instance in which a carbon adsorption system (or
any other class of emission controls) has been tried or evaluated for
the collection and recovery of chlorofluorocarbons from plastic foam pro-
duction. Smaller, but basically similar adsorption units have been suc-
cessfully used for the recovery of F-113 solvents used in vapor degreas-
ing. Basic adsorption isotherms for F-ll and F-12 have been determined
(see Figures IV-5 and IV-6), along with practical bed capacity data and
other information required to design both adsorbers and regeneration
IV-43
-------
loa
OOOI
.001
.01 ./
Partial Pnnura, p»ia
Sources Activated Carbon Division, Galgon Corporation
F! i . . i •'!••' i '• • • i
1 i ! : , M ! •, , i i ; i , • !
, igure IV;-5.i FC-11 adsorption on BPL activated carbon
I , , ) . . .',.::• '
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Sources Activated Carbon Division, Galgon Corporation
Figure IV-6. FC-12 adsorption on BPL activated carbon
-------
sections* In short, there is no known reason why carbon adsorption cannot
be successfully applied to recovery of foam blowing chlorofluorocarbons.
A few problems are encountered which may influence performance, mainte-
nance, and initial cost and operating expenses for such systems*
In order of importance, the factors that must be considered in apply-
ing this proven technology to the reclamation of chlorofluorocarbons from
foam production are:
!• Reducing the volume (flow rate) of air to be treated*
2. Pretreatment of the air stream to remove contaminants*
3. Design of an efficient regeneration/condensation unit*
4* Possible corrosion problems due to halogens*
5* Maintaining uniformity and quality of reclaimed chlorofluoro-
carbons,
Reduction of Air Flow - The importance of minimizing the volume of air
in which the chlorofluorocarbon vapors are transported to the adsorption
beds cannot be over emphasized* More than any other factor, the air flow
rate determines the c'apital cost of adsorption systems* Air volume also
strongly influences the quality of performance, ease of automatic control,
and the annual cost of operation* The total economics of recovery is so
sensitive to air flow, that it is difficult to make meaningful compari-
sons against possible alternatives until the practical limits of vapor .
collection trade-offs are reasonably well defined*
Removal of Contaminants - For those foams that utilize the more volatile
isocyanates such as TDI (i.e., chiefly flexible slab and molded urethanes),
up to 1 ppm or more of isocyanate vapor may be found in the air exhaust
from the foam dispensing area. Isocyanate vapors react fairly rapidly : ...
with moisture in the air stream to form particles that can be filtered ; -.
out of the air stream* However, any isocyanate residues reaching an acti- ...
vated sorption bed would be strongly bound, gradually reducing bed ca- r -:
pacity for the chlorofluorocarbons. A small quantity of steam injected-. :
into the collection hood or duct, has been suggested as one means.of-xe-. .
.moving unwanted Isocyanate vapor s*JLi/ Since the efficacy of this approach..-!
is not yet known, it may be necessary to employ water sprays or wetted -.: :
fiber filters to Insure removal of amines, isocyanates, surfactants^ or..:./.
any entrained polyols. If this type of pre-treatment of the air stream :
is required,, the extra cost of the contaminant removal section must" be--^
added to any basic, emission control system. Injection of small quantities:
IV-46
-------
of steam should not appreciably increase costs. If steam addition and
filtration removes the contaminants, the customary filter used to pro-
tect the sorption beds should suffice.
Regeneration of Adsorbent - Low pressure steam regeneration of the ad-
sorbent beds is customary. For recovery of low boiling chlorofluorocarbons,
there are certain special requirements which complicate the design of an
efficient regeneration/condensation cycle.
After steam regeneration, the carbon bed is wet. To maximize the
adsorbent capacity for chlorofluorocarbons, partial drying of the bed
is desirable before switching back from steam regeneration to vapor
recovery. This can be accomplished by passing hot air through the bed
for a few minutes, or by using chilled heat exchanger coils ahead of the
beds to reduce humidity in the vapor passed through the carbon beds. This
feature can be omitted, but the bed capacity will be adversely affected.
It is customary to pass dry air through the steamed out carbon for 15 to
20 min after regeneration. An alternative procedure is to regenerate the
beds using heated air rather than steam.
There is little or no problem in condensing and recovering F-ll va-
por (boiling point 75°F or 24°C) displaced during steam or air regenera-
tion. If recovery of F-12 is required, a two-stage condenser section may
be needed* Water vapor and F-ll would be condensed at 33 to 40°F (2 to
5°C), and the F-12 (boiling point 23°F or -0.5*C) condenser would operate
over the range of +30° to -20°F~(-0.1 to -29°C). For foams utilizing only
minor quantities of F-12, it may be too expensive to attempt recovery of
the low boiling chlorofluorocarbon.
Corrosion and Materials - The chlorofluorocarbons do not hydrolyze easily,
and potential corrosion problems are less severe than are regularly en-
countered in vapor recovery systems used for ordinary chlorinated hydro-
carbons. Galvanized steel, aluminum and other reactive metals are not
satisfactory for ducts and hoods. The common plastic or reinforced plastic
ventilation and fume ductwork is preferred. Adsorbent tanks can be made
of phenolic lined carbon steel, or nickel base alloys such as monel. Low
alloy stainless steels of the 300 series are, however, not satisfactory.^'
Quality and Uniformity of Recovered Solvent - For a single chlorofluoro-
carbon, such as F-ll, no difficulties are anticipated in recovery; however,
it is customary to decant the solvent through a drying filter to remove
the trace of dissolved water remaining.
If methylene chloride, etc., is employed as a cleanup solvent, its
vapors may be recovered along with the chlorofluorocarbon. Providing that
IV-47
-------
the proportion of methylene chloride is less than about 5 to 107., there
should be no problem in reuse of the solvents as blowing agents for flex-
ible foams.22/ If the quantity of wash solvent is sufficient to cause
problems in foaming, it may be necessary to close the recovery system
during flushing and cleanup*
In^certain cases where methylene chj.orj.de_andLj^ll are used together,
a significant amount of the more soluble methylene chloride is lost into
the water phase of the condenser tank. This change of proportion may be
sufficient to require that the recovered solvent be analyzed and brought
back to the specified mixture before reuse.
Feasibility of Chlorofluorocafbori Recovery - The technology of activated
carbon adsorption appears to be suited for the recovery of chlorofluoro-
carbon vapors from foam production. In the absence of any reported at-
tempt to apply solvent recovery to commercial foam processes, the prac-
ticality of collecting and recovering chlorofluorocarbon emissions from
the model plants previously defined was considered.
The engineering limitations of greatest importance are:
1. The effectiveness with which chlorofluorocarbon emissions from
foam can be picked up by hoods, enclosures and ventilating systems that
could be provided at- various stages of processing.
2. The lowest air flow rate that will provide both effective chloro-
fluorocarbon vapor collection, and maintain safe levels of toxic vapors
in the workspace near the foam equipment.
3. The concentration levels of blowing agent in the exhaust air
resulting from considerations (1) and (2) above.
For each stage of foam manufacture as specified for the model plants,
the volumes of chlorofluorocarbon vapors, and the typical ventilation
rates were used to compute the concentrations that would result if all
of the vapors were directed into the air exhaust. This assumption can
then be relaxed to approximate the best attainable commercial practice.
Table IV-13 presents values for both the quantities of chlorofluorocarbon
to be recovered, and the maximum concentrations in parts per million for -
five types of foam processes. Obviously, the indicated concentration.levels
would increase if the chlorofluorocarbon vapors could be collected, using;!..,
smaller blowers.
IV-48
-------
Table IV-13. MAXIMUM AMOUNTS AND CONCENTRATIONS OF CBLOROFLDOBOCARBON
(Based upon model plant conditions).*/
Source of cbloro-
Foam process fluorocarbon (FC)
A. Flexible slab
B. Molded parts
C. Rigid boardstock
-
D. Structural foam
pane la
E. Cavity- foam-
in-place
Foam tunnel
Conveyor
Cut-off take-
out
AstinR room
Total
Pour mold
Rise and cure
Demoldlng
Postcure
Crush, flex
Foam tunnel
Trim and slab
saw
rom ««viivf~3j~iu*>
Foam fill
station
Ib FC/
nrirt
18.0
7.2
3.6
6.5
36.0
0.156
0.078
0.390
0.624
0.234
7.78
2.78
0.60
0.39
cu ft FC/
mint/
53.4
21.4
10.7
19.3
107.0
0.464
0.232
1.159
1.855
0.696
23.12
8.26
1.78
1.16
Air
(cfm)
20,000
10,000
15,000
20.000
65,000
10,000
None
5,000
5,000
None
5,000
dust only
5,000
10,000
FC cone.
(ppm)
2,672
2.140
714
963
avg 1,647
46
.
232
371
-
4,625
(1,652
for
5,000 cfm)
357
116
a_/ No values given for on-site foaming; ventilation systems not employed.*
b/ Volume of vapors at 100'F, temperature of air ducts.
IV-49
-------
The values shown in Table IV-13 suggest several observations. The
quantity of blowing agent vapors available for recovery is by far greater
in a flexible foam slab plant than any other type of process. While the
amounts of chlorofluorocarbons are smaller, the potential for vapor re-
covery from continuous rigid boardstock is also fairly attractive* For
flexible molded parts, foam core panels and foam-in-place cavity filling,
the prospects for vapor recovery are not as attractive. It might, how-
ever, be desirable to consider attempting recovery of vapors released on
sawing and trimming rigid stock* The concentration of chlorofluorocarbon
vapors, for both flexible and rigid foam machines, lies in a range highly
suitable for activated carbon adsorption as a means of recovery* If it
were possible to collect a substantial fraction of the chlorofluorocarbon
vapors in a smaller stream of air, the costs of recovery would be reduced
significantly*
The concentrations and quantities of vapors shown in Table IV-13
are for total collection* At present, of course, much less than all of
the vapors are collected along with toxic materials. Even given the best
possible enclosures and ventilation systems, it is optimistic to expect
collection of more than 70 to 80% of the vapors from any particular stage
of processing* The challenge will be to achieve adequate collection with
the lowest practical air flow rates* While some improvements can doubt-
less be made, the extent to which more efficient collection systems can
be developed is not known at the present time*
Given proper engineering of chlorofluorocarbon vapor collection sys-
tems of satisfactory performance, how much solvent could be recovered?
If recovery systems were applied primarily to the more obvious sources
of emissions, by how much could total emissions be reduced? These ques-
tions will be explored using the figures developed in Table IV-13.
It seems conservative to assume that improved hoods and enclosures
(perhaps using ducts drawing from below the foam levels), could achieve
minimum levels of collection as follows:
Flexible slabs
Foam tunnel 75 to 85%
Conveyors 60 to 75%
Cut-off, take-out 60 to 75%
Aging room 50 to 65%
IV-50
-------
Molded flexible
Mold charge 60 to 75%
Post-cure, crush 70 to 807.
Rigid boardstock
Foam tunnel 70 to 80%
Trim and slab saw 50 to 65%
. Structural foam core panels
Foam tunnel 60 to 75%
Foam-in-place cavity filling
Fill station 70 to 85%
Modern carbon adsorption vapor recovery systems are capable of re-
covering 93 to 98% of all chlorofluorocarbons entering the sorption beds.
If the preceding schedule of fractional vapor collection was treated at
an average recovery of 95%, the results would be those shown in Table
IV-14.
Recovery of chlorofluorocarbons for re-use in foaming may provide
attractive cost savings for flexible bun and molded foam producers. From
50 to 70% of the total chlorofluorocarbon requirements might be met by
efficient vapor recovery. Recovered blowing agent as a fraction of total
consumption is much smaller for all the rigid urethanes. It is unlikely
that cost savings alone would induce concern for chlorofluorocarbon emis-
sion controls for most rigid foam production.
Economic Evaluation of Chlorofluorocarbon Recovery - Given the present
uncertainty relating to chlorofluorocarbon emission rates, and the levels
of vapor collection that could be achieved in practice, only a crude and
preliminary treatment of expected system costs and potential savings from
recovery is warranted.
To indicate the possible range of costs and savings that might be
expected, two situations were examined:
1. Recovery of chlorofluorocarbon vapors from the primary foam sec-
tion of a flexible slab machine.
IV-51
-------
Tablt IV-14. POTENTIAL OOHTBOL OF CHLOBOFUJOBOCAKBDN EMISSIONS FROM FOAMS
J ' ! t ; •< •
Foam proceac and stage
i
A. Flexible urethsne slabs took
Foam tunnel
Conveyors
Cut-off, take out
Aging room
Total plant emissions^
B. Molded flexible parts
Molded charge
'. Postcure, crush
: . Total plant emissions^/
H
1 X
}3 . C. Rigid boards tock
' Foam section
< Trim, slab saw
Total plant emissions^'
D. Structural foam panels
Foam section
Total plant emissions*/
B. Foam-tn-place cavltr till
Filling station
Total plant emissions-'
i • i
i
Annual
emissions (Ib) % Treated
421,200 85
168,480 75
84,240 75
151.632 65_
846.612
25,833 75
94.724 80
183,418
216,000 80
60.480 65
291.600
••
51.840 75
55.987
.
