GLOSSARY OF TERMS AND DEFINITIONS FOR

SOLVENT
CLEANING IN INDUSTRY

(with a focus oil the Unit Operation System).

(DRAFT)

First Edition; May 1992
(First Revision; September 1993)
(Second Revision; June 1993)

Mohamed A. Serageldin, Ph.D.

tJ.S Environmental Protection Agency
Office of Air Quality Planning and Standards

(MD -13)

Research triangle Park, North Carolina 27711

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DISCLAIMER

This report has - not yet been reviewed by the Office of Air
Quality Planning and Standards, EPA, and approved for
publication. Any error is therefore, attributable to the author.
Mention of trade names or commercial products is not intended to
constitute endorsement or recommendation for use. Copies of this
draft glossary are available upon request.

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PREFACE

An important element in developing effective and defensible
regulations is using' consistent terminology and adopting terms
that are well illustrated. It is common during development of a
guidance or other technical document to fall into the trap of
using jargon or misusing general terms. It is also common to
see in documents that deal with a single subject the same word
used inconsistently to refer to different things. For that
reason early on in the cleaning project words and terms that
could be misunderstood were defined. For example, the term
"cleaning operation" is intentionally not used because it is
sometimes being used to mean "cleaning activities" such as wiping
and flushing and sometimes to mean an "item of equipment" such as
a parts cleaner. The term "equipment" was also avoided when
reference was made to a process or production unit to be cleaned.
The preferred term is "unit operation." The importance of this
distinction becomes clear in reference to the unit operation
system (UOS), since several items of equipment are involved in
addition to the unit operation being cleaned. Also, a multi-
stage distillation column is a widely used industrial "unit
operation." This process unit consists of three "items of
equipment"; a multi-stage separation column, a reboiler, and a
condenser). In our definition of a unit operation, we included a
number of non standard chemical engineering unit operations, such
as tanks and spray booth.

The UOS is a new material accounting and management concept.
It provides a specific approach to data recording which provides
insight into the destination of all pollution from a process,
whether it is allowed to enter the air, water or exit the
facility as a solid waste. For this reason a number of figures
and an example calculation were provided.

Relevant regulatory tents were also included in an attempt
to provide in one document most of necessary terminology for
regulatory development. Adoption of a common terminology is the
first step in furthering communication between the interested
parties.

Mohamed Serageldin, Ph.D.

June 1993

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TABLE CONTENTS

Page

1.	Glossary of Terms and Definitions	1

2.	Appendix A (list of figures)	11

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GLOSSARY OF TERMS AND DEFINITIONS [ref. 1]

ACT; see "alternative control techniques"

Alternative control techniques (ACT) [ref. 2]: - represent
a series of documents which are prepared to provide
technical information such as available controls for use by
State and local agency to develop their regulations. Sec.
183(c) of the Clean Air Amendments tCAAA) of 1990,
stipulates that ACTs "shall be issued for all categories of
stationary sources of volatile organic compounds and oxides
of nitrogen which emit, or have the potential to emit 25
tons or more of such air pollutants."

(NOTE: The States and local agencies are not required to
adopt recommendations made in an ACT as they would be in the
case of a control techniques guideline, CTG.)

Cleaning Activity: includes actions such as wiping,
brushing, flushing, or spraying. (The term cleaning
operation was intentionally not used in this list, because
it is sometimes used loosely to denote a unit operation,
such as a part cleaner.)

Cleaning Classifications: cleaning is grouped under three
main classifications: (1) Cleaning of external surfaces;
(2) Cleaning of interior surfaces/containers, and (3)
Cleaning of removable parts. The focus is on the "unit
operation" being cleaned.

Cleaning of external surfaces: under this classification,
the solvent must be applied to the "external surface" being
cleaned (as contrasted to the interior of tanks or pipes).
The "cleaning activities" (performed manually or
mechanically) may include mopping/brushing and spraying,
using "cleaning tools" such as rags, brushes, mops, and
spraying equipment. Surfaces that fall within this
classification include rollers in printing machines, wings
of aeroplane, floors, tables, and walls.

Cleaning of internal surfaces/containers: under this
classification the solvent must be applied to the interior
.of the '"unit operation" being cleaned, whether the task is
performed manually or mechanically. The "cleaning
activities" may include flushing, agitation, spraying, and
mopping/brushing. A combination of activities may be
required, depending on the shape and size of the "unit

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operation" and on the type residue that is being removed.
Surfaces may include the inside of tanks/vessels, batch
reactors, columns, heat exchanger, paint spray booths, and
fuel tanks.

