Final Technical Progress Report
Report No. 6
24 June through 23 December 1972
GEOMET, Incorporated
Office of Experimental Development
2814-A Metropolitan Place
Pomona, California 91767
GEOMET, Incorporated
50 MONROE STREET
ROCKVILLE, MARYLAND 20850
301/762-5820
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Contract No. 68-02-0578
Development of Instrumentation for
Quantitative Collection of Total
Atmospheric Mercury from Ambient Air
Final Technical Progress Report
Report No. 6
24 June through 23 December 1972
GEOMET, Incorporated
Office of Experimental Development
2814-A Metropolitan Place
Pomona, California 91767
Authors: D. J. Sibbett and R. C. Wade
Publication Date: August 1973
Prepared for the Environmental Protection
Agency, Research Triangle Park
North Carolina 27711
GEOMET Report No. LF-215
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TABLE OF CONTENTS
1. 0 INTRODUCTION 1- 1
2.0 PROGRAM ACCOMPLISHMENTS 2-1
2. 1 Technical Approach 2-1
2.2 Phased Fulfillment of Program Goals 2-5
2.3 High-Volume Air Sampler Selection 2-12
2.3. 1 Hi-Vol Sampler Through-put Studies 2-15
2.4 Mercury Challenge Sources 2-16
2.4. 1 Particulate Mercury Challenge Sources 2-16
2.4.2 Elemental Mercury Vapor Source 2-17
2.4.3 Organic Mercury Challenge Sources 2-19
2.4.4 Ambient Air Challenges 2-22
2.5 Air Train Challenge Apparatus 2-22
2. 5. 1 GEOMET Model 103 - Mercury Air Monitor 2-29
2. 5. 1. 1 General Description 2-29
2. 5. 1. 2 Improvements to Model 103 2-32
2.5.1.3 Details of Changed Features 2-34
2.6 Mercury Absorbent Development 2-39
2.6. 1 Selection of Adsorbents 2-39
2.6.2 Particulate Mercury Collector 2-44
2.6.3 Elemental Mercury Adsorbents 2-44
2.6.3.1 Commercially Available Silver-Treated
Adsorbents 2-51
2.6.4 Organic Mercury Absorbents 2-53
2. 7 Prototype Collection System 2-54
2.7. 1 General 2-54
2. 7. 2 Hi-Vol Collection Plenum 2-55
2.7.3 Collection Canister Design 2-67
2. 7.4 Recovery Analysis System 2-73
2.7. 5 Demonstration to EPA Program Monitor 2-73
2.8 Recovery Analysis Procedures 2-82
2.8. 1 Recovery System Description 2-82
2.8.2 Analysis of Particulate Mercury Samples 2-85
2.8. 3 Analysis of Adsorbent Pellets 2-86
2.8.4 Analysis of Charcoal Absorbent 2-90
2.8.5 Other Analysis Methods 2-91
2.8.6 Additional Analysis Equipment 2-92
2.9 Prototype System Test Data 2-96
2.9. 1 Collection Efficiency Tests 2-96
2. 9. 2 Ambient Air Monitoring for Elemental
Mercury 2-106
11
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TABLE OF CONTENTS (Con't.)
Page
3.0 CONCLUSIONS, RECOMMENDATIONS AND
COMMERCIAL PRICE ESTIMATES 3-1
3. 1 Summary 3-1
3.2 Recommendations 3-3
3.3 Commercial Price Estimates 3-5
4.0 EQUIPMENT DEVELOPMENT TABULATION 4-1
iii
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FIGURES
2- 1 Assembled Sampler and Shelter 2-13
2- 2 Commercial Hi-Vol Samplers 2-14
2- 3 Elemental Mercury Vapor Source 2-18
2- 4 METRONICS DYNACAL Permeation Tubes 2-20
2- 5 GEOMET Model 103 Instrument Calibration 2-23
2- 6 Mercury in Air Sampling Train 2-25
2- 7 Canister Holder and Sampling Plenum for
Hi-Vol Sampler 2-26
2- 8 Collection Canister/Hi-Vol Sampler Interface
Configuration 2-27
2- 9 Final Collection Plenum Configuration 2-28
2- 10 Complete Prototype Instrumentation Assembled
with Test Apparatus 2-30
2-11 Function Diagram, Model 103 2-31
2-12 Model 103 with Catalytic Converter 2-31
2-13 Electrical Wiring Schematic, Model 103 2-33
2- 14 Recent Improvements in Lamp Controls and
Adjustments 2-35
2-15 Recent Improvements in Model 103 Grid Control
Circuitry 2-35
2-16 Twenty-Four Hour Collection Efficiency Tests,
Silver on Alumina Pellets 2-48
2-17 Hi-Vol Collection Plenum Installed in Place 2-56
2-18 Collection Plenum Canister Assembled Onto
Hi-Vol Sampler 2-57
2-19 Hi-Vol Collection Plenum Details 2-58
2-20 Plenum Tube 2-59
2-21 Flange Ring 2-60
2-22 Thread Ring Modification 2-61
2-23 Plenum Tube Weldment 2-62
2-24 Orifice Housing 2-63
2-25 Retaining Ring 2-64
2-26 Pressure Tube 2-65
2-27 Air Bypass Control Ring 2-66
2-28 Collection Canister /Hi-Vol Sampler
Prototype Interface Configuration 2-69
2-29 Prototype Multiple-Use Collection Canisters 2-70
2-30 Canister Body 2-71
2-31 Canister Screen Closure Details 2-72
2-32 Recovery Crucible Furnace Details 2-75
2-33 Furnace Cover 2-76
2-34 Crucible Cover 2-77
2-35 Outlet Tube 2-78
2-36 Collect Tube 2-79
2-37 Crucible Details 2-80
2-38 Disc 2-81
IV
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FIGURES (Con't.)
2-39 Mercury Challenge Collection Method 2-83
2-40 Analytical Method 2-84
2-41 Conceptual Mercury Recovery Resistance Furnace 2-88
2-42 GEOMET Model 103 Calibration Data 2-116
2-43 Calibration of Perkin-Elmer Model 303
Atomic Adsorption Spectrophotometer 2-117
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TABLES
2-1 Phase Program Goals 2-7
2-2 Prototype System Test Data 2-100
2-3 Analysis in Ambient Air Test, GEOMET Model 103 2-108
2-4 Atmospheric Test, GEOMET Model 103 Data 2-114
2-5 Ambient Air Test, Canister Method - Analysis of
Silver/Alumina Adsorbent 2-119
4-1 Equipment Tabulation Sheet 4-2
VI
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Section 1. 0
INTRODUCTION
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Section 1. 0
INTRODUCTION
GEOMET, Incorporated submits the draft of the Final
Report under Contract 68-02-0578 in accordance with the Reports of
Work Requirements as stipulated by the contract. This report pro-
vides a description of the effort expended over the period of 24 June
through 23 December 1972.
The objective of the program for Development of Instrumen-
tation for Quantitative Collection of Total Atmospheric Mercury from
Ambient Air was to design, develop and fabricate a prototype collec-
tion device for the quantitation of mercury in air in the three major
forms: (1) inorganic and organometallic particulates, (2) inorganic
and organometallic vapors, and (3) elemental mercury at levels up to
3
a threshold limit value of 100 micrograms/M . The collection device(s)
and attendant processing techniques are compatible for utilization in
or with Hi-Vol samplers of the National Air Survey Network for air
sampling in the field. Design of the collection devices is oriented
to obtain quantitative mercury retention, to give convenient packaging,
storage and shipping, and to give ease of analysis at centrally
located laboratories after use.
The scope of the contract effort included the design, fab-
rication and testing of prototype collection devices, adaptation of
those devices to Hi-Vol samplers, provision of techniques and pro-
cessing equipment for analysis of the collected mercury forms, full
1-1
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system quantitative testing, and delivery to EPA of the set of
prototype instrumentation following a demonstration of the effective-
ness of the system. The overall aim of the program was to provide
qualified prototype instrumentation capable of being put into the field
on an economical large-number basis.
1-2
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Section Z. 0
PROGRAM ACCOMPLISHMENTS
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Section 2. 0
PROGRAM ACCOMPLISHMENTS
The effort expended under this program covered the
development of a Prototype form of the mercury collection device.
The collection method allows the total and quantitative collection and
separation of the three forms of mercury - (1) particulate, (2) ele-
mental and (3) inorganic and organomercury vapors. These individ-
ual samples may be easily packaged and transported back to some
centralized laboratory for analysis. The analysis measures the
mercury content in each collected solid phase, corresponding to the
forms indicated above and thus provides total mercury values regard-
less of the mercurial forms present in the sampled ambient air.
2.1 TECHNICAL APPROACH
The technical approach for the Development of Instrumenta-
tion for Quantitative Collection of Atmospheric Mercury from Ambient
Air was designed to meet all the requirements stipulated by the EPA
in Contract No. 68-02-0578. The program was carefully structured
to be compatible with the phases contained in the Contract Scope of
Work (Reference Section 2. 2 below). In addition, the program was
oriented to provide the necessary technical data from practical
testing of hardware developed under the contract.
Specific areas of development effort were 1) the minimal
modifications to a standard Hi-Volume air sampler while incorpora-
ting the new instrumentation, 2) definition of collection canister con-
2-1
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figuration and selection of absorbents for all forms of mercury, and
3) utilization, as a baseline configuration, of existing chemical and
electromechanical devices for analysis of collected mercury samples.
A stepwise approach to the solution of these problems was created in
order to optimize the accomplishments during this short duration pro-
gram.
Hi-Volume Sampler Modifications
In accordance with the contract Scope of Work, prelimin-
ary design concepts relating to the collection system evolved around
the insertion of collection canisters into the body of a typical Hi-Vol
sampler. This concept precluded any physical change to the sampler
itself, but did increase the sampler height. It is expected that this
added canister plenum, incorporating threaded ring fittings, will be
adaptable to all commercially available Hi-Vol samplers being mar-
keted in the continental United States. The only remaining assembly
criteria is the varied construction details of shelters in which the
Hi-Vol samplers are operated. GEOMET chose a UNICO 550 Turbine-
Jet High-Volume Air Sampler (marketed by the Environmental Science
Division, Bendix Corporation) for use on this program. This particu-
lar sampler is housed in a rather inexpensive plywood shelter. Since
the sampler is supported in place by the upper edge of the incoming
air funnel duct, the Hi-Vol and collection plenum now extends below
the sides of the shelter. This in no way affects the operation of the
sampler, but does allow the Hi-Vol air through-put gage to be some-
what exposed to the open air and brings the exhaust port closer to the
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ground. GEOMET also owns a High-Volume sampler marketed by
the PRECISION Scientific Company. This Hi-Vol is supported by a
ring around the blower motor housing, rather than by the air inlet
ducting. When installed in the supplied aluminum shelter, the Hi-Vol
and plenum system protrudes above the shelter at the top prohibiting
positioning of the hinged roof-cover. It is, therefore, concluded that
while the simple utilization of the collection plenum obviates any mod-
ification to the Hi-Vol sampler, some slight modifications may have
to be made on specific Hi-Vol sampler shelters currently in use in
the National Air Sampling Network (NASN). Any modifications would
consist of increased side protection and be dependent on the type of
shelters in use.
Details of the collection sample plenum for the Hi-Vol
samples are included in Section 2. 3, below.
Collection Canister Configuration and Absorbents
In the proposal for this program, GEOMET submitted con-
ceptual designs for the Prototype instrumentation. As a part of the
total system, the idea of using stacked "canisters" for positioning
and support of the mercury absorbents with the Hi-Vol was established.
During the program, various developmental parameters were exploited
and the Prototype design evolved as a result of testing several con-
figurations. Several limiting factors became readily apparent. The
maximum height and diameter of two or more collection canisters was
determined by Hi-Vol sample air through-put, necessary adsorbent
volume as determined by the collection efficiency of the test absor-
2-3
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bents, and the wide range over which quantitative mercury collection
must be made. The final configuration of the canisters was pre-
dicated on results of testing to explore these limiting factors. The
rationale for canister size, while tied directly and unequivocally to
absorbent bed size, was to provide space for enough absorbent (in
the elemental mercury collection canister) to cover mercury levels
3 3
spanning five (5) decades, i.e. from 1 ng/M to 100,000 zig/M of
mercury. Also, the constraint of final analysis of the sample by
commercially available instruments was superimposed onto the canis-
ter design calculations, and subsequent testing was utilized to ascer-
tain the minimum canister sizes which would provide enough sample
of any range of collected mercury for meaningful analysis. Of
lesser importance, was the actual canister configuration. Here items
such as materials of construction, handling and packaging were investi-
gated. The collection canister design for the Prototype system is a
result of the investigation of these factors. Further details of the
current design are found in Section 2.6.3 and 2.6.4 of this report.
Absorbent development was based on the premise that both
EPA and GEOMET wanted several non-sole source commercial sup-
pliers of absorbent for the Prototype system. GEOMET examined
several potential sources of commercial collection media and pur-
chased batch lots of treated aluminas and charcoals for the collec-
tion of elemental and organic mercury. Finally, GEOMET set out to
manufacture batch lots of treated alumina for elemental mercury col-
lection. None of the tested, commercially available absorbents were
2-4
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comparable in performance to the GEOMET product. Therefore, all
elemental mercury collection made during the final test periods of
the program were made with the GEOMET prepared absorbent.
Developmental details of this effort are found below in subsections
of 2.6.
Analysis of Collected Mercury Forms
GEOMET utilized, as a baseline system, the wet chemistry
method for determination of mercury as described in the Federal
Register, Volume 36, No. 234 - Tuesday, December 7, 1971. GEOMET
did, however, institute unique pre-processing steps as well as add other
types of instrumentation between the liquid impinger system and the
Atomic Absorption Spectrophotometer (AAS). A special technique was
also developed for the analysis of particulate mercury found on the Hi-
Vol filter. The analysis procedures finally developed, while still in
the prototype stage, fully satisfied the needs of the program as speci-
fied in the Scope of Work and appear to offer an accurate and precise
method of rapid testing of samples. Specific procedural steps are
found in Section 2. 7 below.
2.2 PHASED FULFILLMENT OF PROGRAM GOALS
In Exhibit "A" of the contract, Scope of Work, the Environ-
mental Protection Agency provided a program effort outline divided
into five (5) Phases. Inasmuch as this phased effort has considerable
overlap in tasks between phases, GEOMET reordered some of the
tasks for a more chronological approach to the development of the
2-5
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instrumentation. In order to clearly demonstrate the GEOMET res-
ponse to the Scope of Work, the following table is provided which
indicates Phase task and the corresponding GEOMET development.
Reference is also provided to Sections of this report wherein addi-
tional data may be found.
2-6
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Table 2-1 Phase Program Goals
Scope of Work;
Phase I
GEOMET Response
to
The Contractor shall design, fabricate, and
evaluate a prototype device for the quantitative
collection of airborne mercury and its com-
pounds (inorganic salts and organometallic
vapors) from the ambient air. The device
shall have the following performance charac-
teristics:
A. The prototype device shall be constructed
for ease of handling in field operations
and shall be simple and compact in struc-
ture to facilitate low cost shipment by mail
to central laboratories following sample
collection.