46.919 85
50,276
Annual
recovery (95%)
340.119
120.042
60.021
93.633
613.815
18J406
71.990
90.396
164.160
37.346
201,506
36.936
36.936
37.887
37,887
Percent
emission
reduction
80.8
71.3
71.3
61.6
72.5
71.3
76.0
49.3
76.0
61.8
69.1
71.3
66.0
60.1
75.4
$ Recovered FC;
X of consumption
$245,526
72.5%
$36,155
49.31
$80,602
14.81
$14.775
8.8%
$15.155
13.4%
ml Total plant emissions Include all handling and other chlorofluorocarbon (FC) loaaea, plus FC retained In flexible Coi
-------
2. Recovery of chlorofluorocarbon vapors from the post-cure and
crush stage of molded flexible foam parts*
The first recovery system will be custom designed and built to handle
relatively large quantities of chlorofluorocarbon in a stream of 20,000
cfm. An equipment allowance of 10% is included to steam remove undesirable
isocyanates before entering the carbon beds.
The requirements for the second system are sufficiently small that
a pre-packaged, fully automatic solvent recovery system may be chosen*
For lower air flow rates* these units do not require attention by an
operator, and only regularly scheduled maintenance is typical*
The conventions used in estimating costs and savings are the same
for each system, and generous allowances for escalation of equipment
costs were included as a hedge against uncertainty:
Equipment life = 15 years*
Interest (discount) rate = 10%,
Capital recovery factor = 0*13147.
Carbon replacement in year 8,
•
Chlorofluorocarbon price 36$/lb; 40,000 Ib tank truck, FOB delivered,*
Package unit price from VIC Manufacturing Company as of December 1975,
and
Custom system price, highest estimate obtained***
* F-ll price quoted by E. I* du Pont, Freon Division, per Kevin Coile.
** Prices suggested for carbon adsorption systems ranged from $7 to $15/
scfm of air stream. Prices of $7.00, $7.50, $8.00 to $10,00 and
$10.00/scfm were for equipment only* Prices of $11*50 (large size)
and $15.00 (smaller units) per scfm were for complete turnkey in-
stallations and included all controls, and an engineering fee of
$4.50/scfm. Price estimates were furnished by: Hoyt Manufacturing
Company, Sutcliffe-Speakman Limited, Vulcan-Cincinnati, Calgon
Corporation, VIC Manufacturing Company, and Strauss Systems, Inc.
IV-53 "
-------
Table IV-15 shows the calculation of annual costs and savings for
primary foam section of the flexible foam machine. Given effective (85%)
collection of the chlorofluorocarbon vapors, the annual savings from F-11
recovery considerably exceed.the annualized costs* This would remain the
case, even if less than 50% of the F-ll vapors were collected for recovery.
The economics of recovering the vapors diffusing from molded parts
during post-cure and roll crushing are somewhat less favorable* Table
IV-16 shows that recovery of nearly 72.000 Ib of chlorofluorocarbon yearly
will return the capital investment in about 2.5 years. The ratio of an-
nual savings to annualized costs would remain above the break-even point
at any vapor collection level above 55%.
The economic projections used are admittedly qualitative and based
upon uncertain technical factors. It does appear, however, that collection
and recovery of chlorofluorocarbons may be economically feasible for those
locations where substantial quantities of vapors can be collected. The
actual determination of these locations is essential to further considera-
tion. Analytical studies are needed, together with investigations of the
performance of modified ventilation systems.
. IV-54
-------
Table IV -15. CALCULATED SAVINGS/COST RATIO FOR GHLOROFLUOROCARBON RECOVERY
Basis: Foam tunnel of flexible ur ethane slab 'model plant
Air flow rate 20,000 scfm
Chlorofluorocarbon vapors 36.0 Ib/min; 842,400 Ib/year
Fraction collected 0.85 - 30.6 Ib/min
C^lorpfJLuoro carbon i.recovery_. 95%; 680,238 Ib/year
A. Value of recovered F-ll at 36£/lb |244,886/year
B. Exhaust concentration
30.6 Ib/min x ^ ft3/mol x 559^ = 90<84 ft3 F.u at 100<>F
137.4 Ib/mol 492 °R
90.84 ft3
4,542 ppm & 0.067 psia
20,000 cfm
Bed capacity at 100°F, 0.067 psia » 16.07. by wt. F-ll
C. Plant investment required—'
Complete c~arTx>h adsorption system witn controls $230,000
at $11.50/cfm including engineering design.
Pretreatment of vapors, add 107. $23,000
r
Installation costs at 157. $27.600
$370,600
Carbon replacement after 8 years ($150,000)
Present value of deferred investment at $64,570
107.
Total capital investment $345,170
IV-55
-------
Table IV-15 (Concluded)
D. Annual operating cost&fl/
1 operator, 65 days $6»0()0
Steam at 3.5 Ib/lb F-ll $6,720
Cooling water and refrigeration $3,200
Maintenance at 57. $18,500
Insurance at 27. $7.400
$41,820/year
E. Equipment depreciation 15 years
Discount rate 10%
Capital recovery factor 0.13147 to recover investment and 10%
interest over the 15-year life of equipment.
F. Annual capital cost ' $45,380
Annual operating costs $41,820
:$87,200~
Savings/cost ratio - $244,886 . 2-8Q
$ 87,200 ;
£/ Ventilation ducts and 30-hp fan not included, assuming an equivalent
20,000 scfm system already installed and in regular use.
IV-56
-------
Table IV.-16... CALCULATED SAVINGS/COST RATIO FOR MOLDED FOAM PARTS
Basis: Post cure and flex section of model plant
Air flow rate 5,000 cfm
F-ll vapors 412 Ib/day; 858 Ib/min
Fraction collected 0.80; 0.686 Ib/min
F-ll recovery 9578; 71,990 Ib/year
A. Value of recovered F-ll at 36
-------
Table IV-16^ (Concluded)
E. Equipment depreciation 15 years
Discount rate, 10%
Capital recovery factor 0.13147 to recover investment and 10% interest
over the 15-year life.
F. Annual capital cost $8,755
Annual operating costs $6.562
$15,317
Savings/cost ratio -
915,
IV -58
-------
REFERENCES
1, Modern Plastics, Annual Statistical Summary, January 1976*
2. Mobay Chemical Corporation, "Urethane Market Report 1975," June
1976.
3. Buist, J. M., "Advances in Polyurethane Technology," John Wiley,
New York (1968).
4. "Plastics Technology," p. 9, October 1974.
5. "Maxfoam - New System for Foam Slabstock," Unifoam A. G., Glarus,
Switzerland.
6. Allied Chemical Corporation, National Aniline Research Notes RN-8,
"Flexible Urethane Foam Self Extinguishing Properties" (1961).,
7. Mobay Chemical Company, Technical Information Bulletin 35-F-12.
8. Frisch, K. C., and J. H. Saunders, Plastic Foams, Dekker, New York,
p. 72 (1972).
9. Personal communication, John Crossley, Grain Industries, Ft. Smith,
Arkansas.
10. Ward, R. B., "The Safety of Fluorocarbon Blowing Agents for Poly-
urethane Foams," E. I. du Pont de Nemours and Company, Inc. (1975),
11. Personal, communication, Dr. John Backus, Mobay Chemical Corporation,
Pittsburg, Pennsylvania.
12. Frisch, K. C., and J. H. Saunders, Plastic Foams, Dekker, New York
(1972).
IV-59
-------
13, Personal communication: J. H. Martin, Ford Motor Company, Utica,
Michigan; and W. Karnes, Martin Sweets Company, Louisville,
Kentucky.
14. Johnson, V,, "Specifying Urethane Foam Machinery," Plast. Technol.,
pp. 104-190, mid-April 1975.
15. Personal communications: John Curtis, Polymer Chemicals Division,
Upjohn Company; Dick Hayes, CPR Division, Upjohn Company; and
Dr. M. E. Kapplan, Allied Chemicals.
16. Nadeau, H. G., et al., "A Method for Determination of the Cellular
Gas Content of Rigid Urethane Foams and Its Relationship to Ther-
moconductivity," Journal of Cellular Plastics, Proceedings of Con-
ference, Natick, Massachusetts, April 13-15, 1966, HAS/NRG,
Washington, D.C. (1967).
17. Becker, W. £., "U.S. Sandwich Panel - Manufacturing/Marketing Guide/1
Technomic Publishing Company (1968).
18. Kuryla, W» C., et al., "The Mold Pressure Characteristics of Rigid
Urethane Foams," Journal of Cellular Plastics, pp. 532-537,
December 1967.
'19. Personal communications: Mr. Ray Clausen, President of UFCA and
President, Great Lakes Systems, Inc.; Mr. Jeffry Scott, Ransburg
Corporation.
20. Personal communications: Leonard Martin, Martin Panels, Inc.,
Kansas City, Missouri; R. Clausen, Great Lakes Systems, Inc.,
Grand Rapids, Michigan.
21. Personal communications: D. Shreeve, Binks Manufacturing Company,
Chicago, Illinois; D. Jackson, Ransburg, Indianapolis, Indiana.
22. Steinle, H., "On the Behavior of Polyurethane Foams in Refrigerator
Cabinets," IIR Proceedings. Washington, D.C. (1971); F. J. Norton,
"Thermal Conductivity and Life of Polymer Foams," Journal of
Cellular Plastics, pp. 23-27, January 1967.
23. Arthur D. Little, Inc., "Preliminary Economic Impact Assessment of
... Possible Regulatory Action to Control Atmospheric Emissions of
Selected Halocarbons," EPA Contract No. 68-02-1349, Task 8, Pub-
lication No. EPA-450/3-75-073, September 1975; NTIS No. PB-247-
115.
IV-60
-------
24. Environmental Protection Agency, "Air Pollution Engineering Manual,"
Second Edition, Hay 1973, pp. 171-229.
*
25. Environmental Protection Agency, "Package Sorption Device System
Study," Mine Safety Appliance Company, PB-221-138, EPA Publica-
tion No. R2-73-202, April 1973.
26. Rolke, R. W., et al., "Afterburner Systems Study," Shell Develop-
ment Company, EPA Publication No. R2-72-062, August 1972.
27. "Control Technology for Hydrocarbons and Organic Solvent Emissions
from Stationary Sources," NAPCA Publication No. AP-68, March 1970.
28. ASHRAE Guide and Data Handbook, American Society of Heating, Refrig-
eration and Air-Condition Engineers, Inc., Joseph D. Pierce, Chair-
man, New York (1972).
29. Lovett, W., "Control of Industrial Process Odors," Calgon Corpora-
tion (1975).
30. Dow Chemical Company, "Study to Support New Source Performance Stan-
dards for Solvent Metal Cleaning Operations," Final Report, EPA
Contract No. 68-02-1329, Task 9, June 1976.
31. Personal communications: W. Crydexman, Accuratio Systems, Louisville,
Kentucky; T. Haggerty, Rubicon Chemical Division, Unirpyal Corpora-
tion, Naugatuck, Connecticut.
32. Larson, D. M., "Control of Organic Solvent Emissions by Activated
Carbon," Metal Finishing. December 1973.
33. 'ttethylene Chloride, Urethane Grade: Blowing Agent, Solvent, Pre-
polymer Thinner," Dow Chemical Company (1974); "Methylene Chloride
and Refrigerant-11 as Urethane Foam Blowing Agents," Mobay Techni-
cal Bulletin 75-F-29 (1964).
34. Telephone discussion with Mr. John M. Kennedy, Technical Manager,
Dow Chemical Company, Ironton, Ohio.
IV-61
-------
SECTION V
CLEANING AND DRYING SOLVENTS
This chapter discusses the sources of solvent emissions and possible
methods for the control and/or recovery of emissions from the use of chloro-
fluorocarbons (primarily F-113) as cleaning and drying solvents.
Data in numerous reports and trade publications show clearly that
the total consumption of chlorofluorocarbons as cleaning and drying sol-
vents is relatively minor, both with respect to the overall consumption
of these compounds and to the total quantity of solvents utilized for
this, application,. 1-3/ Solvent consumption accounts for approximately 5
to 9% of the total chlorofluorocarbon production according to different
sources. The use of F-113 (and very small quantities of F-112) accounts
for only about 5% of the total solvent consumption* The chlorinated hy-
drocarbons (e.g., trichloroethylene, methyl chloroform, etc.) are the
dominant factors in this area*,!/ F-113 and its azeotropes do not compete
with the chlorinated hydrocarbons as general purpose solvents with in-
dustry-wide applications..!/ Because of its relatively high cost, F-113
is utilized primarily only in those applications where either a high
level of cleaning quality is required or alternative solvents may pose
a problem of compatibility with the materials of construction.