Cleaning of parts: under this classification, the item
(part) is dipped in a container of solvent during cleaning
or the part is cleaned above the container by spraying or
wiping. Equipment (i.e., unit operations) used for this
cleaning task include part washers, batch-loaded cold
cleaners, ultrasonic cleaners, and spray gun washers. The
major "cleaning activity" may involve dipping or spraying.
Cleaning may, also, involve brushing and wiping.

Cleaning practices: means a repeated or customary action
that is specific to an industry. Some cleaning
practices will lead to pollution prevention and some
will not.

Cleaning tool: mean any item that is used for the purpose
of cleaning. This includes wiping rags, brushes, scrapers,
water jets

Closed-loop recycling (in-process recycling) fref. 31: reuse
or recirculation of a chemical material within the
boundaries of a "unit operation system." However, a
recovery or reclamation unit operation may be included

within the boundaries of the unit operation system if the
"unit" is

(1)	solely dedicated: the chemical is returned to be reused
for cleaning that same unit operation.

(2)physically	integrated: connected to the unit operation
being cleaned by means of piping, so that it is not possible
to exclude that "unit" when performing the material balance
around the unit operation system. The recovery or
reclamation unit may serve for purification, extraction,
distillation, filtration, adsorption or absorption.

NOTE:The condition for what may be termed "closed loop

recycling" is satisfied when a storage container is ,
involved if the entire process through completion of
. reclamation, is closed, with pipes or other comparable
enclosed means of conveyance. Condition No. 1 above
should also be true.

CTG: "control techniques guideline" - a document which

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provides guidance to States and local agencies for reducing
emissions of volatile organic compounds which contribute to
(stratospheric) ozone levels in non-attainment areas. These
are areas which violate the national ambient air quality
standard (NAAQS) for ozone. The Clean Air Act requires that
a source subject to a CTG meet reasonably available control
technology (RACT).

(NOTE: When EPA has issued a CTG for a source category,

State and local agencies cannot set in their regulations
(i.e., SIPs) RACT options for VOC sources that are less
stringent than those defined in the CTG. They can, however,
adopt more stringent control options. See also ACT)

HAP: " hazardous air pollutants" - A list of 189 compounds
established by congress. EPA may revise the list when
appropriate.

Life cvcle analysis (LCA): The scope of a life cycle
analysis depends on the elements encompassed within the
defined boundaries for the analysis. If the purpose of the
analysis is to perform a hazardous materials life cycle cost
analysis, then cost analysis will encompass all cost
elements for all phases of the system life cycle. This
includes acquisition, operation and support, and system
disposal. This type of analysis provides a decison-maker
with a tool for evaluating options to reduce pollution. The
example discussed above has a more local or national focus.
This type of analysis could be done by a plant or by an
industry.

The boundaries of a life cycle analysis may go beyond the
national boundaries. The analysis will involve looking at
the materials and processes being used to manufacture the
materials purchased by an industry for use in their
processes. The focus is likely to be different from one
that has a local orientation. This type of outlook is more
likely to be done by goverments and specialized organization
(e.g., a think tank). A unit operation system provides a
convenient building block for performing life cycle analyses
(see unit operation system).

In-process recycling: see "closed loop recycling"

Line flushing [ref. 4]: The flushing unit operation is the
infrequent process of completely cleaning out a paint
circulating system, which includes the paint mix tanks and
piping lines. This operation is only necessary when a

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system is inadvertantly contaminated or a new color is being
introduced to replace another system. Except for these
special situations line flushing is done annually.

Even in the case of closed-loop systems (Figure 3), some
losses can occur during flushing (i.e., through various
vents, from transfer operations and from paint mix tanks).
The information provided by the automotive industry indicate
that the loss from such system is around 10 percent for the
solvents used in this unit operation system.

MACT: " maximum achievable control technology" - It is the
maximum degree in of reduction in emissions of the 189
hazardous air pollutants (HAPs) listed in Sec. 112 (b),
including a prohibition of such emissions where achievable,
taking into account the cost of reduction, and any non-air
quality health and environmental impacts and energy
requirements. Source which emits per year, 10 tons of one
or 25 tons of one or more of the HAPs should meet MACT set
by EPA for that source category.

Maior source; means any stationary source or group of
stationary sources located within a contiguous area and
under common control that emits or has the potential to emit
considering controls, in the aggregate, 10 tons per year or
more of any hazardous air pollutant or 25 tons per year or
more of a combination of hazardous air pollutants,

Sec. 112 (a)(1).