B. It is desired that the collection device be
used with the Hi-Vol samplers of the
National Air Survey Network as an attach-
ment to their present collection system.
C. Construction materials shall be economi-
cal, to allow for eventual production of
large numbers of the collectors for nation-
wide surveys.
D. The materials of construction shall have
a low mercury background and be readily
cleaned of any mercury collected.
The collection canister design is simple, inex-
pensive and compact. The plastic cylinders
may be reloaded in the field or mailed to lab-
oratories in commercially available containers.
(Section 2.6, 2.7, and 3.0)
The collection plenum inserts into the Hi-Vol
sampler without modifications to the Hi-Vol or
use of special tools. (Section 2. 7. 2)
Initial collection plenum construction is of alum-
inum. Prototype canisters are of PVC plastic.
It is conceivable that ultimately all parts could
be fabricated from low cost plastic materials.
(Sections 2. 7. 2 and 3. 3)
Current materials are free from mercury, and
it is not apparent that these materials are absorb-
ing mercury during sample testing. (Section 2. 7)
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Table 2-1 Phase Program Goals (Con't. )
Phase I (Con't. )
E. The collection device shall be capable of
retaining the collected mercury in all its
forms in a stable state for several -weeks
and to quantitatively release the mercury
for analysis.
The collection device shall be capable of
quantitatively collecting all forms of mer-
cury from the ambient air at flow rates
common for the Hi-Vol sampler (20 CFM
or better). Its capacity for retention of
mercury and its compounds should be for
all mercury present in a 24-hour consecu-
tive sampling period. This requires the
capability of handling mercury concentra-
tion ranges from the natural background
levels of a few nanograms per cubic meter
to the threshold limit value of 100 micro-
grams per cubic meter.
The collection device may consist of sev-
eral stages or compartments with each
specific for a particular form of mercury
found in the ambient air. The three forms
of mercury to be collected separately are
elemental mercury, inorganic and organo-
metallic mercury in particulate form, and
inorganic and organometallic mercury
vapors.
IS)
i
00
GEOMET Response (Con't.)
Absorbents clearly absorb the levels of mercury
stipulated by the Contract. Collection efficiency
runs show that some slight difficulty remains in
uniform recovery of all absorbed mercury vapor.
Careful packaging will hold samples in stable
state for several weeks. (Section 2. 8. 3)
The collector separates particulate, elemental
and combined mercury (vapors) onto a glass
fiber filter, a silver /alumina adsorbent and acti-
vated charcoal, respectively. Sampling rates of
20 CFM or better have been utilized. Several
long duration sample runs at Hi-Vol through-put
of 220 CFM were made during the course of the
program. Challenges varied from 4. 5 x 10 -
/ซg/M3 (elemental) to 118 yซg/M3 (organic). These
combined mercury runs are reported in Section 2. 9.
The Prototype system utilizes a standard Hi-Vol
fiberglass filter for inorganic and organometallic
particulate forms, a canister stage for elemental
mercury and for inorganic and organometallic
vapors. (Sections 2. 6 and 2. 7)
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Table 2-1 Phase Program Goals (Con't. )
Phase I (Con't. )
H. The collection device shall be able to sep-
arate for independent analysis the three
major forms of mercury (elemental, parti-
culate, organic vapors).
I. A removal procedure for the collected mer-
cury shall be developed so that the mercury
can be analyzed by readily available analy-
tical instruments, both inexpensive and soph-
isticated.
J. A delineation of the types of instruments
that can be used for these analyses and
N proof of their capabilities shall be pre-
pared and submitted to the Project Officer.
GEOMET Response (Con't. )
Collection stages (previous page) hold each form
of mercury in a separate state for independent
analysis. (Sections 2. 6, 2. 7 and 2. 9)
GEOMET has developed unique apparatus and/or
methods for recovery analysis of collected mer-
cury. See Section 2. 9.
Instruments, by type, for similar processing
are noted in Section 2. 8. 6.
Phase II
The fabricated collection device shall be checked
to establish its efficiency for collection of air-
borne mercury and its compounds. Known mer-
cury standards in several chemical forms (ele-
mental, inorganic, organometallic) shall be
used to determine their collection characteris-
tics. Modifications should be made to optimize
the collection efficiency of each species. Sev-
eral environmental factors shall be checked for
their influence on the collection efficiency of the
device. These are climate factors such as tem-
perature in the temperate range, moisture, dust
load, and winds. Other fact orb like gaseous pol-
lutants (H2S, SO2, NOx, phenols, hydrocarbons)
shall be checked for their effect on the collection
efficiency for mercury.
The Prototype system was effectively challenged
by varied amounts of elemental vapors, organic
mercury, and solid particulate mercuric com-
pounds. Collection efficiency runs were carried
out and reported on a monthly program basis.
Contaminant gases were superimposed over the
combined mercury form challenges. Limited
ambient air challenges were carried out with the
total system. (Section 2. 9-all subsections. )
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Table 2-1 Phase Program Goals (Con't. )
Phase III
A transfer step to remove the collected mer-
cury from the collector to an appropriate anal-
ytical instrument is envisioned. The step could
require the development of a handling system
for transfer of the mercury vapor. If such a
system is developed, it shall be tested for quanti-
tative transfer and clean-up to the previous back-
ground levels for mercury.
GEOMET Response
GEOMET utilized a modified Hatch and Ott
procedure for processing the elemental and
organic samples through the analysis pro-
cedure. Special handling and processing com-
ponents were fabricated to aid in the analysis
of the adsorbents. (Section 2.8).
Phase IV
I
H
o
Detailed scientific data shall be furnished to
support all claims on the efficiency of mercury
collection. Similar data shall document the
effect of atmospheric variables and gaseous pol-
lutants on the collection efficiency. Prototypes
of the developed collection device and any trans-
fer system shall be furnished.
A tabulation of the specifications of all equip-
ment developed under this contract shall be
submitted to the Project Officer with the final
report on this project. If a transfer or sample
processing step is necessary before the mercury
sample can be analyzed, a written procedure for
this operation shall be furnished with the final
report.
Comprehensive testing of the Prototype system
was carried out, including several long dura-
tion (^24 hours) runs. The results of these
tests are discussed and tabularized in the sub-
sections under Section 2. 9.
The tabulated equipment list is presented in
Section 4. 0. Procedures for sample analysis
are* discussed in Section 2. 7. 2.
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Table 2-1 Phase Program Goals (Con't. )
Phase V GEOMET Response
At the completion of the effort prescribed here- GEOMET, with permission of EPA, demon-
inabove, the Contractor shall conduct a demon- strated the Prototype system and procedures
stration of the operation of the collection device to the Program Monitor at the GEOMET lab-
developed under this contract before the cogni- oratory in Pomona, California. (Section 2.7.5)
zant Project Officer at the National Environ-
mental Research Center, Research Triangle
Park, North Carolina 27711.
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2.3 HIGH-VOLUME AIR SAMPLER SELECTION
GEOMET purchased and has operated a Unico 550 Turbine-
Jet High-Volume Air Sampler (Environmental Science Division, Bendix
Corporation) throughout this program. The Unico was chosen due to
the simplicity of design of the sampler and of the sampler shelter.
The sampler is hung in the wooden shelter and supported by the
lower edge of the inlet ducting adaptor which contains the particulate
filter. A typical sampler of this configuration is shown in Figure 2-1.
The originally proposed concept was to place a collection plenum be-
tween the incoming air duct, and the sampler blower motor casing.
The Unico 550 lends itself quite suitably to this arrangement. The
plenum elongated the blower/ducting dimension, but does not affect the
sampler operation nor cause any modification to the sampler shelter.
The addition of the plenum to the Unico 550 is shown, in a conceptual
sketch, in Figure 2-2A.
GEOMET also owns a Precision Scientific Hi-Vol sampler,
which is offered with an optional aluminum shelter. While the shelter
for the Precision sampler is well built and durable, the sampler/
shelter combination requires modification to add the GEOMET collec-
tion plenum. This sampler is held in place by a notched shelf built
into the shelter. The Precision Hi-Vol contains a cast ring which is
an integral part of the sampler blower motor housing. The ring rests
on the shelf and supports the sampler within the shelter (Figure 2-2B).
With this particular unit, the collection plenum cannot be inserted into
the sampler system without either obviating the use of the shelter roof,
or lowering the shelter sampler support shelf to allow clearance for
the Prototype system.
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ExplodeJ vltw of typlc.l high-vclmr.* ซ!r Mnplir parti.
Figure 2-1. Assembled Sampler and Shelter.
2-13
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Sampler
Support
Shelf
A. Assembled Sampler and
Collection Plenum in
Wood Weather Shelter
GEOMET
Collection
Plenum
B. Precision Scientific
High-Volume Sampler
and Aluminum Shelter
Figure 2-2
Commercial Hi-Vol Sampler
2-14
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Two points are evident as a result of this discussion:
1} the Unico 550 sampler and shelter were well chosen for this pro-
gram, and 2) thought should be given to the varied configurations of
sampler shelters already in the field. It is assumed that some
standard will be set on High-Volume sampler configuration, or that
the simple modifications necessary to accept this Prototype instru-
mentation will be allowed.
2. 3.1 Hi-Vol Sampler Air Through-put Studies
The first work done with the Unico 550 Hi-Vol sampler
was to run preliminary studies on air through-put of collection
materials and collection canister configurations.
Various mesh sizes of charcoal and alumina were tested in
a cylindrical tube mounted in the annular throat of the Hi-Vol filter
adapter ducting. Barnebey-Cheney 6-10 mesh activated charcoal was
tested, as well as the following alumina material - Harshaw 0.125
inch diameter pellets, Alcoa 4-8 mesh and Alcoa 8-14 mesh granules.
It was determined that up to 3.75 inch bed depths of these materials
could be loaded in a 3. 0 inch average diameter tubular canister, and
a nominal value of 20 CFM could be easily pulled through the Hi-Vol
sampler. Later, up to seven inches of alumina (0.125" pellets) were
utilized with the Hi-Vol, including a fiberglass particulate filter, and
a nominal value of 20 CFM through the Hi-Vol was maintained.
Through-put studies were also made of a prototype canister
made of perforated stainless steel. A 400 gram batch of alumina
pellets ( -%^3. 50 inches deep in a 3.1 inch diameter canister) which
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had been tested in the Hi-Vol at 20 CFM, gave 35 CFM through-put
when transferred to the prototype perforated canister. These canis-
ters, containing eight 0. 062 holes per linear inch (64 per inch ) were
considered for final canister configurations wherein collection media
density or shape required large volumes of the collection material
and low residence time of the through-put sample air stream. These
early Hi-Vol tests outlined the magnitude of the amounts of adsor-
bents which could be used to collect mercurial vapors. The ultimate
sizing of the canister beds is discussed in Sections 2.6, 3.3 and 4.0.
2.4 MERCURY CHALLENGE SOURCES
In order to evaluate the interim design concepts and com-
ponents prior to the design of the Prototype system, methods of pro-
viding accurate amounts of the three forms of mercury were neces-
sary. These methods and/or apparatus required capability of supplying
mercury challenges to the collection system with known mercury con-
centrations and minimum loss. The minimization of loss was a very
important aspect of the total collection efficiency of the Prototype
system. A review of the challenge methods is presented in the follow-
ing sections.
2. 4.1 Particulate Mercury Challenge Sources
GEOMET utilized ultra-fine mesh mercuric oxide (HgO) and
mercuric sulfide (HgS) to challenge the collection efficiency and par-
ticle retention of the standard fiberglass Hi-Vol Sampler filter. All
runs on this program were made using the Reeve Angel 934-A12
(8" x 10") standard Hi-Vol filters. It was discovered early in the
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program that in order to provide even distribution of the challenge
material over the filter area, the mercuric compounds must be
mixed with some inert carrier. This was especially true at low
challenge levels wherein less than 1.0 /*gm of material was to be
used. To prevent as much loss of the challenge sample as possible,
the weighed aliquots of HgO or HgS were placed into 45 gram
batches of Cab-O-Sil, an inert fumed silica. This mixture was then
fed into the Hi-Vol sampler air stream and onto the filter. This
method was extremely successful for the application of particulate
challenges to the Prototype instrumentation system.
2.4.2 Elemental Mercury Vapor Source
Four separate source models were constructed in the
attempts to assemble a device for challenging prototype collection
canisters with elemental mercury, Early attempts were made to
devise a method for determination of mercury vapor emissions
through weight loss measurements. Considerations of the very
small amounts of mercury to be measured caused the abandonment
of this procedure. The ultimate method devised, which has been
completely successful, utilized air passage over heated liquid mer-
cury under controlled conditions. This apparatus is depicted in
Figure 2-3.
In operation, air is pumped through the sealed vapor
source system and passes over a small pool of liquid mercury.
Heating tape is used to heat the mercury held in the U-tube increas-
ing the mercury vapor pressure for high challenge levels. Voltages
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Vapor to Hi-Vol
for Challenges
Reference Temp.
Thermometer
Pyrex U-Tube
Containing Mercury)
0-12 1/min.
Flowmeter
Control Valve
Activated Charcoal
Air Filter
Air Inlet
Figure 2-3 Elemental Mercury Vapor Source
2-18
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from 0-60 VAC yield challenges of from 0.3 to >200yug/M (at
temperatures ranging from x^ZO C to ,*xl20 C). All data was taken
with air flow through the U-tube at 5 liters/minute, but both air flow
and temperature can be varied for a wide range of values. Testing
proved the success of this method in providing elemental mercury
vapor challenges over the complete spectrum of mercury levels re-
quired for quantitative testing under the scope of this program.
2. 4. 3 Organic Mercury Challenge Sources
Several challenge methods were evaluated for organic mer-
cury input sources during this program. Early attempts using com-
mercial mercury sources were unsuccessful. For example, a diethyl
mercury Dynacal permeation tube was acquired from Metronics Asso-
ciates. It was Certified to permeate at a rate of 264 -5% ng/minute
at 40ฐC. This special-order device was utilized in a Metronics heat
exchanger and tube holder, as depicted in Figure 2-4. Challenge
runs were attempted utilizing a 200 gm. collection canister filled
with sulfur treated (13%) activated charcoal. Permeation tube chal-
lenges at 40ฐC were monitored with a GEOMET Module 109 Catalytic
Converter in conjunction with the Model 103 M. A. M. It was rapidly
apparent that the permeation tube was releasing elemental mercury
vapor into the tests rather than diethyl mercury, exclusively. Appar-
ently, the diethyl mercury in the permeation tube was partially hydro-
lyzed or decomposed. For the purpose of testing adsorption on the
sulfur treated charcoal, this mixed source was not satisfactory. No
further testing was attempted with this prototype permeation tube.
2-19
-------
Figure 2-4
Technical Bulletin No. 7-70
DYNACAL* PERMEATION TUBES
APPLICATION NOTE ON THE TESTING AND CALIBRATING OF AIR ANALYZERS
Testing
An air analyzer can be quickly tested to see if it is "about right" by
placing a DYNACAL* permeation tube into the analyzer's inlet air stream.