Chlorofluorocarbon solvents have basically five applications:
(1) defluxing and electronics cleaning; (2) specialized degreasing;
(3) displacement drying; (4) dry cleaning; and (5) miscellaneous spe-
cialty applications* Of these five areas, the first two represent, by
far, the major sources of chlorofluorocarbon consumption in terms of
total quantity* Specifically, the two major uses for F-113 based sol-
vents are the defluxing of printed circuits and the general cleaning of
components for the electronics industry. These solvents are well suited
for this application because of their ability to remove the flux used
in high-volume production of machine-soldered boards while, at the same
time, displaying compatibility with the materials of construction. These
solvents are also well suited for flux removal after hand-soldering
V-l
-------
operations associated with printed circuit rework and repair. Within the
electronics industry and the military, large quantities of F-113 based
solvents are used for the cleaning of printed circuits and electronic
components intended for military use; as such, the solvent systems may
have to conform to military specifications*
Dow Chemical Company recently made a study for EPA of the vapor-
degreasing* area with respect to these same factors of emissions, their
control, efficiency, and costJt/ Their comprehensive report, however,
was directed primarily at the chlorinated hydrocarbons. Through discus-
sions with a major chlorofluorocarbon producer, manufacturers of vapor-
degreasing equipment, and a manufacturer of vapor-recovery systems, it
was determined that a considerable portion of the data developed for
chlorinated hydrocarbons was equally applicable to F-113. Because of dif-
ferences in the physical properties and the types of solvent systems
(azeotropes), control of F-113 does require certain differences from that
for chlorinated hydrocarbons. These differences are considered as part
of the discussion of the appropriate recovery and/or reduction method.
However, the discussions and data in the report by Dow Chemical Company
have been incorporated, to a considerable extent, in the material pre-
sented in this section. A similar study has recently been completed by
the Energy Systems Group of TEW, Inc., in which the sources of emission,
solvent recovery and/or reduction methods, efficiency of methods, and
cost parameters were evaluated for the dry cleaning industry^/ In the '
TEW report, as in the Dow report, F-113 was not the primary solvent of
interest because of the low volume consumed compared with the other sol-
vents. However, the data and evaluations for F-113 were comprehensive
and, thus, the discussion of the dry-cleaning industry, presented later
in this section,! incorporates a considerable portion of the evaluation
presented in the report by TRW, Inc.
In the subsequent subsections of this section, each of the areas
of room-temperature cleaning (commonly referred to as cold cleanings),
vapor-degreasing, and dry cleaning will be discussed with respect to
sources of solvent emissions, methods of emission reduction and/or re-
covery, efficiency of the methods, and cost factors related to the
methods.
Hereafter in this section, the term vapor-degreasing will be used,
but it is to be understood that this term includes both cleaning
and degreasing operations.
V-2
-------
GOLD GLEANING
According to the Dow report, there are 1,026 plants in the United
States that employ the use of F-113 or its azeotropes in cold-cleaning
processes^/ This figure represents about 7% of the estimated 14,955
plants that employ some type of cold-cleaning operation* The total quan-
tity of F-113 consumed in the 1,026 plants was estimated at 19.5 x 106
Ib or an average of about 19,000 lb/plant^/ According to a major pro-
ducer of chlorofluorocarbons, approximately 80% of the annual consumption
of F-113 solvent in cold-cleaning equipment is for replacement of used
solvent in existing equipment, and 20% is used to fill new equipment..6/
Cold cleaning procedures represent the simplest mechanical operations
of the three types of cleaning procedures to be discussed in this section.
These operations generally include the processes of wiping, spraying
(flushing), immersion (dipping), and solvent wasb.ers.Za2/ For F-113 sys-
tems, very little solvent is used for wiping parts, because the lower
cost solvents are much more advantageous. The major F-113 producers have
stated that approximately 90% of the F-113 consumed for cold cleaning
purposes is pure (nonazeotrope) solvent, and the remaining 10% consists
of azeotropic solvent systems.^/ This situation is essentially reversed
for vapor-degreasing systems.
As discussed earlier in this section, the use areas for cold clean-
ing operations can be divided into military and nonmilitary oriented ap-
plications* In addition to its use with printed circuits, F-113 also finds
usage in flushing operations on precision guidance equipment, such as *
gyroscopes, and in white-room cleaning associated with the aerospace pro-
gram. Approximately 85 to 90% of all F-113 consumed in cold cleaning is
estimated to be for military-oriented applications, and 10 to 15% for
general benchtop cleaning purposes.£/ For military applications, partic-
ularly in the case of flushing operations on high-precision equipment,
once the solvent has been used and becomes contaminated, it no longer
meets the military specifications for that solvent and is downgraded.
The downgraded solvent is then used either for other solvent applica-
tions which have less stringent military specifications or for nonmili-
tary applications. An estimated 75% of all F-113 consumed in military
flushing and spraying applications is reused for other operations.^/
Sources of Solvent Loss
The major sources of solvent loss from cold-cleaning operations are
due to: (1) evaporation of the solvent; (2) solvent "dragout" losses
on the cleaned parts; and (3) solvent disposal practices. Evaporation
of solvent refers to volatilization from the liquid surface of the clean-
ing tank as opposed to the intentional discard of used, contaminated or
V-3
-------
excess solvent* Dragout losses refer to those emissions occurring as a
result of solvent being retained in or on the part being cleaned. Parts
withdrawn from cold cleaning systems often remain wet with solvent, or
solvent is trapped in small holes or crevices in the part; this solvent
ultimately evaporates uncontrolled into the atmosphere* The severity of
dragout losses is very highly dependent upon the configuration of the
article being cleaned* In the immersion cleaning of small parts, articles
such as ball bearings would exhibit lower losses than an intricate part
containing numerous small holes or crevices* For an average .situation
in which the part to be immersion-cleaned is neither overly simplified
nor complex, the approximate percentage loss by each of the three major
sources is: dragout, 50%; evaporation, 35%; and disposal, 15%.8.7 For
the cleaning of printed circuits, the dragout losses resulting from im-
mersion cleaning are less severe than with other cleaning operations,
and the percentage loss by each of the three sources has been estimated
to bes evaporation, 40 to 45%; solvent disposal, 35 to 40%; and dragout,
20 to 25%*2/ The rationale for the high solvent disposal percentage from
immersion cleaning of printed circuits and electronic components is that
the manufacturers are producing high-quality low-reject-rate products,
and that the consumption of cleaning solvent is secondary to this need*
A major electronics corporation has provided information on its F-
113 cold-cleaning operations*^?./ This cleaning process is used for metal
components prior to their assembly in cathode ray tubes* These parts are
generally comprised of cathode filaments, electrical contacts, support
wires, grids, vanes for electrostatic guidance of the electron beam, etc*
Since these parts are relatively simple pieces, being either flat or
slightly bent, dragout losses are generally quite low unless the parts
cluster together or the operator fails to allow sufficient drainage time*
Approximately 70% of all of its cleaning operations utilize 5 to 10 gal*
cold-cleaning tanks; the remainder is by vapor-degreasing. These cold-
cleaning tanks are larger than the average type of F-113 cold-cleaning
unit discussed below* For this cold-cleaning operation, solvent losses
have been estimated as: evaporation, 80 to 85%; dragout, 10 to 15%; and
solvent disposal, 5%. Solvent disposal is considerably lower than the
figures stated above, because this company recycles the used solvent by
in-house distillation*
For the cold cleaning of small parts, numerous small cleaning tanks
are generally employed; the most common size of these tanks is 6 in* x
10 in* x 7 in* with a solvent capacity of approximately 1 quart .£/ These
tanks are normally either placed on the workbench or in the immediate
vicinity of the workers. Benchtop cleaning operations are basically un-
controlled, and eventually result in an almost 100% loss of solvent. Be-
cause of the number of these units and their very low volume of solvent
per unit, very little of the used solvent is collected for distillation
V-4
-------
and reuse. Covers are supplied with virtually all cold cleaning units;
however, it is not common practice for the covers to be utilized.^/ Cold-
cleaning units also are typically filled reasonably close (to within 2
in.)" to the top of the tank with solvent. This short distance from the
solvent surface to the top of the tank (termed "freeboard" height) con-
tributes significantly to the evaporation emissions of the solvent. The
normal or "average" operation for small parts is to place the articles
to be cleaned in a screen-wire basket, and to immerse the basket in the
tank. Pumps are sometimes used to create turbulence in the solvent but
more commonly, the baskets are manually raised and lowered to accelerate
the cleaning action. Ultrasonic units are often used to assist in the
cleaning action. The use of ultrasonics increases the evaporation rate
of the cleaning solvent considerably. After a specified period of time,
the baskets are removed, drained momentarily, and placed on the workbench.
For flushing operations, the situation is approximately the same
as for immersion cleaning. If the article to be cleaned has numerous
closely-spaced components, solvent will be trapped within these areas
and eventually emitted into the atmosphere unless a proper drainage time
is allowed. Very often, the drainage period is minimal, at best.
Conveyorized cold-cleaning equipment is used by high volume pro-
ducers of machine soldered printed circuits and other electronic com-
ponents, but the total number of such units is small. Excess flux and
soil removal occurs when the articles are sprayed or brushed as they
pass through the washer. The solvent drains to a holding tank and is
recycled through the spray system. Solvent vapors are removed through
the ventilation exhaust systenu^Liii/ Losses of solvent also occur by drag-
out and by evaporation through the entrance and exit areas of the con-
veyor .i!/
Cleaning procedures which utilize F-113 in small volume aerosol or
manual spray containers result in direct uncontrolled emissions into the
atmosphere.
Although solvent losses do occur, solvent producers and equipment
manufacturers generally say that users of F-113 solvent systems are
more conservative in their operating practices than users of other sol-
vents, primarily because of the nature of the business (precision elec-
tronic equipment, military applications, etc.) and the high cost of the
F-113 solvent. This does not necessarily Imply that good "housekeeping"
practices are always employed by users of F-113 solvent systems.
V-5
-------
Potential Emission Contro1 Techniques
The potential emission control techniques discussed herein are basi-
cally those presented in the report by Dow Chemical Company but, in many
cases, have been supplemented with data from additional sources. Careful
attention to good "housekeeping" practices, while not a specific emission
control, can certainly serve to reduce uncontrolled emissions and thereby
assist the emission controls in reducing solvent loss*
Covers - Covers are supplied for essentially all cold-cleaning systems
and should be employed to help reduce evaporative losses, particularly
during nonshift periods, holidays, and weekends*^/ For any tank used in
an irregular time sequence, covers should be employed if periods of non-
use exceed a half hour in length* Cold cleaning tanks are used for actual
cleaning operations only about 25% of the work shift time*i/ It has been
estimated that a well-fitted, gasketed cover could, conservatively, re-
duce evaporative emissions by about 60%*§'Since covers are normally sup-
plied with the unit, the only possible additional cost would be for a
gasket seal inside the covers. However, the control of evaporative losses
from cold-cleaning operations may not reduce the total emissions to the
atmosphere significantly unless the control of waste solvent disposal
is also controlled* Many of the current waste disposal methods for used
solvent result in uncontrolled emissions to the atmosphere.
Drainage - Since solvent dragout losses represent the largest solvent
loss mechanism, proper drainage is essential. For spraying operations,
a*coarse spray pattern should be employed and troughs provided to col-
lect the overspray and drainage. A drainage area should be designated
and utilized to provide an opportunity for the solvent to drain from the
parts. Whenever possible, the parts should be rotated to assist in the
drainage. These factors are equally applicable to flushing operations
in which solvent entrapment can occur resulting in dragout losses.
For small parts cleaning involving the use of the small benchtop
immersion tanks, rotation or shaking, if possible without incurring
damage to the parts, should be employed to reduce solvent entrapment.
Additional methods can be employed to help reduce dragout losses. The
mesh of the wire screen of the basket could be changed, in some cases,
and thus reduce the quantity of solvent being entrapped by the basket
itself, although for very small parts, a fine wire screen is necessary.
A simple addition to the current basket design could also be employed
to help reduce dragout losses.^/ A hook device of some type could be
attached to the basket to allow the basket to be hung on the end or
side of the immersion tanks, and thus allow excess solvent to drain
back into the tank. These devices are currently standard items on some
V-6
-------
types of unitsj*/ If such devices are not present, they could be added
to existing units for a cost probably not exceeding $3 to $4j*/ Based
on a current cost of about $50 to $75 for a 6 in. x 10 in. x 7 in. unit
without ultrasonics and a cost of about $200 for a unit with ultrasonics,
the added cost of $3 to $4 is quite nominal. If the basket was to re-
main in this position as each piece is removed, as needed, dragout losses
could be substantially reduced. While exact figures for the reduction
in dragout losses are not available and would be highly dependent upon
the configuration of the part, a reduction of 50% or more may be possible
in many uses.
Waste Solvent Recovery - Most cold cleaning operations seldom result in
a contamination of the used solvent to a level greater than 10% by vol-
ume; this results in a used solvent which generally is 90% recoverable.^/
Simple distillation equipment can be used for F-113 solvents, because
of its nonflammability. More expensive explosion-proof systems are avail-
able for flammable solvents. When the use of stills is considered for
recovery of F-113, the type of soil (contaminant) and the initial or re-
quired purity or grade of the F-113 must also be considered. If the ini-
tial solvent was PGA (precision cleaning agent) grade F-113 and the soil
was a very light weight oil, numerous (up to 30) distillations may be
required to return the distillate to its original purity. On the other
hand, if the original purity of the F-113 was not critical and the con-
taminates were heavy oils, a single distillation may provide an accept-
able product.J^/ Cold-cleaning, operations are seldom equipped with dis-
tillation equipment except in the case of large conveyorized F-113
operations.
•
The economics of the in-house distillation of F-113 is based solely
on the quantity of solvent which can be recovered for reuse. For these
calculations, it is assumed that PGA grade F-113 is not required, and
that a single distillation would provide a solvent of adequate purity.