Masking Agents: means a translucent or opaque material used
to cover/shield all or parts of a surface. Masking agents
are used in spray-booths to reduce the amount of solvent
needed for cleaning.

Nonattainment: "Any area that does not meet (or that
contributes to ambient air quality in a nearby area that
does not meet) the national primary or secondary ambient air
quality standard for pollutant," Sec. 107(d)(i).

Normalizing Parameters [ref. 5]; means a parameter for
making the emissions and other pollution data more useful.
Emission data in mass/time are not very useful for comparing
emissions from, e.g, two tank unit operation systems (UOSs),
if the size, number of tanks, solvent used, and time spent
cleaning are different in each case. An appropriate
normalizing parameters would be the total surface area
cleaned as this parameter may determine how much solvent is

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needed for cleaning and may also influence the rate of
evaporative emissions and solvent waste generated. The new
units would be mass per time per surface area cleaned. The
adoption of such units will generate usage factors
representative of certain cleaning scenarios.

On-site recycling (inside the boundaries of a facility)

Fref. 31 : means the reclamation of a solvent waste stream
that is returned to a different process other than from
which it was generated. This stage should be presented as
an independent "unit operation system," with the recovery or
reclamation unit operation (distillation, filtration, etc.,)
clearly defined. All storage containers directly connected
to the recovery or reclamation unit operation should be
included within the boundaries of the unit.operation system.
The emissions will also include solvent loss during cleanup
of the unit operation used for solvent reclamation in
addition to that accounted for on the basis of the
efficiency of the separation process.

Activities performed on-site which change the chemical
nature of the solvent, such as combustion or acid
neutralization are not included under this definition.

They are considered to be treatment operations.

Off-site recycling (outside the boundaries of a facility)
fref. 31: reuse or further use of a chemical material
accomplished after a recovery" or reclamation step. If the
reuse or further use of the chemical material is
accomplished without such a step the chemical material is
considered a feed stock for an off-site use. Activities
performed off-site which will change the chemical nature of
the contaminated material, such as combustion or acid
neutralization are not included under this definition. They
are considered to be "treatment operations."

Activities performed off-site which change the chemical
nature of the solvent, such as combustion or acid
neutralization are not included under this definition.' They
are considered to be treatment operations.

Ozone: a compound made up of three atoms of oxygen. This
compound is formed by reaction between volatile organic
compounds and nitrogen oxides. The reaction is energized by
sunlight. ¦	.

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o Pollution Prevention: involves practices aimed at

eliminating the creation of emissions or wastes at the
source. The practices include the use of new materials,
modification of equipment, and work practice changes.

Closed loop recycling is an acceptable pollution prevention
practice.

o Purging [ref 4]: The purging unit operation is the process
wherein individual paint applicators and/or small portions
of the paint line are emptied of one coating color, cleaned
and then filled with another coating color. This process
may one or more times in one day depending on the cleaning
practices adopted by a plant.

o Product substitution: means the replacement of any product
intended for an intermediate or final use with another
product intended and suitable for the same intermediate or
final use. This is considered a source reduction activity
if either the VOC emissions or the quantity of waste
generated is reduced.

o Protective covers: see "masking agents"

o RACT: see "reasonably available control technology"

o Reasonably available control technology [refs, 6 and 7]:

a control option to limit emissions from existing sources in
nonattainmnet areas. It is the lowest emission limit that a
particular source is capable of meeting by the application
of control technology that is both reasonably available, as

well as technologically and economically feasible
RACT is defined in control technique guidelines (CTGs).

o Recycling: A material is "recycled" if it is used, reused,
or reclaimed (40 CFR 261.1 (b)(7)). A material is "used or
reused" if it is either employed as an ingredient (including'
its use as an intermediate ) to make a product ; however a
material will not satisfy this condition if distinct
components of the material are recovered from metal-'
containing secondary materials) or employed on a particular
function as an effective substitute for a commercial product
(40 CFR 26.1(c)(5)). A material is "reclaimed" if it is
processed to recover a useful product or if it is
regenerated . Examples include the recovery of lead values
from spent batteries and the regeneration of spent solvents

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(40 CFR 261.1(c)(4). [See also closed-loop recycling (in-
process recycling); on-site recycling; and off-site
recycling.]

o Reclaimed fref. 2: A material is "reclaimed" if it is
processed to recover a usable product or if it is
regenerated, (see recycling).

o Source reduction fref. 21: means any activity or treatment
that reduces or eliminates the generation of VOC emissions
or waste. This includes (1) product substitution or
elimination, (2) technology changes, and (3) work practice
related changes.

o Stationary source: means any building, structure, facility,
or installation which emits or may emit any air pollutant,
Sec. Ill (a)(3).

o Source category: this term is used in reference to a list

(being developed by EPA) of all categories and subcategories
of major sources and area sources of the 183 HAP pollutants
listed in Sec. 112(b).