One satisfactory test method is to put the DYNACAL* tube into a cylinder
such as a 20-cm glass drying tube and connect the lower end of the drying
tube to the analyzer inlet. Clean and empty gas absorbtion tubes (plastic)
work equally well. Temperature is obtained from a thermometer placed near
the inlet. Concentration is estimated using the DYNACAL* standard rates
for the particular temperature and tube length.
Calibrating
A DYNACAL* permeation tube and the Metronics specially constructed 2-
section glass apparatus can be used as shown below to provide a gas stream
of known concentration for dynamic calibration.
ntrt Connecting Tubing
(thortatpoMibl*
rf_ H /H /
Air
, InirHJMd Cut,
For Eoty ACCMI (I)
Thซrmomซtซ(4)
DYNACAL RMHONM
Tutt On Owmhwm S*{2)
high vokm. flow
UM fl COl I 0* COppflr
tubing upHnomXI)
-PnroMGfcmnoMl)
A SIMPLE CALIBRATIOH APPARATUS
Parts List
1. Heat exchanger and tube holder with with glass beads available from
Metronics. Model 4-15 holds 4 ea. 15-cm tube
Model 4-30 holds 4 ea. 30-cm tubes
2. DYNACAL* tubes available from Metronics.
HOW TO ORDER.
Please see other side for
3. Inlet filter similiar to GCA Chemical Cartridge and end-of-line holder
available from Mine Safety Appliance, 201 N. Braddock Ave., Pittsburgh,
PA 15208 is adequate for most purposes. Cylinders of zero-air or nitro-
gen are recommended where background contamination is significant.
4. Thermometer, high grade laboratory type of suitable range and gradua-
tion, is available from most laboratory supply companies.
5. Constant temperature bath can range from tap water bath (about 17ฐC in
our local system) to baths complete with precision temperature control-
lers such as those sold by Cole-Parmer, 7425 N. Oak Park Ave., Chicago,
111. 60648.
?ON|GS ASSOCIATES, INC. aaoi PO*TซR DRIVE ปTANFOIปO INDUSTRIAL MUK PALO AL.TO. cซuronปiiป
2-20
-------
Diluted die thy 1 mercury in CC1. was also briefly utilized
to assess the collection on sulfur-treated charcoal. However, again
decomposition or hydrolysis appeared to interfere. Utilizing the
Mercury Monitor separately and in conjunction with the Catalytic
Converter, it was estimated that the diethyl mercury had decom-
posed into a complex 47. 5% elemental mercury and 52. 5% (C_Hg)_
Hg. Reagent grade diphenyl mercury was also examined as a chal-
lenge material. However, the vapor pressure of this compound at
room temperature is too low to be effectively used. When the sam-
ple was heated, it sublimed. Condensation of the sublimed vapors
throughout the apparatus made quantitation impossible and left objec-
tionable contaminating residues.
A supply of dimethyl mercury was then obtained, and used
as the challenge form for organic mercury in tests throughout the
remainder of the program. The dimethyl mercury was held in sealed
containers, and diluted in 1-propanol to the required challenge concen-
tration immediately prior to each test run. The 1-propanol was
chosen due to its high boiling point (97. 2 C). The challenge mixtures
were applied to the Hi-Vol by placing the challenge mixture container
in the incoming air stream, and evaporating the mixture into the
Hi-Vol from a wick-feeder protruding from the container. The liquid
challenge volume was preset to be totally evaporated during the test
period. If there was a residual challenge volume, it was measured
as accurately as possible and subtracted from the anticipated calcu-
lated challenge level.
2-21
-------
2.4.4 Ambient Air Challenges
Some ambient level of elemental mercury was always pre-
sent during the test runs carried out during the program. Background
adjustments were made to compensate the collected data for this
effect.
At the end of the program, a final long duration ambient
air run was made utilizing the final Prototype collection system. In
this run, no "artificial" mercury challenge was added over the normal
mercury level found in the Pomona, California atmosphere. Results
of this test are presented in Section 2. 9. 7.
2.5 AIR TRAIN CHALLENGE APPARATUS
In order to facilitate near real-time measurements of mer-
cury vapor challenge levels, as well as obtain collection efficiency
data on collection canister configurations under test, it was decided
to utilize the GEOMET Model 103 MAM as an ancillary device within
the air train challenge system. The data collected with the M103 was
then used, in later recovery analysis runs, to correlate the calcu-
lated mercury challenges on collection canister absorbents. This data
was correlated directly with an atomic absorption spectrophotometer
(AAS) (Perkin-Elmer Model 303). The Model 103 was set up and
operated with the mercury vapor source described in Section 2. 4. 2
above. A part of the checkout procedure was a baseline calibration
of the instrument. A typical graph of that calibration is provided in
Figure 2-5. A sampling probe was installed to remove approximately
1 CFM of the air passing through the Hi-Vol sampler and supply that
2-22
-------
600
i 400
D
M-
rt-
05
200
hO
I
ro
Room Temp: 28 C
Date: 7/19/72
Hg Temp:
Grid: 012
Model 103 S/N 020
Figure 2-5 GEOMET Model 103 Instrument Calibration
250
Mercury (nanograms)
-------
Room Temp: 28 C
Date: 7/19/72
Hg Temp:
Grid: 012
Model 103 S/N 020
Figure 2-งk GEOMET Model 103 Instrument Calibration ';:!:::
tฑfatrttattt^|4J4lป^U44J4Um^^4t.44-;^{U-tlU.i!l-Ul4i.U .|UU,:..|.^;^r-,-t-rr:rhr?TTh--r rr^hrrTtrrrHrr::
250
-------
air sample to the Model 103. Following preliminary mercury chal-
lenge testing, it was found that the sensitivity of the Model 103
required dilution of the incoming sampled air to provide accurate and
reproducible readings at the higher mercury challenge levels. A
dilution step was added to the system and calibrated to determine
validity of incoming mercury challenge levels, background and over-
all test results when the diluter was in use. The sampling train then
in use is depicted in Figure 2-6.
An interim Hi-Vol sampling arrangement was instituted
wherein the Model 103 probe was positioned within the collection ple-
num to monitor collection efficiency of the absorbents during each
challenge run. A critical orifice, with pick-up connections for a
Magnehelic gage, was installed for monitoring air flow through the
stacked canister system. The details of this interim air sample
monitoring mode are provided in Figures 2-7 and 2-8. This new
method allowed positive control over air volumes passing through
the canister, which was critical to absorbent collection efficiency
data calculations. It was felt, however, that the Model 103 should
monitor the mercury challenge level rather than possible break-
through (loss of collection efficiency) in the absorbent canister system.
This decision was supported by the fact that no break-through had
occurred in any of the high level mercury challenge runs. Therefore,
the Model 103 canister sample output probe was sealed and reinstalled
on the Hi-Vol sampler exhaust downstream of the blower housing.
This final change to the collection plenum is shown in Figure 2-9.
2-24
-------
Air and Hg
Challenge
Inlet
Sample/
Air Mix
Plenum
Diverter Line (To Exhaust)
GEOMET
Model 103
MAM
0-36 1/min.
Flowmeter
Ag Filtered Room
Air Inlet
^Oj.2 1/min.
Flowmeter
Dilution
Flow Valve
Excess Sample
Air to Exhaust
Air Pump
CFM)
\
Model 103
Exhaust
Figure 2-6 Mercury In Air Sampling Train
2-25
-------
Canister
Sample
Output
Air Bypass Control
Ring
Mating Connection
'for Hi-Vol Sampler
Upper Ducting
Partial Outline of
Canister Position
'Auxiliary Sample Port
Canister Support
Critical Orifice Plate
Assembly
'Pick-Up Connections for
Magnahelic Gage
Mating Connection
for Hi-Vol
Sampler Blower
Figure 2-7
Canister Holder and Sampling Plenum for Hi-Vol Sampler
2-26
-------
Particulate Filter
Hi-Vol Duct
Sample Plenum
Canister Sample
Output
w
Upper Collection Canister
Air Bypass Control Ring
Lower Collection Canister
Canister Support
Magnahelic Gage
(Canister Air
Throughput)
'Critical Orifice Holder
Figure 2-8
Collection Canister/Hi-Vol Sampler Interface Configuration
2-27
-------
m.
Interim
Canister
Probe
Output
tv
i
ro
00
Final Collection Plenum Configuration
Figure 2-9
Calibrated Bypass Air Control Ring
Magnahelic Gage
Canister Monitor
Calibrated Total System CFM Gage
Air Sample Probe
(Hi-Vol Exhaust Position)
-------
During the latter part of this program, GEOMET decided
to miniaturize the entire Air Train Challenge Apparatus described
above (Ref. Figure 2-6). Flowmeters measuring in the ranges of
0-5 and 0-25 1pm were purchased and the entire dilution system was
mounted on the side of the Hi-Vol sampler shelter. All tubing con-
nections, including a column for silver-treated alumina pellets for
mercury-free dilution air, were converted to 316 stainless steel. A
positive pressure diaphragm pump was installed for precise control
of sample air from the Hi-Vol to the Model 103. This configuration
has created a simple and compact test arrangement which allows a
more convenient work package and portability of the test system.
The final apparatus is depicted in Figure 2-10.
2. 5.1 GEOMET Model 103 - Mercury Air Monitor
2. 5.1.1 General Description
The experimental measurements of mercury in air streams
utilized for controlled test purposes were obtained, in part, with the
GEOMET Model 103 Mercury Air Monitor. A schematic diagram of
the M103 is shown in Figure 2-11. This device was set to produce
an analysis every 3-6 minutes depending on the level of mercury in
the gas. For organic mercury compounds the Model 103 was coupled
with a Catalytic Converter (Module 109) which reduced all compounds
to elemental mercury for analysis (Figure 2-12).
The Model 103 operates on the principle illustrated in
Figure 2-11. Air is drawn into the instrument at pre-selectable flow
rates and sampling time cycles across a silver collection grid which
2-29
-------
Complete Prototype Instrumentation Assembled with Test Apparatus.
2-30
-------
Exhaust
Air_
Sample
Figure 2-11: Functional Diagram,
Model 103
Blower
[SJ
GEOMET
Cmlytic Converter
GEOMET Model
103 or 104
Mercury Air
Monitor
Figure 2-12: Model 103 with Catalytic Converter
-------
serves to concentrate the sample. Readout is achieved by use of
sequential heating of the two electrically independent grids sections.
During heating of the first section by direct passage of electrical
current through the silver wire, collected mercury is shifted to the
rear or second section. Adsorbed impurities or potential interfer-
ences, which are not strongly bound to silver, pass into the photo-
meter for quantitation. The signal, if any, is stored electronically
for subtraction from the signal resulting from heating the second grid
section. Heating of the second section releases the collected mer-
cury sample plus any collected interferences into the photometer for
quantitation. The readout procedure is automatically controlled, it
requires 70 seconds. The entire readout cycle requires 2.0 minutes.
At 70 seconds, the corrected peak signal voltage is displayed on a
digital voltmeter. Connections are provided for simultaneous use of
a printer or strip chart recorder. The collection, readout and data
presentation cycle is adjustable for continuous air monitoring over
long periods of time.
The schematic diagram of the electrical system is detailed
in Figure 2-13.
2. 5.1. 2 Improvements to Model 103
Field testing of the original Model 103 showed two weaknes-
ses: (1) instability in the UV source output was not detectable. This
caused poor reproducibility at low mercury levels, and required con-
stant vigilance to avoid variations from calibrated performance, and
(2) line power variations resulted in damage to the grid.
2-32
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O^2tHS>
DENOTES PIN IDe.M-IFIU.TiaU
2. Q DE.MOTIS -~lปE NUMBERS
TMI% sCMR.oซvric TO
IM&TRUUEMT S/M
*e.v e.
Figure 2-13
-------
Both problems have been eliminated by redesign: (1) an
automatic lamp intensity control has been added, and (2) an SCR
current control has been added to both grid circuits. The circuitry
involved is shown schematically in Figures 2-14 and 2-15. Other new
features include (a) a shutter, (b) Instrument Zero Adjustment and
(c) Span Adjustment.
2.5.1.3 Details of Changed Features
Automated UV Lamp Current Control
An automated UV lamp current control system is now
included in the Model 103 Mercury Air Monitor. This "loop" system
obviates the necessity for manual adjustment of the UV lamp, and
offers stable lamp conditions for the life of the bulb. This system
contains two functions:
1. "Sampling" error voltage control,
2. "Hold" error voltage control.
The purpose of the "Sampling" error voltage control is to maintain
the UV lamp intensity, measured at the photodiode, at a constant
level prior to the peak reading cycle. The "Hold" error voltage con-
trol maintains a fixed, but non-controlling, voltage to the lamp during
peak reading cycles.
On instrument start-up, the Model 103 Mercury Air Monitor
is set up ready for air sampling, the power switch is actuated to the
"ON" position and the instrument operation observed. The operator
then depresses the manual READ pushbutton. The purpose of this
action is to initially start the UV lamp, and therefore actuate the
2-34
-------
ฃ36 KZ5
+Z4V0C
-L/SVOC.
Figure 2-14: Recent
Improvements in Lamp
Controls and Adjustment.
UV
4UK.KCNT
U&ULAfTUL
/PC
Figure 2-15
Recent Improvements in Model 103 Grid Control
Circuitry.
-------
automated UV lamp current control system and instrument readout
cycle. The DVM readouts for the first fifteen minutes are considered
invalid due to the need for UV lamp stabilization.
Once the lamp is actuated by the first READ cycle, the
lamp voltage is automatically controlled. Current fed to the lamp
is monitored by a transistorized current leveling circuit. Should the
output voltage of the lamp (measured by the photodiode) vary above or
below the preset value (normally 9.85 -0.20 volts), the current is
automatically reduced or increased to maintain the desired value.
During the sample readout cycle, the control system shifts
to the "Hold" error voltage control system. Coincidental to the sample
signal being measured by the peak detectors, the variable voltage con-
trol is by-passed and the lamp is held at a constant level value and
not adjusted during the peak reading cycles. This provides a constant
unchanging baseline voltage over which the sample value is super-
imposed.
Following the sample readout, the lamp system returns to
the "Sampling" error voltage control mode. Here, the error voltage
control is used to sustain the UV lamp temperature and activation con-
currently with the use of a mechanical shutter positioned in front of
the photodiode. This condition maintains the lamp in a ready state,
and the shutter extends the life of the photodiode by cutting off UV
radiation from the lamp.
The shutter, which has been installed in front of the photo-
diode, remains in the closed position during the sample collection
2-36
-------
cycle. The shutter blade interrupts the passage of light from the UV
lamp to the photodiode. During the "Read" cycle the shutter is lifted
out of the light path and allows the full output of the lamp to reach
the photodiode. This action occurs prior to the entry of the air
sample into the photometer. The shutter is timed to close following
the readout cycle, again protecting the photodiode. The shutter has
increased the photodiode life to something greater than 30,000 read-
out cycles.
Instrument Zero Adjustment
This adjustment provides a method of evaluating any elec-
tronic "noise" within the Mercury Air Monitor, establishes that level
of noise and provides adjustment to compensate for that signal level
in the final readout value. This adjustment can be performed with
any amount of mercury in the sampled air passing through the system.