Adequate 60 gal/hr, water-cooled stills are available in the price range
of approximately $3,000 to $4,000 or an average of about $3,500,1ft/ The
same;size still equipped with direct expansion refrigeration (5 h.p. air-
cooled motor) would cost $6,700.J^4/ The following parameters have been
used in this calculation:^*^/
* An average still cost of $3,500
* Fifteen years still lifetime
* Fifteen percent of capital for installation cost
* Direct floor space of 3 ft x 4 ft
V-7
-------
* Indirect floor space equal to 50% of direct (i.e., 6 ft2)
* Building capital cost of $25.9/ft2
* Twenty-five years building life
* Insurance costs equal to 2% of equipment cost
* Maintenance costs equal to 4% of equipment cost
* Ten percent time value of money for annual costs
Using these parameters, the annual cost of a 60-gal/hr electrically heated,
water-cooled still can be calculated as foliowasZ/
Capital equipments $3,500
Installation cost: 525
$4,025
Annual cost: $4,025 x 0.13147* $529
Building capital: IS ft2 x $25.9/ft2 = $466
Annual building capital cost: $466 x 0.11017** 51
Insurance ($3,500 x 0.02) . 70
Maintenance ($3,500 x 0.04) 140
Total annual cost $790
If an operating cost of $0.20/gal is assumed, then, based on an F-113
value of $6.60/gal,*** the value of the recovered solvent after opera-
ting costs is $6.40/gal. Thus, the total annual cost of this type of
installation could be recovered by the collection of 124 gal. of solvent.
This quantity could be recovered in slightly more than 2 hr of continu-
ous still operation.
* The factor for returning principle plus 10% interest over a 15-year
time period is 0.13147.
** The factor for returning principle plus 10% interest over a 25-year
time period is 0.11017.
*** Price from Chemical Marketing Reporter ($0.50/lb and 13.2 Ib/gal),
June 21, 1976.
V-8
-------
Freeboard Height - Because of its potentially greater significance, a
more detailed discussion of freeboard height and of its influence on
evaporation rates is presented later in the subsection concerned with
vapor degreasing. Host cold cleaning tanks have shallow freeboards, i.e.,
short distances from the solvent surface to the top of the tank. While
this distance depends upon the size or volume displacement of the part
to be cleaned, most users normally fill the tank to within about 2 in.
of the topJL/ At this level, evaporative losses could be substantial,
especially if air drafts are present. Data on solvent loss as a function
of the freeboard height to tank width ratio is shown below in Figure V-
1 for a F-113 system under static conditions at a room temperature of
72°F (22°C). These conditions represent typical solvent losses from a
cold-cleaning unit while it is not in an operating cycle, i.e., no work
is being cleaned. From the curve, it can be seen that as a freeboard
height to width ratio of 1.0 is approached, the increments of solvent
loss become smaller and that beyond a ratio of 1.0, very little de-
crease in solvent loss occurs.
d.7|p-
'0.6
0.5
0.4
0.3
0.2
0.1
Static Losses @ 72°F
I
I
I
I
I
I
I
I
I
0 ! 0.1 0.2 0.3 0.4 0.5 0.6 0.7 ,0,8 :0.9 1.0 11.1 ; 1.2
Freeboard Height/Width Ratio
Figure V-l. Solvent loss as a function of freeboard
height/tank width ratio
Using a 6-in. wide tank as a model and assuming that the solvent
loss curve for static losses is valid for small width (6 in.) tanks,
it can be calculated that increasing the freeboard height from 2 in. to
V-9
-------
6 in* would result in a decrease in evaporative emissions of approxi-
mately 71%. To produce new tanks with a depth of 11 in. instead of 7 in.
would result in an increased cost of the unit of about 207. or $10 to $15
for a current 6 in* x 10 in. x 7 in. cold cleaning unit costing $50 to
$75*i/
Refrigerated Freeboard Coils - In the course of discussion of refrigerated
freeboard chillers, Dow Chemical stated that the use of a refrigerated
air blanket above a cold-cleaning tank would be expected to reduce the
evaporative losses; but that, because of the intermittent use of most
cold-cleaning operations, the use of a cover could be expected to provide
a more efficient means of controlling the evaporative losses.^/ Since
essentially all cold-cleaning units are equipped with covers, the addi-
tion of refrigerated freeboard chiller would appear to entail unnecessary
expense and nonproductive use of energy and refrigerant.
Solvent Cooling - It is possible that the use of chilled water coils be-
neath the solvent surface could be used as a means to lower the tempera-
ture of the solvent, thereby decreasing its vapor pressure with a sub-
sequent lowering of the evaporative emissions.
From a vapor \pressure-versus-temperature curve, it can be estimated
that decreasing the temperature of F-113 (Freon® IF) from 72°F (22°C)
to 40°F (4°C) would result in a vapor pressure decrease of approximately
53% (6 psia to 2.8 psia)Jtl/ As with refrigerated freeboard coils, the
use of a cover would provide a more effective means for evaporative emis-
sion control without the added expense of solvent cooling coils. Additional
factors would be the possible detrimental effects on the cleaning power
of F-113 resulting from the decrease in solvent temperature, on the drag-
out losses, on the drying time for the cleaned parts, and on moisture
condensation on the parts or the solvent.
VAPOR CLEANING AND DECREASING
According to a published report on organic solvent metal cleaning
operations, 1,014 plants in the United States employ the use of F-113,
or its azeotropes, in vapor cleaning or degreasing operations*?.' This
figure represents about 117. of the estimated 9,292 plants that employ
one or more types of solvent for vapor cleaning and degreasing. The
total quantity of F-113 based solvents consumed in the 1,014 plants was
estimated at 36.6 x 106 Ib, or an average of about 36,150 Ib/pLant.ft/
According to a major manufacturer of chlorofluorocarbons and an equip-
ment manufacturer, approximately 85 to 90% of the annual consumption of
F-113 in vapor degreasing operations is for the replacement of used sol-
vent in existing equipment, and the remaining 10 to 15% is used to fill
V-10
-------
new equipment ..SjJA/ with respect to the type of F-113 based solvents
used in vapor degreasing operations, it has been estimated that approxi-
mately 90% of all F-113 defluxing in the electronics industry employed
the use of azeotropes, and that for metal cleaning, a very large per-
centage of the F-113 used is in the form of the azeotropes.j^./ Based on
this information and comments from other users and equipment manufac-
turers, perhaps 85% or more of all F-113 used in vapor degreasing opera-
tions is in the form of an azeotrope. Pure F-113 is a very mild solvent
so that its usage in this area is somewhat limited. A tabulation of F-
113 azeotropes has been presented in an earlier report^/ but perhaps
three of the more common azeotropes are: 50% F-113 + 50% methylene chlo-
ride; 96% F-113 + 4% denatured ethyl alcohol; and 89% F-113 + 11% acetone.
In very simple terms, vapor degreasing is a largely physical method
of removing soluble and insoluble soils from an essentially nonporous
surface. The soiled article, at room temperature, is brought into con-
tact with hot, nearly saturated, solvent vapor. The vapor condenses on
the article's surface, and the liquid removes soil as it drains by grav-
ity. Vapor degreasers are of two types: open-top machines and conveyorized
units. There are many variations of each of these two types. For the use
of F-113 solvents, approximately 95% of the vapor degreasers are open-
top machines and 5% are conveyorized units.147 The conveyorized units
are used primarily by the large, high-volume electronic components manu-
facturers. Other users employ multiples of the smaller, open-top machines.
Of the open-top machines, the most prevalent units for this solvent
are the medium sized, hand-operated immersion machines containing two
sumps. In terms of actual dimensions, the most common F-113 units are
either 14 in. x 20 in. x 12 in.14./ or 12 in. x 32 in. x 12 in.,&/ with
30 to 35 gal. solvent capacities. A typical two-sump F-113 vapor degreaser
is shown below in Figure V-2.
ComfematcT
/-Vopor Uv*l
Figure V-2. Typical F-113 vapor degreaser
V-ll
-------
From the boiling chamber (sump), heavier-than-air solvent vapors rise
to displace the air in the tank* The height, to which the upper level
of the pure solvent vapors is allowed to rise, is controlled by the con-
denser coils located on the sidewalls of the degreaser tank, these con-
denser coils employ a heat-exchange fluid, normally water, and are designed
so that.they are theoretically capable of condensing all of the solvent
vapor. Condenser coils vary in number and design depending upon the size
of the equipment. A water jacket is also normally included to provide
freeboard cooling and prevent heat,convection up the tank walls. Beneath
the condensing coils, a condensate trough collects liquified solvent va-
por, along with some moisture from the air. This liquified solvent is
passed through a water separator or desiccant dryer and returned to the
immersion sump. For F-113 azeotropes containing ethanol, acetone, or
other water soluble components, a silica gel or other desiccant dryer
is necessary to prevent the removal of the water-soluble component with
the aqueous phase.
The freeboard of a vapor degreaser is the distance between the top
of the vapor zone and the lowest portion of the top of the degreasing
tank. This distance is controlled by the placement of the condensing coils.
For F-113 solvent systems, the minimum freeboard height should be 75%
of the degreaser width, measured at the vapor-air interface. The free-
board height is very important in protecting the vapor zone from dis-
turbance by air movement in the vicinity of the equipment. Disturbance
of the vapor zone can lead-to increased solvent vapor emissions into the
atmosphere. .,
Conveyorizetl degreasers employ the same operational procedures as
those for open-top degreasers, except that for conveyorized units, a
large portion (sometimes all) of the manual handling of the parts has
been eliminated. In the electronics industry, many of the F-113 users
employ a special conveyor system designed for printed circuits, in which
the boards are transported on a mesh belt through various combinations
of immersion, spray, and vapor cleaning cycles* Other common units used
with F-113 are the monorail conveyor and the crossrod conveyor systems^/
Essentially all conveyorized degreasers are hooded or covered. This en-
closure diminishes solvent losses from the system as a result of air
drafts in the vicinity of the unit.
Design and operational guidelines for vapor degreasing machines have
been detailed in the Dow report^./ and a recent ASTM publication^./ and
have been summarized in brochures by an F-113 manufacturer ..i^ai!/ These
guidelines are briefly stated as follows:
V-12
-------
1. Sump size: Surface area of immersion sump should be 50% greater
than size of the workpiece. Sump depth should allow complete immersion
of workpiece.
2. Solvent heating: Low-pressure steam is preferred. If electrical,
heat flux should not exceed 25 to 30 w/in? of heater surface. Solvent
boil-up rate (gallons/ hour) should equal volume of immersion sump.
3. Vapor zone: Vapor blanket should be sufficiently deep to cover
workpiece completely during transfer between sumps.
4. Spray rinse: If used, all spraying should be completely within
the vapor blanket.
5. Safety controls: Automatic heater cutoff switches should be
installed both above the vapor zone to prevent vapor loss due to con-
denser failure and in the boil sump to prevent overheating from low sol-
vent vent level or accumulation of soils.J£/
6. Work load movement: Entry/exit speeds should not exceed 10
ft/min.
7. Machine installation: Machine should be placed in a draft-free,
light traffic area with good ventilation.
For a more detailed discussion of these and other procedures, the
recent ASTM publication is recommended.
Sources of Solvent Loss
The major sources of solvent loss from vapor degreasers are basi-
cally the same as those stated previously for cold-cleaning operations,
namely: solvent evaporation; dragout; and solvent disposal practices.
Leakages from sources such as pump packings, valves, gaskets, joints,
sight glasses, etc., are normally very small, and are estimated to ac-
count for less than K. of total solvent consumption.^/ Evaporation or
diffusional losses result primarily from the mixing of solvent vapor
with air or water vapor. Relative vapor density is an important fac-
tor in the consideration of losses due to diffusion. F-113 has a rela-
tive vapor density of 6.47 (air =1), which is the highest of any com-
mon the common solvents used in vapor degreasing work.JLT./ This property
makes it possible to maintain a stable, definite vapor line at the top
of the vapor zone, which is less susceptible to disturbance from drafts
and operational procedures.
V-13
-------
Industry sources stated that a typical open-top vapor degreaser will
show a solvent loss of about .0.2 Ib/ft2/hr in idle condition, i.e., stand-
ing condition with no work being processed: under operating conditions,
the solvent loss rises to 0.5 Ib/ft^/hr.fft.0/ In terms of percentages,
this means that of the total losses due to evaporation and dragout, ap-
proximately 60% of the loss is due to dragout* Under idle conditions,
all losses are due to evaporative emissions* No consumption figures were
stated for used solvent disposal. The figure of 0.5 Ib/ft2/hr is a rather
standard figure that has been used by industry. Not all vapor degreaser s
will experience the same loss rates owing to the differing operating con-
ditions which would occur in actual industrial operations.^/
Figure V-3 shows data for the quantity of F-113 solvent loss as a
function of the condensing temperature at two different freeboard height/
width ratios. These data are for a vapor degreaser under idle conditions
and, as such, do not take into account losses that would occur during
the work cleaning process, i.e., dragout, poor operating practices, etc.