For example, the source categories Aerospace industries,

Auto and Light Duty Truck (surface coating), and Flat Wood
Paneling (surface coating) are listed under the industry
group " Surface Coating Processes." A more complete list is
given in Table 3.1 [ref. 83.

o Summary table of UOSs: plant wide solvent usage, emissions,
and waste can be summarized in convenient tables such as
that shown in Figure 5 to olan pollution prevention
objectives.

o ' Treatment fref. 21: It involves destruction or degradation
of the waste to produce material that is less toxic and has
a lower environmental risk impact, (see recycling).

o Unit operation (UP): means an industrial operation ,
classified or grouped according to its function in an
operating environment. There may be considerable variation
in unit operations from one industry to another. For
example a distillation column, a paint mixing vessel (tank),
a spray booth, a parts cleaner and a printing machine. A
unit operation may involve one or more items of equipment,

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e.g., a unit operation may include both a reactor and a
mixing vessel or several mixing vessels.

Unit Operation System (UPS): means the ensemble on which the
material balance is performed. It includes all possible
points/sources leading to evaporative emission losses
associated with the cleaning of a primary "unit operation,"
including losses during dispensing of solvent, handling
residual in cleaning tools (such as rags), solvent storage
and so on. (Examples of "primary" unit operation systems
are given in Figures 1 and 2 (for different control
situations). A "primary" unit operation system is the UOS
that An item of equipment that is used or designed for
cleaning parts is also a unit operation by definition,
therefore losses during removal of parts should also be
considered.

Emissions from solvent waste management unit operations
(e.g., recycling and treatment) result in "secondary
emissions." Emissions from each of the secondary unit
operations may be represented independently. They should be
computed from the corresponding UOSs - with all input and
output streams clearly identified. When such units,
however, are considered to be an "integral part" of the
"primary" "unit operation," the waste management unit should
be shown inside the boundaries of the UOS of which it is an
inseparable part (Figure 3). All input and output streams
for a UOS must, however be clearly identified. Emissions
from storage tanks containing virgin solvent should be
properly apportioned among the UOSs. This "cradle to grave"
material accounting concept is illustrated in Figure 4.

Used or reused Tref. 21: A material is "used or reused" if
it is either (1) employed as an ingredient (including use as
an intermediate) in an industrial process to make a product
(for example , distillation bottoms from one process used as
feedstock in another process). This term is used under
recycling.

VOC: see "volatile organic compound"

Volatile organic compound (VOC); means any compound of
carbon, excluding carbon monoxide, carbon dioxide, carbonic
acid, metallic, carbides or carbonates, and ammonium
carbonate which"participate in atmospheric photochemical
reactions.

That is any organic compound other than those the (EPA)
administrator designates as having negligible photochemical

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reactivity. The excluded compounds are mentioned in 40 CFR
Part 51, Vol. 57, No. 22, p. 3945, February 3, 1992. VOCs
may measured by EPA reference methods 24 and 24A (40 CFR
Part 60, Appendix A) or any approved equivalent method.

o Waste Minimization fref. 21; means the reduction, to the
extent feasible, of hazardous waste that is generated or
subsequently treated, stored or subsequently treated, stored
or disposed of. It includes any source reduction or
recycling activity undertaken by a generator that results in
either (1) the reduction of total volume or quantity of
hazardous waste, or both, so long as such reduction is
consistent with the goal of minimizing present and future
threats to human health and the environment. In order of
preference these are: source reduction, recycling, and
treatment.

o Water blasting: a cleaning practice which involves spraying
high pressure water on a surface to remove contaminants.

o Work practice: The main focus here is on the human aspects
of the industrial activities. This term is reserved for
specific industrial activities that lead to a reduction in
VOC emissions or waste. The activities include increased
operator training, management directives, segregation of the
waste solvent, practices that lead to a reduction in
cleaning frequency. It does not include the use of
equipment, such as solvent dispensers or modification of an
item of equipment.

References:

1.	M. A. Serageldin , "List of Definitions Applicable to the
Unit Operation System," Revised September 1992. US EPA;OAQPS
(MD-13) RTP 27711.