In operation, the Instrument Check Switch (located on the
rear instrument panel) is moved from the "Normal" position, UP to
the "Zero Chk" position. The "Read" button, on the front panel, is
then pushed to activate the readout cycle. During the Peak 2 portion
of the cycle, the Zero Knob (located on the front instrument panel) is
adjusted to maintain a reading of +000, or any other desired positive
value. At this point, the Instrument Check Switch should be returned
to the "Normal" position.
This action has now calibrated the instrument for full elec-
tronic zero, including the collection grid firing cycle. The Instru-
ment Zero Adjustment should be made following any replacement of
collection grid assemblies, and as often as operational use requires.
2-37
-------
Span Adjustment
The Span Adjustment is used to calibrate the Mercury Air
Monitor upper limit readout. The instrument zero point is adjusted
with the Instrument Zero Adjustment, and the Span Adjustment is
then necessary for full instrument calibration. The span is adjusted
prior to shipment and generally is not readjusted by the instrument
user. A procedure for changing the span is included in the Opera-
tions Manual. An additional use of the Span Adjustment is for
matching the sensitivities of two or more Mercury Air Monitors
being concurrently utilized for air sampling so that the same mer-
cury vapor level injected into all instruments yield the same final
reading on all instruments.
Grid Temperature Control
It has been observed that full line voltage is not required
by the grids for desorption of collected mercury. By installation of
SCR current controls, the grid current is limited to a maximum of
15 amperes. Previously an upper limit of approximately 30 amperes
was obtained. Chronologically, since this limitation was imposed on
the silver grids, no single grid failure has been noted in more than
4000 hours of operation.
2-38
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2.6 MERCURY ABSORBENT DEVELOPMENT
This section of the program Final Report is devoted to
discussions of the development of unique and efficient collection
materials for the three forms of mercury - particulate, elemental
and organic. Rationale for approaches utilized for each material
type is provided.
2.6.1 Selection of Adsorbents
The following remarks form the rationale for selection of
the silver on alumina adsorbent utilized as a major candidate for the
collection medium for elemental mercury and for charcoal as the
collector of organic mercury:
Adsorption of elemental mercury and its compounds from
the gas phase onto solids is largely a surface phenomenon. The
amount of adsorbate, its rate of adsorption and the efficiency of mer-
cury extraction from the gas are dependent on the specific surface
and the total surface of the adsorbent which is presented in the pro-
cess. Other factors which control the removal capacity include the
nature of the adsorbent and adsorbate, the geometrical state of the
adsorbent, the temperature and velocity of the air, the concentration
of the mercury-containing gas, effects of other gases in the stream
and the proportion of the adsorbent surface covered as the adsorbate
collides with the surface. In general, the adsorbent bed operates
efficiently until the total capacity of the bed is approached.
2-39
-------
Desirable adsorbent properties include:
(a) Capacity: 15-30% of adsorbent weight,
(b) Low resistance to gas flow,
(c) Inertness,
(d) Resistance to deterioration during use,
(e) Regenerability, and
(f) Provide ready recovery of adsorbate for analysis.
The adsorption of elemental mercury is most efficiently
achieved on the noble elements, gold, silver and platinum where the
chemisorptive mechanism resembles amalgamation. Selection among
these metals has largely been made on the basis of economics:
silver is vastly less expensive. Thin layers of gold on supports have
been utilized (References 1-7) but regenerability of very thin films is
usually poor. Also, both gold and platinum tend to hold onto small
portions of mercury tenaciously if present in reasonable mass. The
recovery of elemental mercury from silver is completed at rela-
tively low temperatures.
Reference 1: S. H. Williston and M. H. Morris; U.S. Patent
3,173,016 (1965); and S. H. Williston; U. S. Patent
3,178,572 (1965)
Reference 2: W. W. Vaughn and J. H. McCarthy; U.S. Geological
Survey Prof. Paper pp D123-127 (1964).
Reference 3: S. H. Williston; Jour, of Geophys. Res, 73, 7051
(1968).
2-40
-------
Reference 4: D. H. Anderson, J.H. Evans, J. J. Murphy and
W.W. White; Anal. Chem. 43, 1511 (1971).
Reference 5: L. M. Azzaria; Canadian Geolog. Survey Paper
No. 66-54, pp 13-26 (1967).
Reference 6: J. J. McNerney and P. R. Buseck; Science 178,
(10 November, 1972) 611 (1972).
Reference 7: NTIS Report No. PB-210 817. TraDet, Inc.
Columbus, Ohio (1972).
2-41
-------
Typical surface areas for various adsorbents and adsorb-
ent supports are shown in the following table:
Specific Surface Area
Support (m^/g)
Pyrex Wool (Corning, No. 3940 0.27
Glass Fiber (Fiberglas, various) 0.04 - 0.16
Activated Alumina (Harshaw, A1-0104T) 80 - 100
Activated Alumina (Alcoa) 100 - 350
Activated Charcoal
(Barnebey-Cheney, TCA) 1000
Activated Carbon (Darco) 612 - 1190
Activated Carbon (PCC) 1100
Activated Carbon (Nuchar) 750
Silica Gel (Davison) 400 - 800
Silica Gel (Monsanto) 520
Attapulgus Clays -^120
Bentonite (Filtrol) 280
Fuller's Earth (Floridin) 124
Silica-Alumina (various) 500 - 600
Activated Magnesia (Westvaco) 30 - 230
Ranges are presented where more than one product is available.
Surface areas may be varied by modification of preparational tech-
7
niques. For example, activated carbon may be made with a 10 m /g
surface area by heating at 2750ฐC. Steam and heat treatments may
be used to reduce the surface areas of all silicate structures.
Calculated on basis of average fiber diameter and density.
2-42
-------
On this basis the following data show the surface areas
utilizable in the collection canisters (160 ml) with normal packing:
Average Total
Specific Packing Wt. in Surface
Surface Area Density Canister Area
Support (m2/g) (g/ml) (140 ml)(g) (m^) Ratio
Pyrex Wool
Alumina (Harshaw)
Activated Carbon
0.27
100
1000
0.065
1.09
0.54
9.1
160
75
2.5
16, 000
75,000
1.0
6,400
30,000
(Barneby-Cheney, TCA)
These data show that utilization of a nonporous solid such as pyrex
wool will minimize the total surface available for adsorption of mer-
cury. (With careful packing the glass fiber content of a canister might
be doubled.) The useful surface with alumina is about 6,400 times
greater than that obtained by pyrex wool; activated carbon offers
<** 30, 000-fold more surface.
While the useful surface of the supports is reduced after
deposition of silver, particularly at the relatively high levels used in
these collection experiments, the Ag/Al_0, preparations employed still
offer approximately three (3) orders of magnitude more surface than
would glass wool preparations in the same volume. Charcoal, used
for collection of the organic mercury compounds is one of the highest
surface area adsorbents in common usage.
The objective of the foregoing comparison is to indicate the
advantages accruing by use of a Ag/Al_0, preparation for collection
of elemental mercury. It meets most of the criteria indicated in the
2-43
-------
initial paragraph of this section: good capacity, low resistance to
gas flow, inertness, resistance to deterioration during use, regenera-
bility, easy recovery of mercury for analysis and relatively economi-
cal initial costs. Other adsorbents apparently do not meet all of
these criteria as conveniently. However, several other compositions
should be examined in order to obtain a maximal collection technique.
Two in particular, gold and silver on pyrex wool should be tested
further. However, in order to overcome the obvious advantages of
silver on a porous support, these would have to be at least 1000
times more efficient in capture of mercury vapor (atoms)' than is
silver on alumina.
2. 6. 2 Particulate Mercury Collector
During the progress of this program, GEOMET has utilized
the standard glass fiber particulate filters normally employed in con-
junction with Hi-Vol samplers. These Reeve Angel 934 AH glass
fiber filters were used exclusively and gave no evidence of collected
sample loss with proper handling. A unique method was devised
for analysis of the mercury collected on these filters (See Section
2.8.2.), and no problems with the filters were evident in the recovery/
analysis method. It is assumed that any glass fiber filter, with the
same basic specifications, may be utilized to collect mercury and be
amenable to the recovery /analysis method.
2.6.3 Elemental Mercury Adsorbents
At the onset of the program, GEOMET decided to manufac-
ture trial lots of silver-treated alumina in order to evaluate the feasi-
2-44
-------
bility of this adsorbent type as a collector for only elemental
mercury.
Several preliminary batches of silver-treated alumina were
prepared with AgNO, from samples of 0.125 alumina pellets (Harshaw,
2
Surface Area: 80-100 m /g), and 4-8 and 8-16 mesh alumina granules
(irregular shapes). These batches contained 2-5% Ag by weight.
Volumes of these prototype mercury collection substrates were tested
in tubular canisters (3" diameter) placed inside the Hi-Vol sample
ducting upstream of the Hi-Vol blower motor. Challenges utilized the
system described above.
Challenge Level,
Collection Substrate Bed Depth yu^ Hg/M3 Collection Eff., %
0.125 Alumina 3.0" (300 gm) 44 64%
Pellets
4-8 Mesh Alumina 3.0" (350 gm) 48 96%
Granules
0.125 Alumina 5.0" (710 gm) 230 >99%
Pellets
0.125 Alumina 6.0" (855 gm) 230 ^99.7%
Pellets
0.125 Alumina 7.0" (1,000 gm) 230 >99. 99%
Pellets
2-45
-------
These test results indicated that the pellets were very
efficient in collecting mercury vapor especially in bed depths of 7. 0
inches even at extremely high mercury challenge levels. Also, the
Hi-Vol sampler maintained ^20 CFM air through-put at this maxi-
mum bed depth. Quantities of Ag-treated 8-14 mesh alumina were
tested early in the reporting period, but did not give the desired
results due to (1) decreased air through-put through the Hi-Vol
sampler (^20 CFM), and (2) lower collection efficiencies than the
4-8 mesh alumina granules.
Twenty-four (24) hour collection efficiency runs were made
on several GEOMET -prepared batches of one-eighth inch alumina
pellets treated with silver. For example, one batch contained silver
coating averaging 3. 5% by weight. This 1, 000 gm. pellet batch was
challenged with a constant "medium" level of mercury (3.3yug/M )
for 24 hours. The collection efficiency of this material ranged from
an initial value of 99. 3% to a low of 94. 5% at the conclusion of the
run. The result of this test was compared to similar tests run on
pelletized alumina coated with.** 6% silver by weight. Eight hundred
gm. of this material was also subjected to a 24-hour test with a
2
challenge level of mercury vapor at 3.3 ^ug/M . The same 800 gm.
batch was then challenged with a "high" level stream of elemental
mercury vapor at a constant concentration of 100 ^ug/M . This latter
level is stipulated in the Statement of Work as the maximum threshold
limit for collection. This GEOMET-prepared product gave collection
efficiency ranges of 99.2 to 92.6% with the 3.3 ^ug/M challenge,
2-46
-------
3
and 99.9 to 99.3% with the 100 ug/M mercury challenge. Figure 2-16
presents the results of these preliminary three 24-hour runs.
During the program progress, it became evident that the high
efficiency of the silver -treated alumina would allow a Prototype system
elemental canister size of .^xZOO ml or 180 gm of treated pellets. Pre-
paration of the GEOMET silver -treated adsorbent was refined until
the pellets contained 5 12% silver by weight. Here, a 50/50 (w/v) so-
lution of AgNO- and distilled water was applied to untreated 1/8 inch
diameter by 1/8 inch long cylindrical alumina pellets (Harshaw Chemi-
cal Company, Catalyst AL-0104, Lot 61) under vacuum. Following full
wetting of the alumina support, the pellets were dried overnight at
100ฐC. The pellets were then placed in a muffle furnace and heated
at 600ฐC for two hours to drive off residual nitric acid. The pellets
were then ready to use as adsorbent in elemental mercury collection
canister. These particular pellets have shown typical collection effici-
3
encies of 100 percent at 3.8 ^ag/M for 24 hours and 97.1 percent at
28 Mg Hg/M for 24 hours. The preparation steps have been even
further simplified to allow preparation of 1 kilo of treated pellets to be
made in less than one hour. This time excludes oven drying of the
AgNO, on the pellets, and subsequent firing of the pellets in the resis-
tance furnace to remove the residual nitric acid. These preparations
provide excellent collection efficiency and material balance (Ref. Sec-
tion 2.9.2 and have been reclaimed for possible reuse by additional
heating in a resistance furnace combined with circulated air to remove
the bulk of collected mercury on the first reclaiming cycle. GEOMET
2-47
-------
1O X 1O TO THE CENTIMETER 46 1513
IO X 25 CM ซDf I* US.*.
100
99
Silver @ 100 fig Hg/M
2-5% Silver @ 3. 3 PR Hg /M
6% Silver @ 3. 3 pg Hg/M
12
Time, Hours
-------
feels that silver treatment of alumina could be converted, with some
attendant processing equipment, to an economical commercial pro-
cess.
To fully appreciate the rationale that GEOMET utilized in
selection of silver-treated alumina pellets over more widely publi-
cized methods, the data presented above in Section 2.6.1 (Ref. 1)
*
should be considered in conjunction with U. S. Patent No. 3,178, 572 ;
column 6, lines 15 through 60:
"The mercury-absorption chambers 71 and 82
contain highly effective absorption media for the
specific removal of mercury from the flowing air
as compared with any other contents of the air.
Useful for this purpose is glass wool having its
fibers coated with pure gold. A coating of silver
may also be used but this is not as desirable as
gold because of its susceptibility to formation of
silver sulphide under the action' of hydrogen sul-
phide content of the air, though it may be used
in sulphur-free and chlorine-free atmospheres.
Other metals which are characterized by wettabil-
ity by a/id some solubility in mercury may be
used, but none has been found to be more effec-
tive than gold. The gold may be deposited on
the glass wool by ordinary and convenient depo-
sition methods, for example by merely wetting
the wool with a gold salt, such as chloride, and
decomposing the salt by heat for deposition of
the gold. There may be used, in place of glass
wool, nickel wool on which the gold is deposited
in the same fashion or by precipitation by the
nickel from a solution of a gold salt. A difficulty
with glass wool is that glass will absorb, to some
extent, mercury, and consequently the dummy
chamber 94, containing the same amount of glass
wool but uncoated, will be required to be satur-
ULTRA-VIOLET RADIATION ABSORPTION ANALYSIS APPARATUS
FOR THE DETECTION OF MERCURY VAPOR IN A GAS.
Samuel H. Williston, Los Altos, Calif., assignor to Cordero Mining
Company, Palo Alto, Calif., a corporation of Nevada
Filed May 17, 1963, Ser. No. 281,088
6 Claims. (Cl. 250-43.5)
2-49
-------
ated to the extent of this absorption before use.
In the case of nickel, however, the absorption
of mercury is negligible. Other carriers of
gold or silver may also be used, such as alum-
ina, completely coated to prevent absorption of
water. The general properties of the carrier
should be that of a physical form to present a
maximum absorbing surface of the noble metal
per unit volume, reasonably low resistance to
flow, adhesion to its absorbent coating and non-
destructible by heat used to drive off mercury.
In itself, it should be non-absorptive of mer-
cury, or a least exhibit uniform absorption
thereof. The last property may be best des-
cribed by saying that the carrier should be non-
wettable by mercury. It should, so as to be
usable in the dummy chamber, be non-absorptive
of other substances which absorb the radiation
bands absorbed by mercury. The noble metal
coating on the carrier should be very thin,
ranging from a small fraction of a thousandth
of an inch to not more than a few thousandths.