O.o
0.51
*!°'4
J3i 0.3i
! 0.2i
O.l
H/W - Freeboard Height to Width Ratio
50%~H/W-
I
I
: 75% H/W-
II l i
-30j-20i-10 0 10 20 30 ;40 50 60 ,70 80 90 100
Temperature, °F
Figure V-3. Vapor degreaser solvent loss as a function of
temperature
A representative of a major electronics and printed circuit manu-
facturer stated that losses from 100 and 150 gal. capacity, two-sump
vapor degreasers, equipped with freeboard chillers, totaled approxi-
mately 3 to 4 gal/dayJ£/ This equipment does not employ lip ventila-
tion, but each degreaser is hooded. Of these daily losses, the method
V-14
-------
of loss was estimated at 20 to 30% evaporation (diffusional losses), 60
to 70% dragout, and 5 to 10% solvent disposal* Dragout losses were prin-
cipally due to solvent entrapment in cavities of the work being processed.
For a continuous metal strip cleaner operating at a speed of 4 to 5 ft/
min, the percentage of solvent loss was approximately 45 to 50% evapora-
tive, 45 to 50% dragout, and 5 to 10% solvent disposalJ^./
According to the ASTM publication, the use of covered conveyorized
vapor degreasers decreases solvent consumption by at least 20%/ton of
parts cleaned.^/ This figure is not specific for F-113. A representa-
tive of a major electronics manufacturer states that, when using the 50%
F-113 plus 50% methylene chloride azeotrope, the largest source of evap-
orative emissions is through the entrance and exit ports of the conveyor
unit.II/
Potential Emission Control Techniques
As in the section on cold-cleaning operations, the potential emis-
'sion control techniques discussed herein are basically those presented
in the report by Dow Chemical Company with supplemental data from in-
dustrial sources. The various systems and/or methods for the control of
solvent losses from vapor degreasers that will be discussed are as fol-
lows:
* Operating practices
* Equipment
Carbon adsorption
Increased freeboard height
Refrigerated condensing coils
Refrigerated freeboard
Covers
Distillation
Offset sump systems
V-15
-------
Operating Practices - Good operating practices as used here include methods
of operating the equipment in a safe and economical fashion, while at the
same time effecting emission control, but not including distinct recovery
techniques* Good operating practices have been thoroughly discussed in
other reports and publicationsfLti^llZ/ and a lengthy discussion here is
unnecessary* However, a listing of these practices and very brief com-
ments abstracted from the literature are given*
1* Draft: Draft is one of the most serious causes of excess loss;
natural drafts should be held to a minimum; baffles may be constructed
to divert air flow*
2* Dragout: Farts should be arranged to provide maximum drainage;
work should remain in vapors until vapor temperature is attained; verti-
cal hoists should not exceed a vertical speed of 10 ft/min*
3* Shock load: Size of work load should not exceed 50% of the tank
area; if vapor zone drops more than 8 to 10 in*, work load is excessive*
4* Load and basket design: Farts carrier should not create a "pis-
ton effect." on vapor zone during loading; carrier should be free drawing*
5, Spraying: Manual spraying must be done well into the vapor zone;
fine, high pressure sprays should be definitely avoided.
6. Safety devices: A safety vapor thermostat should be used*
. * f
7, Leaks: Equipment should be inspected periodically for leaks
at pump packings, valves, gaskets, sight glasses, and others; hot sol-
vent evaporates rapidly so repairs should be immediate*
8* Maintenance: Equipment should be kept clean of accumulated oils,
metal chips, etc*; heat exchangers should be descaled*
9* Covers: Topic will be discussed later*
10. Distillation: Topic will be discussed later.
An indication of the effect that good operating practices can have on
solvent consumption is contained in a study conducted by one company
that used 1,1,1-trichloroethane instead of trichloroethylene in a vapor
degreaser«=2' In addition to some of the above guidelines, the degreaser
was covered during Low use and nonuse periods, the freeboard height was
maintained at 50%, and only properly trained personnel were allowed to
operate the degreaser. Over a 6-month operation test, solvent consump-
tion decreased by 80%.
V-16
-------
Carbon Adsorption - Carbon adsorption systems have been commercially avail-
able for about 17 years* Approximately 500 to 600 units are currently in
use, but only about 15 to 20 are used in F-113 applications* Of the 15
to 20 units, only a few are being used for recovery from F-113 degreasing
operations*!!/ The principal reason is the cost of the unit.
The primary functions of a carbon adsorption system consist of two
operations: adsorption and desorption*^^/ Most of these systems con-
sist of two tanks filled with activated carbon so that the adsorption
and desorption processes can be run simultaneously to provide a continu-
ous operation* Automatic valving is provided with the system, although
manually operated systems are available* A diagram of a typical system
is shown in Figure V-4* In the adsorption cycle, solvent-laden air enters
the system, and passes over the activated carbon bed where the carbon
collects the solvent; the cleaned air passes out the exhaust* A properly-
sized carbon adsorption system will remove about 95% of the solvent pres-
ent in the incoming air stream. The quantity of solvent present in the
air stream is dependent upon many factors, including how closely the opera-
tors adhere to good operating practices as well as the efficiency of the
ventilation system* One equipment manufacturer has given a rough estimate
of 200 to 1,000 ppm for F-113 degreasers.H/ Once the carbon bed has ad-
sorbed its working capacity of solvent (approximately 8% of the carbon
bed weight for F-113), the air stream is switched to the second bed and
the first bed is ready to be desorbed* The regeneration (desorption)
cycle is performed by injecting low-pressure steam into the carbon bed
to release the solvent from the bed. The resulting solvent-steam mixture
passes into a condenser where liquefication occurs. A water separator
collects the liquid and separates the two components by gravity*
In theory, the carbon adsorption system appears to be a rather sim-
ple procedure for F-113 systems; in practice* several other factors must
be considered* Adsorption systems for F-113 are not the same as for chlo-
rinated hydrocarbon solvents and are more expensive than the conventional
unitsJLI/ The carbon beds of the adsorption units tend to adsorb moisture,
and during the desorption process considerable quantities of water can
be adsorbed on the carbon bed* For the popular chlorinated hydrocarbon
solvents, this does not present a serious problem because during the sub-
sequent adsorption step, the chlorinated hydrocarbons will drive the
water from the bed, and no decrease in adsorption capacity will be ob-
served* When F-113 is used, water will effectively prevent its adsorp-
tion during the succeeding adsorption step unless the water is removed
prior to the cycle. The moisture is effectively removed by treating the
carbon bed with a stream of warm, dry air. Additional costs would be in-
curred for the extra blower, damper valves to allow the correct air flow,
and a heat coil to provide the warm air. Since an additional step is
V-17
-------
i
i-«
00
Solvent |
Laden [
Air | nput;
—lActivqted
Carbon Bed
'Water Separator
Adsorption Cycle |
i Desorptjon Cycle
Figure V-4. Typical carbon adsorber system
-------
required in the process, the time period between adsorption steps is
lengthened by approximately 15 min. If the bed dryer is employed prior
to the adsorption step, it is estimated that a 95% capture efficiency
can be expected for F-113.1I/
Host of the F-113 used in vapor-degreasing operations employs the
use of F-113 azeotropes rather than the pure material. For certain azeo-
tropes, carbon adsorption units can alter the composition of the azeo-
trope to a significant extent.JtziH/ A water-soluble component of a azeo-
trope will be lost during the regeneration (desorption) and water sepa-
ration process. For such materials, e.g., 96% F-113 plus 4% ethanol, 89%
F-113 plus 11% acetone, etc., the azeotrope will be adsorbed on the car-
bon bed, but after desorption and water separation the resultant solvent
will be pure F-113. the water-soluble component will be lost in the water
phase. Thus, the carbon adsorption units are most feasible for pure F-
113 and azeotropes containing nonwater-soluble components. For water
soluble components, it would be necessary to reformulate the azeotrope
after each adsorption/desorption process.
Carbon adsorption units are available in a number of sizes as shown
in Table V-l. The correct size for an installation is dependent upon the
volume of air flow required for ventilation, the quantity of solvent,
and the type of solvent to be adsorbed.
A calculation of the theoretical cost and savings relationship for
a carbon adsorption unit applied to an F-113 solvent system can be per-
formed. The assumptions used to generate the calculated relationships
are as follows:
1. Carbon adsorber pricing and operating data were obtained from
the report by Dow Chemical Company and Vic Manufacturing Company.
2. Equipment calculated on a 15-year depreciation rate with 10%
interest rate on the invested money.
3. Building space costs were not included since the adsorber unit
does not require usable floor space. It can be installed on a loft, on
the roof, or in other nonusable space.
4. Insurance was computed at 2%/year of the total equipment cost.
5. Maintenance was quoted by Vic Manufacturing Company at $100 to
$150/year for the Model 536 AD.
6. F-113 pricing was obtained from the Chemical Marketing Reporter,
June 21, 1976.
V-19
-------
Table V-l. COMMERCIAL CARBON ADSORPTION
Model
534 AD
536 AD
554 AD
572 AD
f 584 AD
M
O
' 596 AD
Lb of carbon
per tank
150
350
1,000
1,500
3,000
4,500
Motor
hp
1,5
3
15
20
30
50
CF
Maximum - both
tanks adsorbing
1,200
1,300
3,000
5,500
7,500
10,0001
M
Minimum -' one
tank des orbing
700
800
1,700
3,000
3,800
5,000
Working bed
capacity (F-113)
12
28
80
120
240
360
Price ($)£'
5,845
9,320
13,990
22,085
35,550
46,445
a/ Prices are FOB, Minneapolis, Minnesota, and do not Include shipping and installation*
-------
As stated previously, if a bed dryer is used prior to the adsorp-
tion process, a 95% capture efficiency is attained. However, a more im-
portant factor in emission control is the efficiency of the unit with
respect to the overall solvent cleaning system* For F-113, the liquid
dragout problems are not as severe as with the chlorinated hydrocarbon
solvents because of the vapor pressure differential* Because of this
differential and the overall smaller size of the degreaser with its
better ventilation, an overall system efficiency of 60 to 75% is at-
tained for F-113•£!/ In these calculations the widely quoted figure for
solvent emission of 0.5 Ib/ft^/hr is assumed, A Model 536 AD carbon ad-
sorption unit is chosen to be representative of the average size units
that, are employed with most F-113 systems but all of the various models
can be employed with this solvent* Pure F-113 is chosen for the calcula-
tions rather than any of the azeotropic solvents since the required in-
formation is more readily available for this system than for the azeo-
tropes. Except for price, it is doubtful that the parameters used in the
calculations will vary to an appreciable extent for the nonwater soluble
azeotropes. The calculated savings to cost ratio is shown in Table V-2*
These calculations are an adaptation of those presented in the report
by Dow Chemical CompanyJt*
If the same calculation is performed on a basis of three shifts per
day (6,000 hr/year), then the solvent savings per year are $3,510 and
the total annual operating costs, based on 360 desorption cycles per year,
are $2,407* This leads to a savings to cost ratio of 1*5*
A Model 536 AD, as used in Table V-2, requires a desorption cycle
about once every 3 days* At this low desorption rate, it would be pos-
sible to use a smaller unit (534 AD) and desorb about everyday. While
a daily desorption may pose some inconvenience, the operating costs would
be significantly reduced* Assuming a Model 534 AD, 280 desorptions per
year, and basically the same parameters as in Table V-2, a savings to
cost ratio of 0.81 can be calculated. This compares with a ratio of 0.53
for the Model 536 AD used in Table V-2.
Increased Freeboard Height - Current OSHA regulations state that in any
vapor degreasing tank the freeboard height shall be at least equal to
one-half of the tank width at its narrowest point or at least 36 in* in
height, whichever is shorter*.!' For F-113, industry recommendations have
been that the freeboard height be at least 75% of the degreaser width.
Several solvent producers, equipment manufacturers, and F-113 users im-
plied that while a freeboard/width ratio of 0.75 is recommended, some
of the F-113 vapor degreasers currently in operation do not meet this
ratio* New equipment is generally manufactured to these standards, but
older equipment still in use is likely to have a freeboard height/width
ratio of approximately 0*5*
V-21
-------
Table V-2.1 CALCULATED SAVINGS/COST RATIO FOR
F-113 USING CARBON ADSORPTION
MODEL 536 AD
Assumptions
' . - ' 2
1. Degreaser loss rate is 0.5 Ib/ft /hr
2. Overall recovery efficiency of 60%
3. Two-sump degreaser size of 14 in. x 20 in. (14 in/sump)
(?9_^?±'?^?AJL?±) _!!_?••§?_?.*• x. ?_.33 ft • 3.9 ft2
4, One shift per day (2,000 hir7yearT
Solvent and cost savings
0.50 Ib/ft2-hr x 3.9 ft2 x 2,000 hr/year x 0.60 =» 2,340 Ib/year
2,340 Ib/year * 13.2 Ib/gal x $6.60/gal> $l,170/year savings
Annual costs
Capital
Basic Model 536 AD $ 9,320
Drying cycle (207.) 1.864
$11,184
157. Installation 1,678
Total $12,862 x 0.13147£/ = $1,691
Equipment insurance (2%) $12,862 x 0.02 = 257
Maintenance = 150
Total capital cost per year $2,098
V-22
-------
Table :V-2. (Concluded)
Operating (desorb 120 times per year)!