2.	The Clean Air Act Amendments of 1990, in Environmental Law.
Document prepared for the use of the Committee on Energy and
Commerce, House of Representatives, April 1991. U.S.
Government Printing Office (pp 159, 192, 607).

3.	"Pollution Prevention 1991: Progress on Reducing Industrial
Pollutants," Office of Pollution Prevention, Washington,
D.C. 20460; EPA21P-3003, October 1991.

4.	Letter from Prachan, E. A., American Automobile
Manufacturing Association (AAMA), to Serageldin, M. A.,
EPA/OAQPS; January 13, 1933.

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5.	M.A. Serageldin, "Different Approaches for Standards
Development (with an introduction to the unit operation
system concept), (revised draft, September 30, 1992); US
EPA,* OAQPS (MD - 13), RTP, NC 27711.

6.	"Glossary of Environmental Terns And Acronym List," US EPA;
Office of Communications And Public Affairs (A-107);
Washington DC, 20460; December 1989 19K-1002.

7.	EPA Guideline Series: Control of Volatile Organic Emissions
from Existing Stationary Sources - Volume II (Surface
Coating of Cans, Coils, Paper, Fabrics, Automobile, and
Light-Duty Trucks) EPA - 450/2-77-008 (OAQPS No. 1.2-073)
May 1977.

8.	Documentation for Developing the Initial Source Category
List (Final Report). US EPA; OAQPS; RTP, NC 27711;

EPA-450/3 - 91- 03 0, July 1992.

EPA\DEF0693.MAS

Please address comments to Mohamed Serageldin, (919) 541-2379:
OAQPS; MD-13; RTP NC 27711.

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V1

Solvent Recovered
(contaminant free)

Paint Line Flushing (closed loop) UOS (controlled emissions)

(R = dedicated recycling unit operation)

FIGURE 3

NOTE: Illustration copied from drawing provided by GM corporation
^Dearborn, Ml)for the cleanup solvent project) _ October 1991

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Virgin
Solvent



Storage



Primary Unit
Operation System

Emissions = + V2 + V3



Waste



Solvent

Storage

System Boundary

Emission Unit Operation System - uos

( Primary and Secondary UOSs)

FIGURE 4

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Summary of VOC Emissions (Ib/yr)

SOLVENT

UNIT OPERATING SYSTEM

SOLVENT

TOTAL

1

2

3

4

5

...15

















A















B















C















UOS
TOTAL













PLANT
TOTAL

FIGURE 5

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EXAMPLE

(Primary Unit Operation System)

EVAPORATIVE
LOSS. V,

(654)

EVAPORATIVE
LOSS, V2

(1.570)

EVAPORATIVE
LOSS, Vj
(392)

SYSTEM
BOUNDARY

SOLVENT
INPUT, S, ¦
(9.810)

SOLVi
CONT,

ENT
UNER





USED SOLVENT
OUTPUT, Sq(I-Xci)

(7,194)

S| (base ami.) - 330 gal/tank/changeout x 2 tanks x 1 change out/yr x 10.9 lb/gal - 7,194 Ib/yr

S| (replenish) - 0.05 gal/station/operation x 2 stations xtO operations/day x 240 days/yr x
10.9 to/gal-2,616 Ib/yr

St > St (base amt.) + St (replenish) - 7,194 to/yr + 2,616 to/yr - 9,810 to/yr
Vtot* V1+V2+V3 - SrSo (1-Xd)

Vtot- 0.05 gal/station/operation x 2 stations x 10 operations/day x 240 days/yr
x 10.9 lb/gal« 2,616 to/yr

vr- (0.25) 2,616 to/yr - 654 Ib/yr

V2* - (0.60) 2,616 Ib/yr -1,570 Ib/yr

V3# - (0.15) 2,616 to/yr - 392 lb/yr

Xci - 0.23 (i.e., 23 percent contamination by weight)"

Vtot-St-So (1-Xct)

So-(SrVTOT)/(i-Xci)

So - (9,810 Ib/yr - 2,616 to/yr) / (1 -0.23)

So - 9,343 to/yr

So (1-Xci) - 9,343 Ib/yr (1-0.23) - 7,194 to/yr

* Breakdown of Vtot estimated by facility manager

** Average provided by	(reclamation facility) for PRC's

Note: Ibs/yr represent total Ibs/yr from 2 stations described by this operation

Figure le. Clean-up No5-Mixer Parts Cleaning

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