The reason for the latter limitation is that if a
thick coating of gold, for example, is used, the
absorbed mercury will diffuse deeply thereinto
and will not be driven off completely in regen-
eration of the absorbent by heat at moderate
temperatures."
GEOMET's selection of alumina over glass wool was basically due
to the gross differences in available surface area for mercury col-
lection (Ref. Section 2.6.1, Page 2-42). The choice of silver
rather than gold, as a noble metal mercury collector, markedly
reduces the cost of the final alumina adsorbent. As previously
reported, it appears that this product would be commercially pro-
duced easily and economically.
2-50
-------
2.6.3.1 Commercially Available Silver-Treated Adsorbents
During the program effort, commercially available silver-
treated alumina and molecular sieve material was purchased from
W. R. Grace Company (Davison Chemical Division); Strem Chemicals,
Incorporated; and Coast Engineering Laboratory.
The Grace product, designated as SMR 7-4215, was stated
to contain 7. 5% silver deposited on 4-8 mesh alumina granules. This
material was tested twice. The first test was carried out in pre-
paration for a 24-hour efficiency test i. e., it followed all standard
background measurements, etc. taken on the GEOMET sampling train.
A canister containing 910 gm. of this material failed, however, to
remove 0. 8 yUgm. of mercury vapor contained in a 30 second pulse.
The collection efficiency was 0% with this. challenge duration and level.
The Grace product was then subjected to heat treatment in a muffle
furnace where it was held for two hours at 500ฐC. When 42 gms. of
this material was subjected to the output of the GEOMET Hg vapor
source (a standard screening procedure) at 42ฐC, it absorbed the ele-
mental mercury vapor challenge well enough to warrant the heat
treating of a 910 gm. batch of granules. This batch was prepared
and entered the 24-hour testing cycle but again failed a 30 second
pulse of mercury heated to 42ฐC (0.8 ^ugm.).
The Strem material, Lot 837-S, contains 11% silver by weight
on alumina pellets with 0.5 M2/gm. surface area. A 42 gm. aliquot
of this material was subjected to mercury vapor at 42ฐC from the
GEOMET Hg vapor source and collected no calculable amount of mer-
2-51
-------
cury. An equivalent aliquot was heat treated at about 1,000 C for
one hour and then challenged by the GEOMET vapor source for
12 hours. Inasmuch as this was a lengthy screening test, no Model
103 data were collected during this period of time, during which the
collection efficiency dropped from ^99% to 0% and the exact time of
collection efficiency loss is not known. A mass of 900 gms. of this
material was then heat treated at 1,000 C and rerun at this volume
and weight in a 24-hour collection test. The treatment did not
enhance the collection efficiency.
GEOMET purchased 300 gms. of Silver X, Type 13X,
12-16 mesh, chromatographic grade molecular sieve material (Coast
Engineering Laboratory). This compound is the result of an exchange
process wherein the sodium in the Zeolite has been completely
exchanged by silver. The sieve was subjected to bench-scale mer-
cury collection tests, and subsequently two 100 gram batches were
included in total system collection efficiency tests (Test data table
Section 2. 9.1). Both runs gave very poor results, insofar as the
material balance was no greater than 57. 7%. Some difficulty was
found in removal of the collected mercury with the recovery/analysis
technique. It is felt that this was due, in part, to the initial recov-
ery furnace configuration (Reference Section 2. 7. 4. Also, the internal
structure of the Silver X may preclude easy recovery of absorbed
mercury (Ref. Patent 3,178,572 above). Due to the short duration of
the program, and the excellent results of the GEOMET-prepared
silver-treated alumina, no further effort was expended on this particu-
2-52
-------
ular mercury adsorbent. It does, however, have considerable
promise as a collection medium.
2.6.4 Organic Mercury Absorbents
Many tests were carried out to evaluate the collection
capability and recovery characteristics of commercially available
charcoals to be used for organic mercury vapor collection. Three
types of charcoals were evaluated: (1) Silver Impregnated (10% Ag
by wt.} Charcoal, lot 841S, 4-8 mesh, Strem Chemicals, Inc. ,
(2) Sulfur-Treated (12%) Charcoal, CB-1786, 4-8 mesh, Barnebey-
Cheney, and (3) Activated Charcoal, TCA, 4-8 mesh, Barnebey-
Cheney. All three charcoals were initially bench-tested for mer-
cury collection and recovery characteristics. The Strem material
collection efficiency was approximately 35% that of either the sulfur
treated or TCA activated charcoals. The Strem material was there-
fore eliminated from further consideration as a program candidate.
The Sulfur -Treated (12%) Charcoal (CB-1786) collected
within approximately 85% of the TCA activated charcoal. The results
of tests for evaluation of mercury recovery indicated problems with
the utilization of sulfur-treated product, however. This charcoal
was found to liberate an apparent heavy hydrocarbon-like material
when heated in the mercury recovery resistance furnace. The im-
purity appeared to come out of the vapor state, downstream of the
furnace, and it coated the interior surfaces of the transport tubing
ahead of the iodine monochloride collection bubblers. This residue
trapped some of the mercury vapor being transported to the bubblers,
2-53
-------
and therefore severely affected the mercury recovery and material
balance results of these tests. This phenomenon justified the elimina-
tion of the sulfur-treated charcoal from further consideration as a
useful organic mercury collector.
GEOMET then utilized 75 gm aliquots of Barnebey-Cheney
TCA activated charcoal for all organic mercury collections. This
absorbent volume, without any special loading or packing procedures,
occupies approximately the same volume ( s^lbQ ml) in the proposed
Prototype collection canister as does the 180 gms of silver-treated
pellets utilized for elemental mercury collection. The collection
efficiency and mercury recovery from the TCA charcoal was excellent,
and was reported as the final GEOMET choice for organic mercury
absorbent utilized in the Prototype instrumentation.
2.7 PROTOTYPE COLLECTION SYSTEM
The various developmental details of the total Prototype
system are discussed throughout this program Final Report. The
details of the final configuration are included here, including fabri-
cation sketches of each component.
2. 7.1 General
The design of the Prototype system has been kept uncom-
plicated to offer minimum development costs and maximum opera-
tional characteristics. The materials of construction, e. g. 6061T6
aluminum, 316 stainless steel, PVC plastics, etc., are free from
mercury upon purchase. These materials are utilized in areas to
2-54
-------
obviate the unnecessary contamination by mercury forms, and where
the possibility of low mercury background might occur, methods have
been devised for readily cleaning all component surfaces.
The Prototype system consists of 1) a Hi-Vol sampler
collection plenum, 2) two absorbent canisters, 3) an air through-put
control ring, 4) absorbent materials (Ref. Section 2.6), 5) an air
metering system, and 6) a Unico 550 Turbine Jet High-Volume
Sampler with a wooden shelter.
Attendant testing devices include an elemental mercury vapor
source (Ref. Section 2. 4. 2), a GEOMET Model 103 Mercury Air Moni-
tor (and a M109 Catalytic Converter Module) for tracking mercury
challenge levels, and a Processing System for the recovery and quan-
titative analysis of mercury from particulate, elemental and compound
vapors, respectively. (Reference Section 2. 8).
2. 7. 2 Hi-Vol Collection Plenum
The major component of the Prototype collection system is
the Collection Plenum which is inserted between the Hi-Vol blower
motor housing and the adaptor ducting. The plenum is attached with
standard threaded screw rings which fit commercially available Hi-
Vol samplers. Without the canisters, the plenum contains canister
supports, a removable calibrated air bypass control ring, and a cali-
brated orifice plate for the monitoring of canister air through-put.
There are feed-through connections, from the orifice plate, through
the plenum wall for the attachment of a Magnehelic pressure gage.
A drawing of the assembled system is provided in Fig. 2-17, and a
photograph of the unit in Fig. 2-18. Fabrication drawings are pro-
vided in Figures 2-19 through 2-27.
2-55
-------
8 Inches
6 Inches
26
Inches
12 Inches
<&0
Calibrated Bypass Air Control Ring
Magnahelic Gage
Canister Monitor
Calibrated Total System CFM Gage
Figure 2.1?
Hi-Vol Collection Plenum Installed in Place
2-56
-------
Figure 2-18
Collection Plenum and Canister Assembled onto Hi-Vol Sampler
2-57
-------
Air Bypass Control
Ring
Mating Connection
'for Hi-Vol Sampler
Upper Ducting
Partial Outline of
Canister Position
Canister Support
Critical Orifice Plate
Assembly
Pick-Up Connections for
Magnahelic Gage
Connection
for Hi-Vol
Sampler Blower
Figure 2-19
Hi-Vol Collection Plenum
2-58
-------
.\-ZSV\IM_L.
I
U1
vO
Figure 2-ZO
-------
Figure 2-21
KJO,
2-60
-------
4:2.50-e> TWD
Figure 2-2Z
N/OO\1=-.
NO.
BY '
H . H ,
O IS
-------
FUUSH
t\ป
N
Figure 2-23
-------
D\A. X IVZO DV,
Figure 2-24
2-63
-------
Z.,\-2.5
-.500
Figure 2-25
'. U0\o\-Tlo
\OJ-ZAlT2-
2-64
-------
\ O --
X \.oVo~DP,
y r^ ' ir *LT
^"1 ~~_ . ^^^_^^^_^__
TV4 "D ,
Figure 2-26
"TUSH
SI
10
2-65
<5fflHR>
-------
Figure 2-27
\-bAo
JIT.
2-66
-------
2. 7. 3 Collection Canister Design
The physical characteristics of the Prototype system
canisters were established as a result of extensive studies of Hi-Vol
air transport characteristics, mercury collection material surface
area and packing parameters, and evaluation of the wide range of
mercury levels which must be collected and recovered in analysis.
The canisters were scaled down from a 1000 gm volume to 180 grams
(/v 160 ml) of adsorbent for elemental mercury collection, and a like
volume containing 75 grams of absorbent for organic mercury col-
lection. These canister volumes, at ซv 20% air through-put of the
Hi-Vol total at 20 CFM, provide the ability to collect and analyze
over the entire collection range from a few nanograms of mercury
to 100,000 is ng/M as stipulated in the contract Statement of Work.
The canisters will be utilized for mercury collection,
sample transport and storage and are therefore to be light weight
and durable. PVC plastic canisters are well suited for this use,
and heavier more expensive materials of construction (e.g. stainless
steel) were therefore unwarranted. The canister bodies, screen
closures and plugs are recyclable, and easily cleaned for reuse. A
drawing depicting the assembly of the canisters within the Hi-Vol
plenum is provided in Figure 2-28.
The design for the prototype collection canisters is pro-
vided in Figures 2-29 through 2-31. The canister bodies are fabri-
cated from sections of plastic tubing and closures which retain the
absorbents are held in place by a close-tolerance friction fit. The
Type "A" end closures, Figure 2-29, are fabricated with a captive
2-67
-------
screen section which prevents absorbent loss yet allows air sample
through-put. The center dividing closure, Type "B" configuration,
is fabricated by joining together parts of two Type "A" closures.
This minimizes the number of special fittings and decreases tooling
and fabrication costs. The canisters may be easily emptied and
refilled in the field, or shipped intact in plastic shipping containers
back to a central laboratory for analysis and recycling.
2-68
-------
Hi-Vol Duct
Hi-Vol Plenum
Particulate Filter
Sffi
Upper Collection Canister
Air Bypass Control Ring
Lower Collection Canister
Canister Support
Magnahelic Gage
(Canister Air
Throughput)
Critical Orifice Holder
Figure 2-28
Collection Canister/Hi-Vol Sampler. Prototype
Interface Configuration
2-69
-------
5. 5 Inches
5. 5 Inches
-Type "A" End Closure
1. 75 Inches
-Typical Thin-Wall Plastic Tubing
-Type "B" Multiple-Use Closure
-Type "A" End Closure
Figure 2-29
Prototype Multiple-Use Collection Canisters
2-70
-------
N
1
5.50
1
Figure Z-30
BOOV
-------
.002
\.T50
"DIA.
\.1AO
T5\/V
(s?foc.vO
.001 _^
\ 5-0
Figure 2-31
2-72
ซEDIEป
-------
2. 7. 4 Recovery Analysis System
The processing method is fully described in Section 2. 8,
and with the exception of the recovery furnace is non-deliverable
under the contract. The recovery furnace consists of (1) a furnace
insert, which is used for holding absorbents within the furnace, and
(2) a heavy duty crucible furnace capable of heating samples in the
range of 0-2000ฐF.
The aliquots of absorbents are placed in a modified crucible
and attached to a support fixture which is lowered into the crucible
furnace. The support fixture has been designed to direct a stream
of transport air through the heated collection material and carry off
the liberated mercury to a series of EPA-type liquid collection bub-
blers containing iodine monochloride solution. A detailed assembly
drawing and fabrication sketches are provided in Figures 2-32
through 2-38.
2. 7. 5 Demonstration to EPA Program Monitor
Phase V, of the contract Statement of Work, required that
GEOMET conduct a demonstration of the operation of the Prototype
collection device before the cognizant Project Officer at the National
Environmental Research Center, Research Triangle Park, North
Carolina.
In light of the attendant processing equipment, recalibration
procedures and nature of the collection device, the cognizant Project
Officer was invited to witness a demonstration of the Prototype
instrumentation at the laboratory of the GEOMET Office of Experi-
2-73
-------
mental Development in Pomona, California. On Tuesday,
20 February, 1973, Miss Eva Wittgenstein, Program Project Officer
(EPA Laboratory Measurements Research Section, Chemistry and
Physics Laboratory), reviewed the development effort on the program
and witnessed an operational demonstration of the Prototype instru-
mentation.
2-74
-------
t
Furnace Cover
To EPA-type
Bubbler
Train
Sample Vapor
Outlet Tube
(Collect)
Outlet Tube
(Crucible Support
Tubing)
Quick-Release
Pin for change
of sample
crucibles.
Support Disc
Insulation
Crucible
Furnace
Body
Heated Furnace
Cavity
Crucible Lid
"Cover
Metal Crucible
Air Inlet Slits
Figure 2-32
Recovery Crucible
Furnace Details
2-75
-------
OS) I 7? SO B.C.,
C.OVE.R
MAT. '.
NO.
ORES
Figure 2-33
"DRAVNM
2-76
-------
NO.
Figure 2-34
2-77
-------
as
ts>
i
K10.
-------
CO
MO
Figure 2-36
. VA .
-------
SEOMETTJMC.
J7.S
Figure 2-37
A-
2-80
-------
.B HOUES
.OA-O
KIO.
Figure 2-38
2-81
BY*.
-------
2.8 RECOVERY ANALYSIS PROCEDURES
GEOMET was charged with the responsibility of providing
both a "removal" and "transfer" step as necessary in quantitative
recovery and analysis of all three forms of mercury. The following
sections describe the development of this methodology and attendant
equipment.
2. 8.1 Recovery System Description
The recovery system for the Prototype mercury collection
instrumentation was initially the same for all three forms of collected
mercury. It was based on a furnace and bubbler technique. As the
program progressed, it became apparent that the elemental mercury
adsorbent and organic mercury absorbent could be handled by this
method, but a better procedure was developed for particulate mer-
cury recovery from the glass fiber filter.