Steam -90 lb/45 mln desorption cycle
1,000 Btu/lb
90 Ib/cycle x 120 cycles per year x
1,000 Btu/lb x $2.3/106 Btu = $ 25
Electric
2 hp x 0.746 kwh/hp x 2,000 hr/year x
$0.025/fcwh =75
Water
16 gpm x 60 min/hr x 90 hr/year x
$0.04/103 gal. = 4
Total operating cost per year $ 104
Total cost per year $2,202
Savings/cost ratio
$2,202
a/ 0.13147 is the factor for principal plus 10% interest over a 15-year
period.
V-23
-------
From data on solvent loss as a function of the condensing temper-
ature for a vapor degreaser under idle conditions (see Figure V-3), an
increase in the freeboard height/width ratio from 0.5 to 0.75 at a con-
densing temperature of 60° F (16°C) would result in a decrease in the
evaporative solvent loss of approximately 36%. If it can be assumed that
the shape of the curve for static losses would be the same at 60°F as
that shown for 72?F (see Figure V-l), then an increase in the freeboard
height/width ratio from 0.75 to 1.0 would show an emission control ef-
ficiency of about 35%. These figures are for static losses from a de-
greaser under idling conditions, and do not include losses attributable
to dragout, etc.
For large vapor degreasers, increases in freeboard height may re-
quire additional installation costs because of increased ceiling height,
increased pit depth, or increased platform height. It has been recommended
that the elevation of the top of an open-top degreaser be 42 in. above
either the floor level or operating level.J=L/ Generalized cost estimates
for this type of construction cannot be made since these costs would be
specific to a given facility. For the calculated savings/ cost ratio de-
veloped in Table V-3 for F-113, only the cost of the additional stainless
steel plus welding at the time of manufacture is considered. A cost of
$10/ft2 of 12 gauge stainless steel has been used.4./
In addition to the calculated saving-to-cost ratio shown in Table
V-3, a similar calculation for an increase in the freeboard height/width
ratio from 50 to 100% (60% emission control) would show, an annual sol-
vent savings! of (468 with an annual cost of $10 for a savings-to-cost
ratio of 46.8., As shown in Figure V-l, there appears to be little to be
gained in terms of solvent conservation by increasing the freeboard height
to width ratios appreciably above 1.0. While these data are for cold-
cleaning systems, the conclusion is equally valid for vapor degreasers.
Degreaser manufacturers believe that there is little to be gained by in-
creasing the freeboard height above a maximum of 4 ft, regardless of the
size of the vapor degreaser«£L/ A solvent producer quotes a maximum height
of 3 ft, regardless of size.6/
Refrigerated Condensing Coils - In this subsection the discussion will
center on the use of cooling devices to decrease the temperature.of the
vapor condensing coils to slightly above 32°F (0°G). One of the methods
for this decrease in temperature is by direct expansion refrigeration
but only to temperatures of approximately 35°F (2°C). (In this context,
the refrigeration discussed here should not be confused with a refrig-
erated freeboard chiller or "Gold Trap," which employs a completely
separate and different set of cooling coils placed near the top of the
degreaser and operates under a different principle at temperatures of
-20°F (-29°C). The refrigerated freeboard concept will be discussed in
the next subsection.)
V-24
-------
Table V-3. CALCULATED SAVINGS/COST RATIO
FROM INCREASED FREEBOARD HEIGHT
Assumptions
2
1. F-113 vapor degreaser size is 20 in. x 28 in. (3.9 ft )
2. Increase freeboard ratio from 75 to 100% (35% emission control)
2
3. Evaporative solvent loss is 0.2 Ib/ft -hr (see page V-23)
Estimated annual solvent loss (40 hr/wk)
0.2 Ib/ft^-hr x 3.9 ft2 x 2,000 hr/year » 1,560 Ib/year consumed
1,560 Ib/yearx 0.35 = 546 Ib/year'saved
546 Ib -r 13.2 Ib/gal x $6.60/gal = $273/year saved
Capital cost
Freeboard, increased from 15 to 20 in. (0.42 ft)
2
0.42 ft x 8 peripheral feet x $10/ft = $34
Annual cost
Capital: $34 x 0.13147-' = $4
Insurance (2% of capital) =1. .
Total cost $5
Savings/cost ratio
a/ 0.13147 is the factor for principal plus 10% interest over a 15-year
period.
V~-25
-------
As discussed previously in the general description of vapor de-
greasers, the primary cooling coils are utilized to control the top of
the vapor zone and to reduce evaporative emissions from this zone. Both
the condensing temperature and the freeboard height have a significant
effect on the quantity of evaporative emissions* The approximate quan-
tity of solvent loss as a function of condensing temperature for two dif-
ferent freeboard height/width ratios was shown in Figure V-3. For the
higher boiling chlorinated hydrocarbon solvents, ordinary tap water in
the primary condensing coils normally provides sufficient cooling. In
many instances tap water is also used for F-113 systems* However, at least
one equipment manufacturer recommends 60° F (16°C) or lower cooling water
for pure F-113 and the ethanol or acetone azeotrope.J^/ For the F-113 +
methylene chloride azeotrope, a cooling water temperature of 50°F (10°C)
is recommended* To achieve these recommended temperatures, it may be
necessary to replace the use of tap water in the primary condensing coils
with either chilled water or direct expansion refrigeration to condense
the solvent vapors* As shown in Figure V-3, a decrease in the temperature
in these coils can have a marked effect on the rate of evaporative emis-
sions*
Direct-expansion refrigeration operates on the same principle as
all other types of refrigeration* Instead of water in the primary con-
densing coils, a refrigerant fluid is used, and a small compressor unit
is attached directly to the vapor degreaser* Temperatures are thermostati-
cally controlled to preset values* It is not recommended that a water-
cooled system in operation be modified and retrofitted with direct-
expansion refrigeration*!^/ For those units in operation, it is advisable
-to add a water chiller unit instead of the refrigeration unit because
of moisture in the system and corrosion and scaling from the prior use
of water. Water-chiller units operate on the same principle as the water
chillers described earlier in this report in the chapter on refrigera-
tion* Basically, a small refrigeration unit is used to chill the water,
which is then circulated through the condensing coils*
The addition of a direct expansion refrigeration system would in-
crease the cost of a basic vapor degreaser by approximately $l,700«±ft'
Water chiller units would cost about $1,850 to $1,900, exclusive of cus-
tomer labor for installation. Calculated savings-to-cost ratios for each
of these units are shown in Table V-4,
In these calculations an initial cooling water temperature of 60°F
(16°C) has been assumed in accordance with the recommendations of an
equipment manufacturer* The percent emission control factors are based
on this temperature. However, if ambient tap water at 72?F (22°C) is
used for cooling the primary condensing coils, then the percent emission
V-26
-------
Table V-4. CALCULATED SAVINGS/COST EATIO
FBOM"REFRIGERATED CONDENSING COILS
Assumptions
2
1. Degreaser size of 20 in. x 28 in. (1.67 ft x 2.33 ft = 3.9 ft •)__
2. 75% Freeboard height/width ratio
3. One working shift per day (2,000 hr/year)
2
4. Solvent loss is 0.5 Ib/ft -hr
5. Initial cooling water temperature of 60°F (16eC)
Estimated annual solvent loss
0.5 Ib/ft2-hr x 3.9 ft2 x 2,000 hr/year = 3,900 Ib/year
Estimated annual cost conserved
1. Direct expansion refrigeration operated at 35°F (1°C) - 29% emis-
sion control (Figure V-3)
3,900 Ib/year x 0.29 T 13.2 Ib/gal x $6.60/gal = $565/year
2. Water chiller operated at 40°F (4eC) - 21% emission control (Fig-
ure V-3)
3,900 Ib/year x 0.21 * 13.2 Ib/gal x $6.60/gal = $409/year
Annual costs
Direct expansion refrigeration
Capital costs
Equipment: $1,700 x 0.13147-' = $223
Insurance (2%) = 34
b/
Inspection and maintenance-' = 50
Total capital costs $307
V-27
-------
Table V-4. (Concluded)
Operating costs
c/ . .
Electricity: 0.248 kwh=—x 2,000 hr/year x _ '
$0.025/kwh = I~12~
Total annual costs $319
Water chiller
Capital costs
Equipment: $1,875 x 0.13147 = $246
Insurance (2%) = 38
Inspection and maintenance— = 50
Total capital costs $334
Operating costs
Electricity: 0.249 kwh x 2,000 hr/year x
$0.025/kwh = $ 12
Total annual costs $346
Savings/cost ratio
Direct expansion refrigeration
Water chiller
1409
$346
a/ 0.13147 is the factor for principal plus 10% interest over a 15-year.
equipment lifetime.
b/ Mr. Richard Clement, Detrex Chemical Industries, Inc., Detroit, Michigan.
£/ Basic data supplied by Reference (b).
V-28
-------
control factors would be 31& for the water chiller at 40°F (4°C), and
38% for direct expansion refrigeration at 35° F (1°C). Using the two emis-
sion control factors for 72°F and performing the same calculation as in
Table V-4, the direct expansion refrigeration would show a savings-to-
cost ratio of 2*3, and the water chiller a ratio of 1.7.
With most vapor degreasers, the top of the vapor zone is approxi-
mately in the middle of the primary condensing coils, which means that
about 50% of the coils are above the top of the zone. Employing cooling
temperatures slightly above 32°F (0°C) has the added advantage of provid-
ing a small zone of cool air above the vapor zone. This cool air assists
in the prevention of vapor loss during the entrance and exit of the parts
to be cleaned. A concise evaluation of the control efficiency of this
type of cool air blanket is difficult to assess since it relies very
heavily on operating procedures and the size of the parts. One example
of a combination of factors is a midwestern company that cleans printed
circuits with the F-113 plus ethanol azeotrope. The company installed
a new vapor degreaser equipped with direct expansion refrigeration in
the primary condensing coils. With the new machine, operating practices
also improved over those used with the old machine. Solvent consumption
decreased from approximately 1,375 gal/year to about 550 gal/year or
about 60%..23_/ While these decreases cannot be directly attributed to one
specific control measure, they do provide an indication of the solvent
savings that can occur.
Refrigerated Freeboard Chillers - In the context of this section, this
terminology is meant to apply to those devices operating at temperatures
of 32° F (0°C) or colder. The device, termed "Cold Trap," was introduced
over 10 years ago but has encountered some sales resistance in the in-
tervening years.
While this emission control device operates in conjunction with the
normal primary condensing coils, it is based on a completely different
principleJ^llft' It consists of a set of coils in a compact shield placed
on the degreaser freeboard several inches above the primary condensing
coils. A small refrigeration unit is located near the degreaser to cir-
culate the refrigerant through the coils. Whereas the primary condensing
coils control the upper limit of the vapor zone by condensing the sol-
vent vapors, the refrigerated freeboard chiller coils, operating at
-20°F (-29°C), form an inversion layer of cold air above the solvent va-
por line to inhibit solvent vapor diffusion from the degreaser. Any mois-
ture in the air and solvent vapor present above the vapor line freezes
on the refrigerated coils. These systems are designed with an automatic
defrost cycle to periodically melt the frozen accumulation. The liquid
returns to the degreaser condensate trough and restores the efficiency
V-29
-------
of tlie heat exchange surface* During this defrost cycle, the unit is out
of service and the heat generated by defrosting may add slightly to the
emission level* The liquid water and solvent produced by the defrost
cycle is directed from the condenser collection trough, through the water
separator, and into the rinse sump* If the water separator is not suffici-
ently large, water contamination of the sump liquid will result. A sec-
ondary water separator may be necessary on some equipment to insure com-
plete separation* This is especially critical for F-113 azeotropes
containing water-soluble components* Oesiccant dryers must be used to
avoid destroying the azeotrope* In'addition, water contamination of F-
113 vapor degreasing solvents can also lead to equipment corrosion and
increased solvent evaporation*
The "Cold Trap" system has been accepted by the New York Department
of Labor in lieu of an exhaust system for controlling solvent emissions
generated in open-top vapor degreasing units. The only stipulations to
this acceptance are that the temperature of the cold air blanket must
be at least 70% lower than the boiling point of the solvent, and that
the circulating refrigerant must be 0°F (-17.flPC) or colder. The "Cold
Trap" system has been the center of considerable controversy during its
existence,24/
A calculated savings-to-cost ratio for the "Cold Trap" is presented
in Table V-5. Data on the pricing of refrigerated freeboard chillers,
design parameters, refrigeration coil pricing, and an overall system
efficiency of 35% were obtained from the report by Dow Chemical Company«Z'
A 15-year equipment life, 6% of capital cost for insurance and mainte-
nance, and a 10% interest rate on capital costs were assumed.^/ Since
most "Cold Traps" have been retrofitted to existing systems, the pricing
used in this calculation has been based on this mode of installation*
If this equipment were to be installed on a new vapor degreaser during
its construction, the incurred cost would be approximately 67% of the
price shown in Table V-5*£/ The savings-to-cost calculation is made for
the most common size F-113 vapor degreaser. Data for larger size units
can be compiled from the previously-referenced report on chlorinated hy-
drocarbon solvents^/
Covers - F-113 vapor degreasers normally are equipped with manually oper-
ated covers* An F-113 solvent producer stated that covers were normally
available as an additional option*^/ However, a major vapor degreaser
manufacturer said that all of the F-113 degreasers built by that company
are equipped with a roll cover and that metal covers are available as
an added option.^/ The roll covers operate on a principle very similar
to that of a windowshade* For covers greater than 4 ft^ in area, an auto-
mated power-driven assembly would be recommended*^./
V-30
-------
Table V-5. CALCULATED SAVINGS/COST RATIO FDR
REFRIGERATED FREEBOARD! CHILLERS
Assumptions
2
1. Degreaser size of 20 in. x 28 in. (3.9 ft )
2. One working shift per day (2,000 hr/year)
2
3. Solvent loss is 0.5 Ib/ft =hr
4. 35% System control efficiency
Estimated annual solvent savings
0.5 Ib/ft2-hr x 3. 9. ft2 x 2,000 hr/year = 3,900 Ib/year
3,900 Ib/year x 0.35 r 13.2 Ib/gal x $6.60/gal = $682/year
Total capital cost
Compressor (includes installation) = $2,635
Coils (8 ft x $32/ft) = 256
Total cost . $2,891
Annual cost
Capital cost: $2,891 x 0.13147-^ = $380
Operating: 0.5 hp x 0.746 kwh/hp x 8,760 hr- x 0.025/kwh = 87
Insurance and maintenance (6% of capital): 0.06 x $2,891 = 173
Total annual costs $640
Savings/cost ratio
- 1.1
$640
a/ 0.13147 is the factor for principal plus 10% interest over a 15-year
equipment lifetimeo .
b/ 24 hr/day; 365 days/year.