The final system, referring first to the adsorbent (silver-
treated alumina for elemental mercury vapor) and the absorbent
(activated charcoal for organic mercury forms) is shown in Figures
2-39 and 2-40. The mercury sources feed elemental and organic
mercury forms to the Hi-Vol sampler. A portion of the total air
stream is metered through the canisters where the two forms of
mercury are selectively collected. Following the collection cycle,
the two canisters are emptied into storage containers, labeled and
sealed. A ten (10) percent aliquot of the adsorbent is weighed out
for processing. An equal amount of the original adsorbent, which
was not used in the collection cycle, is placed into the resistance
2-82
-------
00
Hg
Source
GEOMET
M103
M. A. M.
t
^"^y /
M
S
<
ixing and
Aliquot
eparation
Aliquot
Collection
Hi-Vol Sampler Adsorbent
and
Collection Canisters
Furnace
Insert
Vapor
^^
Resistance
Furnace
I
^k-
L^
1
EPA Collection Bubbler Train
Collected
Liquid
Sample
Figure 2-39 Mercury Challenge Collection Method
-------
Serial
Dilution
Aliquot
t\>
i
oo
Collected
Liquid
Sample
Liquid
Vapor
Silica Gel Bed
Gold
Plug
Induction
Furnace
Vapor
AAS
AAS
Recorder
Diluted
Sample
Moisture
Trap
10% Sodium
Borohydride
Solution
Figure 2-40. Analytical Method
-------
furnace for processing as an analytical blank sample. Samples are
held in a nickel alloy crucible which is lowered into the vertical
furnace cavity. The furnace has been pre-heated to a controlled
range of from 500ฐ to 700ฐC. The crucible holder is ducted to a
EPA-type collection bubbler (iodine monochloride) train and vacuum
source. (Ref. Fig 2-39) All furnace and bubbler train components,
except the crucible, are of stainless steel or Pyrex glass. Following
a thirty (30) minute collection cycle, the sample blank and sample
bubbler collection fluid is processed through the second half of the
processing apparatus. The sample, serially diluted as necessary,
is processed using a modified version of Method 2. Determination of
Mercury in Gaseous Emissions From Stationary Sources. Federal
Register, Vol. 36, No. 234, 7/12/72, Page 23250. Here, the
released mercury is pumped onto a gold wire plug in an Induction
Furnace and recollected. The I. F. is then fired and the mercury
passes through an Atomic Adsorption Spectrophotometer (AAS). The
recovery and analysis process is now complete. This method was
used for all alumina and charcoal absorbent processing throughout the
program. Certain modifications and refinements were made to this
system. A discussion of those refinements and the improved method
for processing the particulate filters is presented below.
2. 8. 2 Analysis of Particulate Mercury Samples
The first trial analysis of particulate glass filters, con-
taining mercury challenges, were carried out with the resistance
furnace approach as utilized for the absorbents as described above.
2-85
CEO,.
-------
A method was devised to fold the filters, on removal from the
Hi-Vol sampler following collection, in order to maintain sample
integrity and avoid any sample loss. This portion of the processing
technique is still valid. There did appear, however, to be some
difficulty in obtaining reproducible air flow through the folded filters
when they were placed in the recovery furnace for pyrolysis. There-
fore, a better and simpler method of analysis processing was devel-
oped and tested. The glass filters were folded into a compact
bundle (xvl" square x 1/2" thick) and placed into a wide-mouthed
inert plastic jar containing 100 ml of IC1 (iodine monochloride) solu-
tion. Several 3mm glass beads were added and the jar was tightly
capped. The container was then vigorously shaken so that the beads
maserated the filter. The mixture was allowed to stand overnight
to insure adequate mercury takeup by the IC1 solution. Aliquots of
the mixture were then centrifuged to separate the filter metrix from
the IC1 solution. Portions of the IC1 were serially diluted as neces-
sary and analyzed through the AAS for recovered mercury. This
procedure could be simplified by use of automated shaking devices,
or sonic separators in future development of the total Prototype sys-
tem. However, for the glass fiber filters it works adequately.
2.8.3 Analysis of Adsorbent Pellets
Initial mercury recovery runs, utilizing silver-treated
alumina adsorbents for elemental mercury, were made by placing
the pellets in an open cylinder positioned in the resistance furnace.
Transport air was pulled from the furnace to the EPA-type, iodine-
2-86
-------
monochloride collection bubblers through stainless steel tubing.
These preliminary tests indicate that 790% of the mercury was
released when the furnace reached a temperature of >^.350ฐC. This
release was in the form of a rather large "pulse" and tail-off of
mercury vapor was still in evidence when the furnace reached 505ฐC.
This phenomenon was< due in part to thermal gradients found in
heating the mercury-laden alumina adsorbent, and to the construction
details of the furnace tube. A cast iron tube was then used as a
replacement for the alloy steel liner. This alteration, while nega-
ting any apparent problems with mercury vapor hold-up during the
absorbent heating procedures, still lacked the necessary handling
convenience necessary for rapid laboratory analyses. A conceptual
design for the final Prototype system was reported to EPA, and that
design is provide in Figure 2-41. This exact design was never fully
completed. Instead, a less complicated design was formulated
(Reference Section 2. 7.4 above) and utilized on the remainder of the
program. This furnace insert method allowed the use of a standard
tube furnace and obviated the need for a cast iron or other metallic
furnace cover liner. The need for a human engineered handling sys-
tem was very important to the success of the adsorbent recovery
procedure.
The analytical procedure for recovery of mercury from the
absorbent pellets began by removal of the pellets from the collection
canister. The pellets should be transferred to plastic shipping/
storage containers, sealed and labeled. At time of analysis, the
adsorbent should be well mixed to achieve uniform mixing of the
2-87
-------
Sample Output
Probe
Air Inlet
Iron Furnace Cap
Removal Framework
Iron Furnace Liner
Sample Cup
Resistance Furnace
Elements
Temperature Gage
Figure 2-41
Conceptual Mercury Recovery Resistance Furnace
2-88
-------
mercury load throughout the adsorbent lot. The final Prototype
system canister design holds 180 grams of the silver-treated alumina.
A 10% aliquot is weighed out and placed into a cold crucible, assem-
bled onto the furnace insert, and placed within the pre-heated resis-
tance furnace ( ป,600-700ฐC) and connected to the EPA collection
bubbler train. Air is drawn through the pellet bed and into the
bubbler tain for 30 minutes. This has proven to be sufficient time
to heat the adsorbent and transport all the elemental mercury into
the liquid (IC1) collection bubblers. The 45 ml bubbler volume is
collected in clear glass storage bottles and transfered to the proces-
sing apparatus described in Section 2.8.1, above.
Refinements were made over the duration of analytical runs
made during this program. The tubing from the furnace to the EPA-
type collection bubbler train was reduced to a minimum to prevent
any fallout of mercury being transported to the bubblers.
Extremely high AAS readouts were occasionally experienced
when firing the collected mercury (from the samples obtained out of
the recovery process furnace bubblers) off the noble metal wire plug
in the induction furnace. In one or two instances, this phenomenon
occurred during the recheck of bubbler and pellet blanks. In order
to circumvent the possibility of elemental mercury vapor induced by
external or other laboratory procedures from interfering with ongoing
AAS readouts of critical test runs, two additional bubblers were
installed in the vapor transport tubing. The first of these contains
approximately 10 ml of a ฃ.10% sodium borohydride solution and is
2-89
-------
located immediately before the sample bubblers containing the alka-
line hydroxylamine solution used in this modified Hatch and Ott pro-
cedure. The second is a spray trap. It was found that apparently
some portions of the reducing solution used in the analytical method
pass into the tubing to the induction furnace from the bubblers. The
air stream transports droplets which line the passages and subse-
quently trap elemental mercury vapor. This mercury source appar-
ently causes intermittent, inexplicable signals in the AAS. The
additional sodium borohydride bubbler scrubs off any interferences
and droplets, but allows the passage of mercury vapor to the AAS.
The second bubbler is used completely empty. It acts as a spray
trap and as additional protection for moisture removal from the
sample air stream. The basic sample recovery and analytical method
utilizing the resistance furnace, modified Hatch and Ott procedure,
modified analytical method, induction furnace and AAS was fully suc-
cessful in processing the silver-treated alumina mercury adsorbent,
and the activated charcoal mercury absorbent.
2. 8. 4 Analysis of Charcoal Absorbent
The activated charcoal used to absorb inorganic and organo-
metallic mercury vapors was analyzed in the same manner as the
adsorbent pellets. This method was both practical, from a technical
point of view, and economical. It allowed the same equipment devel-
oped for the processing and analysis of the pellets to be used for the
activated charcoal. The only minor difference in the procedure was
that the total charge per canister of charcoal was 75 grams rather
2-90
-------
than 180 grams. The difference in the weight, of course, is due to
the densities and packing characteristics of the two different mater-
ials. The charcoal was also processed in 10% aliquots in the resis-
tance furnace, and the collected mercury passed through the GEOMET
processing equipment.
2. 8. 5 Other Analysis Methods
Due to the modification of processing technique for the
particulate filters, it seemed appropriate to examine the IC1 "soaking"
technique for both the silver-treated alumina adsorbent and the acti-
vated charcoal absorbent.
The leeching of mercury from activated charcoal by the
IC1 solution was not feasible. Bench studies indicated a chemical
reaction between the two constituents, and the release of large quanti-
ties of iodine. This reaction precludes the use of IC1 as a method
for chemical removal of the mercury from this absorbent. Other
chemical reagents should be evaluated as part of a liquid/solid sys-
tem for processing of the activated charcoal absorbent by a similar
extraction method.
The results from application of IC1 to the silver-treated
alumina appeared to be more favorable. Trial batches of the alumina
were given 30-360 minute soaks in IC1, and this solution was run
through the GEOMET processing train. Recovery of elemental mer-
cury appeared low ( ^ 50% of collected load) initially, but the method
did appear to operate properly with the alumina substrate. Due to
the short duration of the program, this potential change was not fully
2-91
-------
examined. Future evaluation should be carried out with IC1 and/or
other chemical oxidants/extraction solutions compatible with both the
alumina and the activated charcoal absorbent.
2. 8. 6 Additional Analysis Equipment
The GEOMET processing system for recovery and analysis
of all three forms of mercury is fully described in Sections 2. 8. 2,
2. 8. 3 and 2. 8. 4 above. The contract Statement of Work stipulates
that other types of equipment suitable for this processing be provided
in this report. In order to provide this information with some clar-
ity, the GEOMET processing system can be divided into segments
which may then have substitutions of equipment as necessary. The
various segments are shown below. Circled numbers in the schema-
tic diagram correspond to entries in the '"System Segment and Com-
ponent" column of the following table:
Furnace Insert Uj
I
Resistance
(Combustion)
Furnace @
I
Flowmeter (4j
Aspirator
EPA-type Bubblers 3J
I
Flowmeter
Atomic
Adsorption
Spectrophpto-
meter (8
*
Process
Bubblers
(ฃ)
H. F. Induction
Furnace
Vacuum Pump
2-92
-------
These segments, and commercially available equivalents,
are listed below to aid EPA and the Government in procurement
activities.
System Segment
and Component
Type
Additional Sources or
Substitution Instrumentation
ฉ
FURNACE INSERT GEOMET, Inc.
2] RESISTANCE
(COMBUSTION)
CRUCIBLE
FURNACE
3) COLLECTION
BUBBLERS
4] FLOWMETER
5) ASPIRATOR, VAC-
UUM PUMP
PROCESS
BUBBLERS
Lindberg, Type
56312-A
SOLA Basic Ind.
Watertown, Wise.
(EPA Design)
WEST-GLASS Corp.
12440 Exline St.
El Monte, Ca. 91732
Gilmont, Size 12
(0-2 1pm)
Roger Gilmont
Inst's, Inc.
161 Great Neck Rd.
Great Neck, N. Y.
11021
1) Any qualified machine
shop.
1) BLUE-M Electric Co.
138th & Chatham
Blue Island, 111. 60406
1) ACE Glass, Inc.
P. O. Box 688
Vineland, N. J.
1) FLORATER Flowmeters,
Matheson Scientific Co.
1850 Greenleaf Ave.
Chicago, 111. 60007
2) Dwyer VISI-FLOAT Series
Dwyer Instruments, Inc.
P.O. Box 373
Michigan City, Indiana
46360
Nalge #6140 1) AIRJECTOR
Nalgene Labware Div. Fisher Scientific Co.
Sybron Corp.
Rochester, N. Y.
14602
711 Forbes Ave.
Pittsburgh, Pa. 15219
(EPA Design)
2) CHAPMAN Model, and
RICHARD'S Model
Aspirators
Matheson Scientific Co.
(4-1, above)
1) Reference 3-1, above.
2-93
-------
Con't.
System Segment
and Component
Type
Additional Sources or
Substitution Instrumentation
ฉ
7) HIGH FREQUENCY
INDUCTION
FURNACE
8 ) ATOMIC
ABSORPTION
SPECTROPHOTO-
METER
ฎ
FLOWMETER
,10) VACUUM PUMP
Single Tube, LECO
Model 521-000
LECO (Laboratory
Equip. , Co. )
Hilltop Rd. and
Leco Ave.
St. Joseph, Mich.
49085
Model 303
PERKIN-ELMER
Corp.
Main Avenue
Norwalk, Conn.
06856
Gilmont, Size 13
(0-12 1pm)
Neptune DYNA-
PUMP (0-14 1pm)
Universal Elect. Co.
Owosso, Mich.
1) ECCO High Freq. Co.
7034 Kennedy Blvd.
No. Berger, N. J. 07049
1) Beckman Model 979
Beckman Instruments
2500 Harbor Blvd.
Fullerton, Ca. 92634
2) Janell-Ash ATOMSORB;
DIAL-ATOM 11; and
Model 800
Fisher Scientific
(5 - 1, above)
3) IL Model 353
Instrumentation Lab-
oratory, Inc.
113 Hartwell Ave.
Laxington, Mass. 02173
4) Corning Model 240
Corning Glass Works
Corning, N. Y. 14830
1) Ref. 4 - 1, 2 above.
1) Cole-Parmer Inst. Co.
7425 No. Oak Park Ave.
Chicago, 111. 60648
2) Thomas Industries
1419 Illinois Ave.
Sheboygan, Wis. 53081
2-94
-------
Con't.
SPECIAL NOTES:
Substitution couW be made for items
ฉป ฎ ฎ and ฎ bV com
available Mercury Analyzers.
1) GEOMET Model 103
GEOMET, Incorporated
2814-A Metropolitan PI.
Pomona, Ca. 91767
2) OLIN Mercury Monitor -
Liquids or Gas Module
OLIN Custom Analytical
Inst's.
120 Long Ridge Rd.
Stamford, Conn. 06904
Substitution could bernade for the
AAS system, Item @ with commer-
cially available photometer systems.
1) Coleman Mercury Analyzer
Model MAS-50
Coleman Inst's. Div. ,
PERKIN-ELMER Corp.