V-31
-------
Because of Che generally smaller size of F-113 degreasers as com-
pared to those using chlorinated hydrocarbon solvents, covers are much
more convenient to operate than for the larger degreasers* Because of
this convenience, the actual usage of covers is much more prevalent with
F-113 systems than with the chlorinated hydrocarbons; it has been esti-
mated that approximately 50% of the current users cover their systems
during periods of nonuse J^ili/
For a 24 in* x 32 in. F-113 vapor degreaser, a cover could be added
at a cost of approximately $150 to $200 Jd/ As the size of the open top
degreaser increases, the cost of a cover can become appreciable* It has
been reported that a cover for a 2.5 ft x 6 ft open top degreaser may
cost $1,500; a 4 ft x 12 ft unit costs $2.250; and a 5 ft by 40 ft would
cost $5,000.4/ These costs are variable, depending upon whether they are
retrofitted to existing systems and upon the material of construction.
The larger covers are. of course, all power-driven, automated mechanisms
which would contribute to their increased cost.
While it has been stated that the use of covers is a very favorable
emission control device.J^t/ no information regarding any extensive studies
was available with respect to precisely how effective this emission con-
trol technique would be for F-113 systems. An effectiveness of 35% has
been stated for the chlorinated hydrocarbons«4./ This efficiency may be
somewhat low for the smaller F-113 systems.
The specific type of cover and method by which it is used play an
important role in the emission control efficiency. Elastomer-gasketed
metal covers would provide a good.seal against vapor leakage during non-
use periods. However, if these covers are simply lifted from the top,
the rush of incoming air created by the lifting process will disturb the
vapor-air interface and create a "piston effect", with a resultant large
increase in solvent-vapor concentration in the air space above the de-
greaser. Lifting the cover in a slow and gentle manner would eliminate
or significantly reduce this "piston effect"; however, following this
procedure would be entirely dependent on the machine operator. The roll-
top cover reduces the effect of the incoming air, and hence the distur-
bance of the vapor-air interface, since the top of the degreaser is not
opened all at once to the atmosphere. If the roll-top cover is not sealed
by an elastomer gasket, leakages can occur when the top is closed. A roll-
top cover with an elastomer gasket is used by some manufacturers of F-113
vapor degreasers. A laboratory scale study of the effectiveness of covers
has been conducted that indicates an emission control effectiveness of
50% may be somewhat conservative, but would represent a generally accept-
able valuft-25/
V-32
-------
The calculations shown in Table V-6 are for a typical 20 in. x 28
in. (3.9 ft^) F-113 vapor degreaser in use for 8 hr/day. The solvent loss
is 0.2 Ib/ft^-hr, which is the quoted figure for a degreaser under idle
conditions.
Distillation of Used Solvents - Soils removed during the cleaning opera-
tion will accumulate in the boil sump of a two-sump vapor degreaser. A
typical F-113 vapor degreaser was depicted earlier in Figure V-2. Ulti-
mately, the dirty solvent must be either discarded or reclaimed. As the
control of solvent emissions directly into the atmosphere increases, the
quantity of used, or dirty, solvent will inherently increase. Thus, the
prevention of environmental emissions from discarded solvent becomes in-
creasingly important.
For general cleaning operations, the oil contamination of the F-113
in the boiling sump is generally limited to a. maximum value of 25 to 30%;
however, this value may be substantially lower for critical cleaning
operations*!!/ When this maximum value has been attained, the boiling
sump must be cleaned to dispose of the accumulated soils. Because F-113
is relatively low boiling, stable, and nonflammable, reclamation can be
simple if proper distillation equipment and operating procedures are used.
A number of options are available for the partial or complete recovery
of F-113 from a dirty solvent system.
One method employs the use of the two-sump vapor degreaser itself
for the partial recovery- of the F-113 soLvent.j-6/ The two-sump vapor de-
greaser is analogous to a simple one-plate still; and, using the high
temperature safety controls in the boiling sump, partial recovery of the
solvent can be achieved. While the recovered solvent may not meet new
product specifications in some instances, the recovery solvent is nor-
mally satisfactory for most uses. This recovery method must be conducted
while the equipment is not in use, since cleaning procedures cannot be
conducted while the reclamation is in progress. Very simply, the proce-
dure consists of removing the clean solvent from the condensate chamber
and the rinse sump. The safety control in the boiling sump is then in-
creased in temperature increments up to a mavftnum temperature of 140°F
(60°C). At this temperature, the composition of the liquid in the boiling
sump is approximately 50% F-113 and 50% soil. The distilled F-113 col-
lects in the condensate chamber and the rinse sump. At this point, the
liquid is drained from the boil sump and collected for further treatment
or disposal. Fresh solvent is added to the distilled solvent until the
normal liquid level is reached and the safety control is reset to its
original temperature.
V-33
-------
Table V-6. SAVINGS TO COST RATIO FOR THE USE OF COVERS
Assumptions
1. 50% Emission control effectiveness
2
2. 0.2 Ib/ft -hr solvent loss
3. One shift per day (2,000 hr/year)
Estimated annual solvent use
0.2 Ib/ft2-hr x 3.9 ft2 x 2,000 hr/year = 1,560 Ib/year
Estimated annual cost saved " ",
1,560 Ib/year x 0.5 -r 13.2 Ib/gal x $6.60/gal = $390/year
,*
Annual costs
Capital costs: $175 x 0.13147 = $23
Insurance (2%): $175 x 0.02 = 4
Maintenance (4%): $175 x 0.04 = 7
Total annual cost $34
Savings/cost ratio
$390 ,, •
$34- * U'5
V-34
-------
In-house distillation can be conducted with an external still, us-
ing either the original dirty solvent or the liquid remaining from dis-
tillation in the degreaser. In either case, the solvent is collected in
drums or pumped directly from the degreaser to the still system* Distil-
lation stills are normally incorporated directly into F-113 conveyorized
vapor degreasers and into open-top units with a solvent capacity greater
than 60 gal«£/ For the smaller units, however, a centralized still would
be used. The economics of the use of a still were previously discussed
in the section concerning cold-cleaning applications. With a normal stain-
less steel F-113 still, approximately 757. of the solvent can be reclaimed
by means of low-pressure steam heating. To attain maximum recovery of
solvent, live-steam injection into the bottom of the still should begin
when the still temperature reaches 170 to 180°F (77 to 82°C). Approxi-
mately 90% solvent recovery can be attained at a still temperature of
120°cJtZ/
A contract distillation service can be used to reclaim used solvent.
A number of solvent reclaimers are available, e.g., Ghem-Trol Pollution
Services, Inc., Custom Organics, and Solvent Recovery of New Jersey. The
cost of the reclaimed solvent is somewhat dependent upon the type of soils
present in the solvent and the desired purity of the final product. How-
ever, in almost all cases, the price of the reclaimed solvent is less
than that of new solvent.
According to a manufacturer of vapor degreasing equipment and a sol-
vent producer, very little of the dirty F-113 solvent from the small sys- -
terns (capacity < 60 gal.) is distilled or reclaimed.6,14/ pOj- conveyor-
ized systems and open-top degreasers of greater than 60-gal. capacity,
stills are normally incorporated into the system, and distillation of
used solvent occurs more frequently.
Offset Sump Systems - In certain instances, it may be possible to use a
vapor degreaser with an offset vapor generating sump (boiling sump). A
simplified diagram of this system is shown below in Figure V-5.
/-Condenser Jacket
J Land Coils
•'Water Separator
'-Heater
Figure V-5. Offset sump vapor degreaser
V-35
-------
The difference between this unit and the normal open-top vapor degreaser
lies in the fact that, in this case, the boil sump is essentially covered
and the only area with a vapor-air interface is above the rinse sump.
This reduced vapor-air interfacial area results in a decrease in solvent
loss by evaporative emission* Single sump units, with solvent spray capa-
bilities, have also employed this type of design. Where it can be employed,
this type of system could reduce vapor-air diffusional emissions by ap-
proximately 50% as compared to those of a conventional fully open-top
machine..!?/
The use of this type of system is not extensive at the present time.
Those systems in service are larger machines with a 2 ft x 3 ft or larger
opening and a solvent capacity of 250 gal. or more. Compared to a conven-
tional fully open-top machine of the same solvent capacity, the offset
sump design generally costs approximately 10% more than the conventional
maeh-tnA-25/
DRY CLEANING INDUSTRY
A thorough study of the various solvents, including F-113, used in
the dry cleaning industry was performed by the Environmental Engineer-
ing Division of TRW, IncJ>/ Their study was aimed at the support of new
source performance standards for the dry cleaning industry. Within the
scope of the study the following areas were evaluated: dry cleaning
processes and emissions, emission control technology, plant modifications,
environmental impacts, and economic impacts. To avoid a duplication of
effort, the information to be presented herein on the use of F-113 in
the dry cleaning industry was extracted Co a large extent from the TRW
study.
F-113 is the only chlorofluorocarbon used in the United States for
dry cleaning purposes. It is sold as a charged (about 0.1% cationic
/n\ -fc
detergent added) dry cleaning agent under the tradename of "Valclene-%"^
The dry cleaning industry consumes very small quantities of F-113 as com-
pared to the consumption of Stoddard solvent and percb.loroethylene.JjL2/
For 1974, the consumption of F-113 in this industry was approximately
2 to 4 million pounds..!/
The dry cleaning industry has three types of operations: coin-
operated, commercial plants, and industrial operations. At the pres-
ent time, F-113 is used only in the coin-operated and commercial opera-
tions. According to 1972 government statistics, the total number of
coin-operated establishments was 17,550 and the total number of commercial
*"Valelene®1 is a trademark of E. I. du Pont de Nemours and Company.
V-36
-------
plants was 28,422.2' For coin-operated installations, in which the gen-
eral public operates the equipment, less than 10% of these employ the
use of F-113; for commercial plants, operated by trained employees, ap-
proximately 45 to 50% are F-113 type machinesJLi/ In several commercial
installations, machines of the size used for coin-operated establishments
are employed but are operated only by trained personnel.
Dry cleaning machines are basically of two types: transfer machines
and dry-to-dry machines. Because of the high cost of F-113 cleaning sol-
vent, compared to perchloroethylene or Stoddard solvent, excellent sol-
vent recovery must be attained to allow these machines to be competitive.
Because of this, all F-113 machines are of the dry-to-dry type, in which
the washing and drying operations are performed in a single unit. Thus,
all F-113 machines have a built-in solvent recovery device. During the
drying cycle of these machines, the air flows from an air heater through
the cleaning drum (containing the cleaned material), a dry valve, and
a blower to the solvent recovery device. After the solvent has been re-
moved from the air stream, the air flows back to the heater and the cy-
cle is repeated. The average temperature of the heated air at the heater
discharge is 120°F (49°C); in the cleaning drum, the air temperature is
about 100°F (38°C). In the early models of the F-113 machines, carbon
adsorption units were used for solvent-vapor recovery from the air stream;
however, newer models employ the use of refrigerated coils in the closed
loop system* These units also include a filtration unit and a solvent
distillation system. The current models are completely closed to the atmo-
sphere during operation. F-113 machines also are soId-only as complete
packages. ' " *
For F-113 machines, the drying time and total cycle time for a load
of clothes are considerably shorter than for the same size load when
perchloroethylene is used. This is due to the higher evaporation rate
of F-113. As a consequence, the capacity can be smaller than for per-
chloroethylene units since more loads can be run with F-113 within the
same time period. For F-113, the most common size units are those with
12- and 25-lb capacities.