42 Madison St.
Maywood, 111. 60153
2) Mercury Monitor
Laboratory Data Control Co.
Interstate Industrial Park
Riviera Beach, Fla. 33404
3) Model 2006IL Mercometer
Anti-Pollution Technology Corp
937 So. Washington Ave.
Holland, Mich. 49423
2-95
-------
2.9 PROTOTYPE SYSTEM TEST DATA
The development methods utilized during the program to
obtain a uniform test procedure were oriented to establish a system
which would collect the three forms of mercury efficiently for a
minimum of twenty-four (24) hours. In addition, bench testing of
sample aliquots of absorbents, as well as challenge sources, was
used often and with great success. The purpose of this section is
to present data obtained on tests which were ^24 hours in duration.
The full Prototype system was challenged with all forms of
mercury from standardized sources (Ref. Section 2.4, above). All
combinations of challenges were used, i. e. elemental, elemental and
organic, the latter combination plus particulate mercury, and finally
an ambient air test for Hg in the atmosphere. The tests with lab-
oratory controlled challenges utilized all sources of mercury at levels
-2 3
from 4. 5 x 10 to 118 ^ปg/M . The ambient air run analysis showed
-2 3
a total collected level of 4. 1 x 10 /ซg/M of elemental mercury
averaged over the 25+ hour period. One hour data during this test
3
varied from 12 to 145 nanograms per M .
2.9.1 Collection Efficiency Tests
As previously stated, all trial absorbents were bench tested,
and monitored by the GEOMET Model 103, to ascertain break-through
limitations at various bed depths with variable challenge levels of mer-
cury. This method of testing was used to screen candidate absorb-
ents. Preparational methods and individual sample batches, using the
formulation selected as superior (12% Ag/Al-0.), were also checked.
2-96
-------
Four (4) of the first five of the twenty-four tests were monitored by
the Model 103 at the canister exhaust to check for mercury break-
through. The brief table below indicated the results of these tests.
Run No. Test Time, Min. Elem. Hg. Cone. Collection Efficiency
R2-07
R3-08
R4-09
R5-10
1440 (24 hrs. )
1599
1440
1440
3.8/,g/M3
28 ^ug/M3
9 ^g/M3
46 yfeg/M3
100%
97.1%
99. 96%
99. 79%
Average 99. 2%
At the end of the period in which tese data were obtained, the silver-
treated ( ,*, 12%) alumina pellet preparation had been evaluated and
adsorbent performance was reproducible. Therefore, it was concluded
that the adsorbent pellet collection efficiency was never less than 99. 2%
and approached 100%. All future testing was done with the Model 103
utilized for monitoring the Hi-Vol exhaust (downstream of the canis-
ters and Hi-Vol blower motor) in order to quantitate the actual chal-
lenge level.
Identical procedures were used in establishing the collection
efficiency for dimethyl mercury of the Barnebey-Cheney TCA activated
charcoal. After a series of bench tests in which dimethyl mercury
was undetectable in the downstream gas exhausted from small charcoal
canisters by use of the Model 103 in conjunction with a Converter Mod -
ule, no further measurements were made. Thereafter the collection
efficiency was assumed to approach 100%.
2-97
-------
The following table is representative of all the 24-hour test
runs carried out on the program. It includes the contaminant chal-
lenge tests (Runs R19-26 through R22-29), and the ambient air test,
Run R23-30. Following the table, Section 2.9.2 presents the analysis
of the ambient air test in detail. A discussion of the scatter found
in the analysis of pellet samples is included there.
On the basis of the analysis of the entire ambient air test
held in 10 batches it was shown that a standard deviation of -25% is
to be expected for an average of ten results. Thus, the material
balances obtained for the single results tabulated in Table 2-2 seem
reasonable with one or two exceptions.
It is apparent that the major problem involved in achieving
reproducible material balances which consistantly approach 100%,
relates to sampling the absorbents. When the entire absorbent bed
was tested, as in the case of the ambient air test, excellent recov-
eries were obtainable. Use of 10% aliquots of the solid adsorbent
requires very uniform homogenization of the sample. Since about
90% of the mercury is contained on 10-20% of the total sample, it is
particularly difficult to obtain representative samples especially when
dealing with 1/8" pellets. This problem is resolvable by using the
entire solid sample or a larger fraction such as 50%. Minimization
of the adsorbent bed volume would assist in facilitating this solution.
However the latter adjustment must be compatible with the range of
space velocities (volumes of gas/volume of adsorbent per hour) which
are acceptable. In general space velocities of the order of 50,000
2-98
-------
(vol/vol) per hour have been employed. The upper limit of the range
over which this may be acceptably varied is unknown. However, lower
values may be employed provided that an absolute quantity of mercury
sufficient to satisfy the threshold sensitivity of the analytical method
is collected. Further experimentation is recommended.
2-99
-------
Table 2-2
PROTOTYPE SYSTEM TEST DATA
Run Number
R2-07
R3-08
R4-09
R5-10
Hi-Vol Air Sampling Rate
Particulate Mercury Concentra-
tion (Expressed as Elemental Hg)
40 CFM 44 CFM
(1.13 M3/Min) (1. 245 M3/Min)
40 CFM
(1. 13 M3/Min)
40 CFM
(1. 13 M3/Min)
Elemental Hg Vapor
Concentration
Organic Mercury Concentration
(Expressed as Elemental Hg)
Sampling Time
Canister Sampling Rate
Vapor Analysis Rate
Analytical Interval
Material Balance
3.8 yUg/M"3 28
1,440 Min.
3. 56 CFM
(8. 9%)
1. 0 1pm
3. 9 Min.
62. 5%
1,590 Min.
4. 78 CFM
10. 9%)
1. 0 1pm
3. 9 Min.
100. 5%
1,440 Min.
4. 93 CFM
(12. 2%)
1. 0 1pm
3. 9 Min.
90%
1,440 Min.
4. 73 CFM
(11. 8%)
1. 0 1pm
3. 9 Min.
81%
-------
PROTOTYPE SYSTEM TEST DATA (Con't. )
Run Number
R6-11
R7-12
R8-13
R9-14
Hi-Vol Air Sampling Rate 25 CFM 23 CFM
(0. 71M3/Min) (0. 65M3/Min)
Particulate Mercury Concentra-
tion (Expressed as Elemental Hg)
Elemental Hg Vapor
Concentration
Organic Mercury Concentration mercury.
(Expressed as Elemental Hg)
Sampling Time
Canister Sampling Rate
Vapor Analysis Rate
ro Analytical Interval
i
o
t->
Material Balance
23 CFM 23 CFM
(0.65M3/Min) (0. 65M3/Min)
TEST
ONLY, pre-
liminary tests with combina-
tion of elemental and organic
mercury.
1,165 Min.
4. 85 CFM
(19. 4%)
1. 0 1pm
3. 9 Min.
N/A
1,460 Min.
4. 55 CFM
(19. 8%)
1. 0 1pm
3. 9 Min.
N/A
TEST
ONLY
Organic
Mercury
960 Min.
5.1 CFM
(22. 2%)
1. 0 1pm
3.0 Min.
N/A
TEST
ONLY
High Level
Elemental
960 Min.
5. 2 CFM
(22. 6%)
1. 0 1pm
3.9 Min.
N/A
-------
PROTOTYPE SYSTEM TEST DATA (Con't. )
Run Number
R10-15
Rll-16
R1Z-17
R13-18
Hi-Vol Air Sampling Rate
tv>
I
H->
o
Particulate Mercury Concentra-
tion (Expressed as Elemental Hg)
Elemental Hg Vapor
Concentration
Organic Mercury Concentration
(Expressed as Elemental Hg)
Sampling Time
Canister Sampling Rate
Vapor Analysis Rate
Analytical Interval
Material Balance
LAB TESTS ONLY
Improved Recovery Proce-
dures.
20 CFM 15 CFM
(0. 57M3 /Min) (0. 42M3 /Min)
0.33
0.4
118
1,440 Min.
4.65 CFM
(23.8%)
4. 0 1pm
3.0 Min.
86%
Avg.
4. 25 mg
1.92
0.6
1,440 Min.
3. 46 CFM
(23. 2%)
4. 0 1pm
3.0 Min.
98. 5%
Avg.
-------
PROTOTYPE SYSTEM TEST DATA (Con't. )
Run Number
R14-19
R15-20
RS13X-21
R16-22
Hi-Vol Sampling Rate
22 CFM 22 CFM
(0.62M3/Min) (0.62M3/Min)
Particulate Mercury Concentra-
tion (Expressed as Elemental Hg) 92.2 mg* 8.6 mg#
Elemental Hg Vapor
Concentration
Organic Mercury Concentration
(Expressed as Elemental Hg)
69.1 /ig/M"* 53.3
16.0 zig/M3 7.3
19 CFM 22. 5 CFM
(0. 54M3 /Min) (0. 64M3 /Min)
--0--
--0--
4. 4/ug/M** 4.
2. 6 ^xg/M3 6. 7xlO~4,ซซ_g/M3*
Sampling Time
1, 440 Min. 1, 410 Min.
1,020 Min.
1,380 Min.
Canister Sampling Rate
Vapor Analysis Rate
Analytical Interval
4. 80 CFM
(21. 9%)
0 . 16 1pm
3. 6 Min.
5. 36 CFM
(24. 4%)
0. 17 1pm
3. 6 Min.
3. 62 CFM
(19. 0%)
4. 0 1pm
3. 0 Min.
4.88 CFM
(21. 7%)
36 1pm
6. 0 Min.
tN)
,L Material Balance
o
u>
148%
91. 5%
57. 5%**
Sample Contaminated.
* Calculated
** Molecular Sieve Run
-------
PROTOTYPE SYSTEM TEST DATA (Con't)
Run Number
R17-23
R18-24
RS13X-25
R19-26 (I)
Hi-Vol Air Sampling Rate
21. 5 CFM 20 CFM
(0.61 M3/Min) (0.57 M3/Min)
Particulate Mercury Concentra-
tion (Expressed as Elemental Hg) 0
Elemental Hg Vapor
Concentration
Organic Mercury Concentration
(Expressed as Elemental Hg)
Sampling Time
Canister Sampling Rate
Vapor Analysis Rate
Analytical Interval
to Material Balance
i
o
"^ Added Contaminants /Concentration
5. 22 CFM
(24. 3%)
36 1pm
6. 0 Min.
126%
4. 31 mg*
2.0 ^g/M3 78
0. 57 ^Mg/M 6. 7
1,548 Min. 1,350 Min.
4. 95 CFM
(24. 7%)
2 1pm
3. 6 Min.
90%
19 CFM 21 CFM
(0.54 M /Min) (0.59 M /Min)
14. 23 mg*
90
12. 2
1,470 Min.
3.68 CFM
(19. 4%)
1. 9 1pm
3.6 Min.
46. 5%**
2.
435 Min.
4.82 CFM
(23.0%)
4 1pm
3.0 Min.
99. 9%
Chlorophenol (0. 5 ppm)
(19. 5 ppm)
*Calculated; **Molecular Sieve Run; (I) Interference Test
-------
PROTOTYPE SYSTEM TEST DATA (Con't. )
Run Number
R20-27 (I)
R21-28 (I)
R22-29 (I)
R23-30 (A)
Hi-Vol Air Sampling Rate
22 CFM 20. 5 CFM
(0.56 M3/Min) (0.56 M3/Min)
ZZ CFM Z3 CFM,
(0.56 M3/Min) (0.65 M^/Min)
Particulate Mercury Concentra-
tion (Expressed as Elemental Hg) 0
Elemental Hg Vapor
Concentration
Organic Mercury Concentration
(Expressed as Elemental Hg)
Sampling Time
Canister Sampling Rate
Vapor Analysis Rate
Analytical Interval
Material Balance
i- Added Contaminants /Concentration NO gas
i
H
O
___0---
6. 1 y6tg /M
0^*5 Mm O /\J[
ซ"''' Af ft / *vi
1,015 Min.
5.02 CFM
(24. 0%)
2 1pm
3. 0 Min.
87. 5%
NO gas
(I. 6 nnm^
---0---
8.4 yUg/M3
067 4. or /M"
" ' WCA B ' *
1,015 Min.
5.02 CFM
(24. 0%)
2 1pm
3. 0 Min.
70. 0%
SOz gas
11. 7 nnm^
..-0---
8. 0 yUg/M
1 Q ปm a /T\A
' jvL5 ' "^
947 Min.
4. 86 CFM
(22.1%)
2 1pm
3. 0 Min.
53. 5%
H_S gas
ITT. "5 T-mml
---0---
4. 1 x 10"2
1, 540 Min.
4. 74 CFM
(20.6%)
82 1pm
6. 0 Min.
98. 8%
(I) Interference Test
(A) Ambient Air Test
-------
2. 9. 2 Ambient Air Monitoring for Elemental Mercury
As a check of the performance of the method of mercury
collection and analysis utilizing the canisters and accessories as
developed during the contract, an ambient air test for elemental
mercury was carried out from the roof of the Pomona Laboratory.
The apparatus was set up as previously described
(Section 2. 5 and 2. 7). The air sample from out-of-doors was ducted
through a three inch (i. d.) flexible stainless sttel tube to the mani-
fold at the top of the Hi-Vol Sampler. The GEOMET Model 103 was
connected, as previously, to the exhaust from the plenum section of
the Hi-Vol assembly.
The ambient air test was carried out for 25 hours and
40 minutes (1540 minutes) with 180g of Ag./Al203 pellets in the canis-
ter used for elemental mercury collection. The pellets utilized were
those which had proved superior in previous testing, Harshaw alumina
Grade A1-0104T impregnated with 12% silver. The preparational method
has been described in Secbion 2.6.3. The GEOMET Model 103 was
operated on a 6-minute cycle with 257 analyses automatically obtained
and printed during the course of the experiment. The following table
shows the conditions and the Model 103 results.
Conditions
Test Duration 1540 min.
Hi-Vol Sampling Rate 651 1pm
Canister Sampling Rate 134 1pm (20.6% of total)
Model 103 Sampling Rate 82 1pm
2-106
-------
Test Results from GEOMET Model 103
Number of Analyses 257 .
High Hourly Value (10 analyses/hr) 145 ng/m -hr.
Low Hourly Value (10 analyses/hr) 12 ng/m^-hr.
Average Value (25+ hours) 41 ng/m^
Tables 2-3 and 2-4 show the individual results obtained
with the Model 103; Figure 2-42 shows the applicable calibration.
After mixing by rolling and quartering methods, the 180 g
canister sample of pellets was separated into ten batches of 18 g of
pellets each. These were analyzed by the techniques indicated in
Section 2.8.3. In general, a 5.0 ml aliquot of the 45 ml iodine
monochloride absorbent was used in the reduction step. The results
were obtained by use of a Perkin-Elmer -Model 303 atomic adsorption
spectrophotometer. Calibration of this instrument is shown in
Figure 2-43.
2-107
-------
000004'4
0 U 0 0 0 4 5
0000046
0000048
0000047
0000052
0000055
0 U 0 0 0 5 4
0000048
0 0 0 0 C 5_6_
0 0 0 C C 5 6
0000051
0000053
0000059
0000059
0000074
0 0 0 0 0 8 6
Time 2015 Hours, 2/26/73
0000
0000
0000
0000
0000
0000
0000
0000224
000023 1
000023 1
0000255
0000252
0 0 0 0 2J5
0 0 0 0 2*8 2
0000284
0000284
00003 1 1
0000303
0000304
00003 1 1
0000335
0000378
0000 185
1 1
1 1
3,
3*5
63
89
89
Numbers in right hand
margin are averages
of DVM readings for
ten previous printouts.
Time 1615 Hours, 2/26/73
Table 2-3
Analysis on Ambient Air Test
GEOMET Model 103
Air Sampling Rate 82 1/m
Read Results Upward from Bottom to Top
2-108
-------
j u o o j > y
0000039
0000037
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J 0 0 0 0 3 2
00003 3_6_
0 u 0 0 0 3 7
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C000036
0000039
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0 0 0 U 0 4JJ_
0 'J 0 U 0 4 0
OG00039
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0 'j 0 U 0 3 5
0000040
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U.JO 00-3 f-
0 000040
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0 0 C 0 0 4 3
0 U 0 0 0 4 3
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0 U 0 0 0 4 6
0000033
0000033
000004 2
Time 0051 Hours, 2/27/73
Time 2015 Hours, 2/26/73
2-109
-------
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0 0 0 U 0
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0 0 0 0 0
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Time 0509 Hours, 2/27/73
If
Time 0051 Hours, 2/27/73
2-110
-------
0000035
0000032
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0 0 0 0 0 2^5_
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0 C 0 0 0 3 3
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OU0003 1
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0 0 0 0 0 2 6
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Time 0945 Hours, 2/27/73
v
Time 0509 Hours, 2/27/73
2-111
-------
0000209
000022 1
0000223
0000223
0000211'
0000194
0 U 0 0 1
OGOO 1 9 1
00002 1 5
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000022 5
OU002 1 4
0000222
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00002 I 3
0000203
Time 1357 Hours 2/27/73
OOOG
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3 1
25
"2
22
00
fit
-v
Time 0945 Hours, 2/27/73
2-112
-------
00001 1.0
oooo i i o
0000 1 05
0000100
0000 1 1 5
0000 1 1 8
0000 1 29
oooo iT5
0000 1 38
OOOO 129
OOOO 1 37
OOOO 1 37
0000 I 40
OOOO 1 5 1
OOOO 1 68
OOOO 1 77
OOOO 1JJ
OOOO173
OOOO 1 7 1
OOOO I 59
OOOO 1 59
OOOO 1 28
0000128
0000168
OOOO 166
OOOO 1 66
OOOO 1
OOOO I 75
OOOO I 80'
OOOO 18 1
OOOO 18 1
OOOO I 92
C 0 0 0 1 8 9
OOOO 18 1
OOOO 1 85
OOOO 1 85
0 0 0 0 1 7_6
OOOO 1 69
OOOO 1 9 1
0000220
Time 1755 Hours, 2/27/73
1
Time 1357 Hours, 2/27/73
2-113
-------
Table 2-4
Atmospheric Test .,,
GEOMET Model 103 Data"
Started 1615 hrs., 2/26/73
R eading
(DVM divs)
298
215
79
50
43
39
37
38
35
35
37
34
34
32
33
27
31
34
77
154
Analysis
(ng/m3)
145
99
33
20
18
16
15
16
15
15
15
15
15
14
14
12
14
15
32
67
Time
(hrs. , midpoint)
1645
1745
1845
1945
2045
2145
2245
2345
0045 (2/27)
0145
0245
0345
0445
0545
0645
0745
0845
0945
1045
1145
*Each reading represents an average of 10 readings.
2-114
-------
Table 2-4 (Con't.)
Reading
(DVM divs)
214
206
182
159
148
112 (7 readings)
Analysis
(ng/m3)
99
94
82
70
64
48
Time
(hrs., midpoint)
1245
1345
1445
1545
1645
1706
2-115
-------
DVM Units
500
:t
llHIMn&i-miiii
400
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-) ปป<
300
200
**
O,
100
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Figure 2-4S
ration of Perkin Elmer Model 303
>mic Adsorption Spectrophotometer
Mercury (nanograms)
vs.
Chart Divisions (Peak)
libration Date 3/1/73
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100 110 120 130
2-117
-------
The results for the ten portions of the adsorbent are
shown in Table 2-5. As is apparent from the average air concentra-
tions calculated from both methods and the total amounts of mercury
as analyzed by both methods, the High-Vol canister procedure and
the GEOMET 103, closely correspond. The canister procedure showed
+ 3
an average air concentration of 40. 9 - 10.5 ng/m . A simple stan-
dard deviation cannot be calculated for the GEOMET data since the
concentration of mercury in the air sample changes with time.
However, the standard deviation associated with the ten
determinations of the canister sample indicates a need for improve-
ment. The 25.6% standard deviation indicates that mixing and samp-
ling of the 180 g adsorbent bed has not been adequately achieved. Two
alternatives seem appropriate: (1) the adsorbent bed size should be
reduced so that (2) a relatively large fraction (or all) of the adsorb-
ent may be used in the recovery analysis. As a third choice a more
rigorous procedure for mixing the solid sample may be instituted.
However since a very large fraction of the total mercury is retained
at the top of the adsorbent, particles from the first layer will always
have a disproportionate effect on an analysis. Thus, it would be pre-
ferable to analyze the entire adsorbent sample
2-118
-------
Table 2-5
Ambient Air Test, Canister Method.
Analysis of Silver/Alumina Adsorbent
Sample No. Total Hg Collected
(ng)
1 1260
2 720
3 783
756 Average
3 Replicate 729
4 567
585 Average
4 Replicate 603
5 666
6 810
7 1008
8 945
9 774
10 927
Total 8451 nanograms
Average 845
Deviations
(ng)
415
125
62
116
278
242
179
35
163
100
71
82
1868
186.8
(a.d.)(22%)
Air Sampled 206.4 m
3 + 3
Average-Air Concentration 40.9 ng/m - 10.5 (o~) ng/m
Standard Deviation of Total 216 (25. 6%)
Mean Deviation of Total 187 (22.1%)
2-119
-------
Section 3. 0
CONCLUSIONS, RECOMMENDATIONS
AND COMMERCIAL PRICE ESTIMATES
-------
Section 3. 0
CONCLUSIONS, RECOMMENDATIONS
AND COMMERCIAL PRICE ESTIMATES
3.1 SUMMARY
During the course of the program a prototype device for
the quantitative collection of airborne mercury in particulate, elemen-
tal and combined forms, respectively, was designed, fabricated and
tested. The device utilized a Hi-Vol Sampler into which two canisters
containing absorbers for elemental and combined mercury were added
in a collection plenum below the glass fiber filter. The plenum was
located between the funnel-shaped inlet duct of the Hi-Vol Sampler and
the blower motor. It supports the two collection canisters and controls
the air flow through the series arrangement. Of the total air (20+ CFM),
about 1/5 passes through the canisters.
Particulate collection was tested with mercuric oxide and sul-
fide on the glass fiber filter; elemental mercury vapor was collected
on a silver-alumina adsorbent; dimethyl mercury was collected on the
activated charcoal phase.
As evaluated, the preferred configuration of the first canis-
ter contained 180 g (160 ml) of 12% silver on alumina (Harshaw, A1-0104T)
in a 1. 56" (i. d.) x 5.5" cyclinder. This adsorber removed 99.9+% of
the elemental mercury passed through in air samples. The second can-
ister (same dimensions) utilized 75 g (160 ml) of activated charcoal
(Barnebey-Cheney, TCA grade). It removed all combined mercury
from the gas streams. Other absorbents and configurations were also
examined.
3-1
-------
The absorbents were performance tested in 24-hour runs
3
at challenge levels from ambient to 118 y*cg/m . In addition, tests
were carried out in the presence of gaseous pollutants: hydrogen
sulfide, sulfur dioxide, chlorophenol, nitric oxide and xylene. None
of the pollutants modified the quantitative collection performance of
the absorbents.
As designed, the prototype canisters are made of PVC pipe.
Each is closed by a stainless screen held in place by a Lucite fitting
which is also used to stack the canisters. An aluminum plenum
houses the added assembly. The collection canisters may be emptied
directly into a Pyrex shipping container or each canister may be
enclosed in a sealed polyethylene shipping container and returned to a
central laboratory for analysis and refilling. Tests have shown stable
retention of mercury and its compounds by the absorbents for periods
up to six weeks.
Particulate samples are stored by carefully folding the glass
fiber particle filter and enclosing it in a polyethylene container for
mailing and storage.
An analytical procedure for each of the three separately col-
lected forms of mercury has been developed and tested. In principle,
it involves desorbing the collected sample into iodine monochloride
solution by application of heat to the sample; reduction of an aliquot
of the IC1 solution; collection of the resultant elemental mercury on
gold wire; heating the gold wire by an induction furnace to desorb the
concentrated mercury into a flameless atomic absorption spectrophoto-
3-2
-------
meter cell; and measurement of the desorbed mercury by standard
AAS light absorption techniques at 253. 7 nm. A number of variations
of the method are possible.
Data have been enclosed to support all claims. A proto-
type device was also developed for the sample transfer operation.
The latter consists of a crucible furnace and furnace insert to trans-
fer the mercury-containing gases to IC1 bubblers.
Detailed designs (drawings) of all developed parts are
included.
On 21 February, a demonstration of the operation of the
collection device was conducted before the Project Officer in the
Pomona laboratory.
3.2 RECOMMENDATIONS
Recommendations to improve the field utility, convenience
and operating costs include the following:
(1) It would be highly desirable to reduce the volume,
weight and potential cost of the PVC canisters and the absorbents
contained in each. Two approaches to resolution of this need might
be conceived: (a) the volume of adsorbents may be reduced by
careful determination and specification of the absorption capacity
requirement, air sample volume requirements, sampling time and
collection efficiency requirements; (b) two canister sizes might be
developed for industrial monitoring; a second for ambient determina-
tions, A series of interacting technical factors are involved in size
reduction including the efficiency and composition of the adsorbents
and the factors indicated above.
3-3
-------
Ancillary advantages to decrease in canister size include
reduction of the size of the plenum, improved ease in shipping,
increased convenience and precision in sample analysis, etc.
(2) Cost reductions may be achieved by development of a
less expensive adsorbent than the currently utilized 12% silver on
alumina. It is anticipated that reduction in silver content might
be achieved by definition of adsorption capacity, efficiency factors
and operating time so that a lesser safety margin than utilized in
the current adsorbent is specified. Also, new adsorbents may also
be employed.
(3) Operational expense may be considerably decreased by
development of methods for quantitatively regenerating the adsorbents.
(4) An area where considerable, simplification in the anal-
ytical method might be gained is related to recovery and extraction
of mercury - containing materials and transfer into iodine mono-
chloride solutions. Currently this transfer is achieved by heating
samples of absorbents in a furnace while simultaneously drawing air
through the furnace into IC1 bubblers. This procedure works well
enough, but direct extraction of each sample into liquid offers con-
siderable simplification. Initial tests with the particulate filter and
silver on alumina adsorbent indicate that both these two samples
appear tractable by liquid extraction. Use of sonicators or auto-
matic shakers appears useful in assisting in achievement of satis-
factory recovery results.
This procedure would reduce the amount of labor involved
in each analysis, eliminate problems associated with manipulations
3-4
-------
in a heated furnace, and potentially increase the precision of the
sample transfer process.
3.3 COMMERCIAL PRICE ESTIMATES
For purposes of reference only, the following estimates of
commercial sale prices for the components and services developed
under this project have been estimated. These price estimates
include standard commercial profit margins and are subject to
change for volume sales and, of course, in the event of technical
improvements and simplifications.
Estimated
Material Market Price
(a) Collection Assembly: $145.00
Designed for use with standard.Hi-Vol
Air Samplers. Includes stainless
steel plenum, canister holder, criti-
cal orifice and air flow controls but
without canisters or pressure gage;
complete with directions for use.
(b) Elemental Mercury Col- $ 49. 50
lection Canisters: Filled with 180 grams
of 10% silver on 1/8" alumina adsorbent
pellets.
(c) Combined Mercury Collection $ 22. 50
Canisters: Filled with 85 grams of 6-10
mesh activated charcoal.
(d) Particulate Collection Filters: $ 21. 50
Glass Fiber Filters, 8 x 10 inches, for
use with standard Hi-Vol samplers. In
packages of 100 sheets.
3-5
-------
Estimated
Material Market Price
(e) Shipping Containers: $ 7.50 per dozen
Wide mouth Nalgene bottles with
screw caps, 48 mm opening. For
shipment of canisters or folded
filters after presealing in plastic
envelopes (not included).
Analyses:
(a) Certified analysis, refilling $35.00
and return of Elemental Mercury
Canisters
(b) Certified analysis, $ 30. 00
refilling and return of Combined
Mercury Canisters.
(c) Certified analysis of $ 22. 50
Particulate Samples on 8 x 10 inch
glass fiber filters.
These estimates are presented for reference and should be utilized
as the bases for measurement of improvements.
3-6
-------
Section 4.0
EQUIPMENT DEVELOPMENT TABULATION
-------
Section 4.0
EQUIPMENT DEVELOPMENT TABULATION
The equipment developed under this contract consists of
elements of the test system, preliminary and Prototype collection
plenums, Prototype canisters and segments of the GEOMET mer-
cury recovery and analysis.
The following tabulation, Table 4-1, lists these items
along with their type, source and referenced drawings contained
within the text of this report.
4-1
-------
Table 4-1
EQUIPMENT TABULATION SHEET
Item
1. High-Volume Air Sampler
with Shelter (1 each).
Type
Unico 550 Turbine Jet;
with Wooden Shelter.
Source
Environmental Science
Div. , Bendix Corp.
Reference Section
2.3
2. Collection Plenum, Test.
(1 each)
GEOMET; with Probe for
Mercury Challenge
Monitoring.
GEOMET, Inc.
2.5, 2.7.2
3. Collection Plenum, Proto-
type configuration (1 each).
GEOMET; with Critical
Orifice for Monitoring
Canister Through-put Air
Velocity.
GEOMET, Inc.
Z.I.2
4. Dilution Air System
(1 each).
GEOMET; Includes Flow-
meters, Air Filter Canis-
ter, MAGNEHELIC Gage,
and Air Pump.
GEOMET, Inc. ; Dwyer
Instruments Inc. ;
Thomas Industries, Inc.
2.5
Prototype Absorbent
Canisters (6 each).
GEOMET; PVC plastic.
GEOMET, Inc.
2.7. 3
to
Prototype Canister
Closures (12 each)
GEOMET; LUCITE plas-
tic and Stainless Steel
Screen.
GEOMET, Inc.
2.7. 3
-------
OJ
Table 4-1 (Con't. )
EQUIPMENT TABULATION SHEET
Item
Type
Source
Reference Section
7. Crucible Furnace
(1 each).
Lindberg HEVI-DUTY,
Type 56312-A.
Lindberg Division,
(SOLA Industries)
2.7.4
8. Furnace Insert
(1 each)
GEOMET; with two (2)
interchangeable Nickel
Alloy Crucibles.
GEOMET; Van Waters
and Rogers Co.
2. 7.4
------- |