Solvent Consumption and Possible Emission Sources
As stated earlier, all F-113 units are dry-to-dry machines with
built-in solvent recovery methods, either dual tank carbon adsorption
or refrigeration condensation. The conversion from carbon adsorption
methods to refrigeration condensation occurred because (1) the carbon
adsorber was overly complex for coin-operated installation; (2) if
F-113 and perchloroethylene were used in the same plant, solvent con-
tamination could occur; and (3) the adsorber units required too much
floor space, as well as high steam consumption. However, with either
V-37
-------
type of recovery unit, F-113 machines show very low solvent consumption
rates compared to machines using the other two so 1 vents,!/
Because dry cleaning operation with F-113 is relatively new com-
pared to operation with the other two solvents, little information con-
cerning typical solvent consumption rates is available* Many dry clean-
ing plant operators discuss solvent consumption in terms of "mileage",
but this practice is being discouraged.^/ "Mileage" is the number of
pounds of fabric cleaned per 52 gal. drum of solvent consumed. Mileage
is proportional to the reciprocal of the solvent consumption rate (in
pounds of solvent per 2,000 Ib of fabric cleaned). Some of the solvent
consumption rates that have been quoted are shown below in Table V-7.
For perchloroethylene, a typical solvent consumption rate for a unit
without a carbon adsorber is 203, and with an adsorber, the value is
168^ To put the F-113 values in a different perspective, if one as-
sumes an average solvent consumption rate of 71, this corresponds to
the total loss of approximately 0.04 Ib of solvent per pound of clothes
cleaned. In terms of volume, this 0.04 Ib total loss is equivalent to
about 0.3 ounces («** 9 cc) per pound of clothes cleaned.
Table V-7. F-113 SOLVENT CONSUMPTION RATES;*/
Tester
IFI Research Center
Du Pont
Vic Manufacturing
Du Pont and EPA
Solvent consumption/
35
60
37
88-12 Ib capacity
71-25 Ib capacity
Comments
Laboratory tests by highly
trained personnel
Certification standard
for new machines
Laboratory tests by highly
qualified personnel
Units tested in a plant
operation by Du Pont
and EPA personnel; these
figures probably repre-
sentative of field per-
formance
a/ Pounds of F-113 per 2,000 Ib of cloth cleaned.
V-38
-------
Possible solvent emission sources from F-113 dry cleaning machines
are stated to be:5?21/
* Solvent retention in the cleaned fabric.
* Vapor emission losses from the cleaning drum caused by door-
opening between loads.
* Solvent retention in the filter cartridges.
* Solvent retention in sludge from the distillation system.
* Mechanical leakages, including seals and gaskets due to faulty
construction or improper fit.
According to the TBW study, solvent loss due to retention in the fabric
and mechanical leakages should be negligible in a we11-maintained and
properly operated machine. In tests conducted by an F-113 machine manu-
facturer, it was found that 10 to 12 g of solvent were retained in a
12 Ib load of clothes*2!/ This corresponds to approximately 0.002 Ib of
solvent per pound of clothes, or about 5% of the total solvent loss.
The filter cartridges are normally replaced after approximately
1,000 to 2,000 Ib of cleaning; a discarded cartridge contains about 3.5
to 5 Ib of solventjii^i/ In some machines a portion of this solvent can
be recovered by placing the used cartridge in the cleaning drum and run-
ning the unit through the drying cycle without the drum turning. A part
of the solvent will evaporate and be recovered*^./ No data were found for
actual quantities of solvent retained in the filter cartridges on a single
cleaning-drying cycle basis, or for the recovery of solvent using the
drying cycle technique. This filter device may be responsible for a con-
siderable portion of the solvent "consumption" in each cleaning-drying
cycle.
Oil sludge from the distillation system is normally collected after
about 1,000 to 2,000 Ib of cleaning. The total accumulation after this
quantity of cleaning is approximately 0.5 to 1.0 gal. of which about 5
to 10% is gniwMnft6»21/ Using an oil sludge density of 6.5 Ib/gal. and
a 10% solvent content, an average solvent content per pound of clothes
cleaned would be about 3 x 10"*^ Ib or approximately 8% of the total sol-
vent consumption per cleaning-drying cycle.
Potential Emission Control Techniques
F-113 dry cleaning machines must be well-designed and constructed
units with a minimum of solvent loss in order to remain competitive with
V-39
-------
the other lower-priced solvents* A conclusion from the TRW study was that
with good operating and maintenance procedures, a 5 to 6% reduction in
F-113 solvent consumption would be the maximum that can be attained*
These operating and maintenance procedures would include strict adherence
to the manufacturer's suggested maintenance program, as well as a record-
keeping system for solvent consumption and cleaning production. The an-
nualized costs for these procedures were considered to be negligible*
No other emission controls were recommended for F-113 machines •£/
V-40
-------
REFERENCES
1. Midwest Research Institute, "Technical Alternatives to Selected
Chlorofluorocarbon Uses," EPA Contract No. 68-01-3201, Task I,
Publication No. EPA-560/1-76-002, February 1976; also references
therein.
2. Arthur D. Little, Inc., "Preliminary Economic Impact Assessment of
Possible Regulatory Action to Control Atmospheric Emissions of
Selected Halocarbons," EPA Contract No. 68-02-1349, Task 8, Pub-
lication No. EPA-450/3-75-073, September 1975; NTIS No. PB-247-
115. '
3. "Fluorocarbons and the Environment," Report of Federal Task Force
on Inadvertent Modification of the Stratosphere (IMOS), Council
of Environmental Quality, June 1975, GPO No. 038-000-00226-1.
4. The Dow Chemical Company, "Study to Support Standards of Perfor-
mance for Organic Solvent Metal Cleaning Operations," Final Re-
port, EPA Contract No. 68-02-1329, Task Order No. 9, April 1976;
see also "Survey of Emission Sources," Subtask No. 1, Task Order
No. 9.
5. TRW, Inc., "Study to Support New Source Performance Standards for
the Dry Cleaning Industry," Final Report, EPA Contract No. 68-02-
1412, Task Order No. 4, May 1976.
6. Personal contact with E. I. Du Pont de Nemours and Company, May 1976,
7. "Cold Cleaning with Halogenated Solvents," ASTM Special Technical
Publication No. 403, American Society for Testing and Materials,
Philadelphia, Pennsylvania (1966),
8. Personal communication with Mr. Kaminsky, Le Nape Equipment Com-
pany, Plainfield, New Jersey.
V-41
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9. Personal communication with Mr* D. Schilling, Bendix Corporation,
Kansas City, Missouri.
10* Personal communication with Or. C. Schink, Tektronix, Inc.,
Portland, Oregon*
11. Personal communication with Dr. 0. Witherell, Collins Radio Com-
pany, Cedar Rapids, Iowa. ~~ -' ""''•' '-»•-••••- * -
12. Personal communication with Mr. J. Smallwood, Bendix Corporation,
Davenport, Iowa.
13. "Freon" T. F. Solvent, Bulletin No. FST-1, E. I. du Pont de Nemours
and Company.
14. Personal communication with Mr. G. Leith, Detrex Chemical Indus-
tries, Inc., Detroit, Michigan.
15. "Handbook of Vapor Degreasing," ASTM Special Technical Publication
310A, American Society for Testing and Materials, Philadelphia,
Pennsylvania, April 1976.
16. Freon® Solvents and Chemical, Tech. Brief TB-EQ-3, E. I. du Pont
de Nemours and Company.
17. "Vapor Degreasing with Freon® TF Solvent," Bulletin No. FST-3,
E. I. du Pont de Nemours and Company.
18. Freon® Solvents and Chemicals, Tech. Brief TB-EQ, E. I. du Pont
de Nemours and Company.
19. Personal communication with Mr. J. Hadel, Western Electric Company,
Lee's Summit, Missouri.
20. Staheli, A. H., Mechanical Engineering, p. 23, August 1973.
21. Personal communication with Mr. J. Barber, Research Director, Vic
Manufacturing Company, Minneapolis, Minnesota.
22. Larson, D. M., Metal Finishing, p. 42, October 1974.
23. Personal communication with Mr. Richard Clement, Detrex Chemical
Industries, Inc., Detroit, Michigan.
24. Rekstad, G. M., Factory, p. 27, January 1974.
V-42
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25. Personal communication with Mr. F. Madina, £• I. du Font de Nemours
and Company*
26. Freon® Solvents and Chemical, Tech. Brief TB-EQ-2, E. I. du Pont
de Nemours and Company*
27* Personal communication with Mr. W. Fisher, International Fabricare
Institute, Silver Spring, Maryland.
V-43
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APPENDIX
LIST OF REVIEWERS
A-l
-------
The following individuals and/or companies have reviewed all or parts
of the draft version of this report.
E. I* du_Pont de Nemours and Company,_Inc«
Wilmington, Delaware
Whirlpool Corporation
Benton Harbor, Michigan
Hussmann Refrigerator Company
Bridgeton, Missouri
Mr. Herbert T. Gilky
Air-Conditioning and Refrigeration Institute
Arlington, Virginia
Mr* S. P. Soling
St. Onge, Ruff, and Associates, Inc.
York, Pennsylvania
Detrex Chemical Industries, Inc.
Detroit, Michigan
VIC Manufacturing Company
Minneapolis, Minnesota
Dr. John Backus
Polyurethane Foam Division
Mobay Chemical Corporation
Pittsburgh, Pennsylvania
A-2
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TECHNICAL REPORT DATA
(Please read Inductions on the reverse before completing)
1. REPORTING.
EPA 560/1-76-009
3. RECIPIENT'S ACCESSIO*NO.
GAL sT^cmbELOGY AND ECONOMICS IN ENVIRONMENTAL
PERSPECTIVES; Task III - Chlorofluorocarbon Emission
Control in Selected End-Use Applications
S. REPORT DATE
November 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOH(S)
Thomas W. Lapp
Ralph R. Wilkinson
8. PERFORMING ORGANIZATION REPORT NO.
Howard Gadberry
Thomas Weast
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
Contract NO. 68-01-3201
12. SPONSORING AGENCY NAME ANO ADDRESS
Environmental Protection Agency
Office of Toxic Substances
Washington, D.C. 20460
13. TYPE OF REPORT ANO PERIOD COVERED
Final April-August 1976
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The purpose of this study was to identify the potential sources of emission for
three of the major end-use applications of F-ll, -12, -13, -113, and -114 and to iden-
tify current and potential methods for controlling emissions from these sources* For
identified methods of control, the efficiency of the method and the economics of its
application were determined, in applicable areas, the feasibility, cost, and effec- ,
tiveness of new or modified operating and/or maintenance procedures were studied as a
means of reducing emissions. The areas of study were refrigeration and air conditioning
plastic foam blowing agents, and cleaning and drying applications. This study did not
include an assessment of the risks associated with the environmental discharge of these
chemicals. Actual and potential sources of Chlorofluorocarbon emission were identified
in each of the three areas. Known methods of emission reduction, efficiencies^ _and _
economics are discussed for the fields of refrigeration and air conditioning and for
solvent and drying applications. Proposed methods were delineated for the plastic foam
blowing agent field.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Freons ®
Re frigeration
Air 'Conditioning
Blowing Agents
Solvents
Emission Control
Chemistry
Organic
Chemistry
18. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
196
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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- INSTRUCTIONS
. £ * * *
i. -*'*• '
2, LEAVE BLANK * v J -. , - . . 1 ^ . - - . ^ .. . .
tfaca»bfMch apart ndptat
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type oco.ittwt.dty,stBtB,aad ZIP cod*. Ujtaonx»etfaBitwol«nltof«no«piriTirinm>htancfay.
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It. CONTRACr/QRANTNIMBSR
12. SKNOOfllNaAOENCVNAMKANOAOOfleaS
13. TYPE OP REPORT-AND PERIOD COVERED
fadtat«mtnrimflnal.«te.i
M.
18. SUPPLEMENTARY NOTES . _, . . _ ______ _ .
Entet infontttion not inrftidod eiwwhera out tuefnl, such ac Aepued in tiooyaiatlpn with, Trtmhtion of, Fiwuited at cot
To-be pobiiihed in, Sopenedei,Sappinnnts, etc. - - - - -
18T ABSTRACT" - - ^ ~ ~ *
' of the moat ogmScant InfoiiiiatioB contained in* the-rapoft. If the.tppoct confiuii a
ngnifl^mt tnbUognpiijr or HfiBfifme mivey, imiiHon it hew.
KEY WORDS AND DOCUMENT ANALYSIS
W DESCRIFTORS - Select torn the Ttoannu of PngmMiing tnd Scientific Tarn the propn authorized tetnn that identify tto nujot
fonmipt of tte '•••••'•h snd ue Bif*fr if mly ipt^f^ md yteuM to be tued M index aulikii fov nfiiogfan. _ _ _ _
(b) tPEKiii-mRS AND OPEHiENDED TERMS • U«e JdentiSeo for project mme«. code moiet, equipment deagniton, etc. Uie open-
ended tenn milieu n detoiptoz fonn fox tboev subject* for whluh no deeoiDtor tadtti*
(c) COSATI FgLD GROUP • Ffeid and poap urigaaentt m to be titan from tiM 1963 COSATi Subject Catetpiy List Since the ma-
juiity of doCiiiimuitJ an f"t*Hftf n^iimir 10 nttuw, the Ptimujr Fleld/GfOBp uii(nnient(s) wfll be specific dbcipiine,-xm of hnom
endarar, or type of physical object TN apf ii'ff«*faMKi'> *73) (R«*«TM)
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