United States
Environmental Protection
Agency
Risk Reduction Engineering
Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-88/063 Mar. 1989
&EPA Project Summary
Evaluation, Development and
Verification of Field Methods for
Rapid, On-Site Determination
of Appropriate Chemical
Protective Clothing
Todd R. Carroll and Arthur D. Schwope
Personnel involved in chemical
spill emergency response and
hazardous waste site activities often
have the need to make on-site
decisions regarding the effective-
ness and limitations of their available
chemical protective clothing. While
there are many existing test methods
for assessing the chemical
resistance of clothing materials,
none has been packaged, tested, and
accepted as a field kit. The purpose
of this effort was to develop a
prototype kit. Three gravimetric test
methods, which are typically used in
the laboratory, were evaluated for
their applicability and overall
usefulness in field kit form. The
methods evaluated were: an
immersion test, a degradation test,
and a permeation cup test. Baseline
data for comparison were obtained
using ASTM Method F739-85-
Standard Test Method for Resistance
of Protective Clothing Materials to
Permeation by Liquids and Gases.
Each method was evaluated using a
test matrix comprised of four neat
chemicals; three two-component
mixtures thereof; and two common
protective materials. The permeation
cup was selected as the preferred
method for field application. The
underlying principle of the
permeation cup is that chemical
contained in a cup that is covered by
the clothing material will permeate
and evaporate from the clothing
material. As this occurs, the weight
of the cup will decrease and from
measurements of the weight loss as
a function of time, the breakthrough
time and permeation rate of the
chemical through the material can be
calculated. Three prototype
permeation cup field kits were
fabricated and subjected to
preliminary user trials. The method is
also being considered for standard-
ization by ASTM. Preliminary results
from these trials were favorable;
additional laboratory and field testing
is recommended in order to establish
the validity and limitations of the
method.
This Project Summary was devel-
oped by ERA'S Risk Reduction
Engineering Laboratory, Cincinnati,
OH, to announce key findings of the
research project that is fully
documented in a separate report of
the same title (see Project Report
ordering information at back).
Introduction
EPA and EPA contractor personnel
involved in emergency spill response and
hazardous waste site activities normally
wear some form of chemical protective
clothing (CPC). Commercially available
CPC is fabricated from a wide variety of
polymeric materials. The effectiveness of
these materials as barriers to the
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chemicals or mixtures to which exposure
may occur is of primary interest to those
responsible for worker protection. The
chemicals and mixtures may be of
known or unknown composition.
Test data on the chemical resistance
of chemical protective materials are
available for only a small fraction of the
virtually infinite number of possible
chemical and material combinations. In
addition, essentially all of the data
generated to date are for neat chemicals.
The likelihood of finding data on the
exact chemical mixture/material
combination of interest is very small. The
need exists, therefore, for a field test
method that will enable field personnel to
rapidly determine the barrier
effectiveness of their available CPC to
the chemicals or mixtures at hand.
ASTM Method F739-85 and
analogous procedures have been
developed and are widely applied for
measuring the barrier properties of
protective materials. In general, these
tests are designed for and are performed
in the laboratory under controlled
conditions by skilled personnel. Typical
analytical techniques include: gas
chromatography, infrared spectrometry,
and atomic absorption. These methods
have allowed for significant advances in
clothing development and selection but
do not provide a useful means for field
personnel to assess CPC chemical
resistance in the field.
To meet the need for assessing the
chemical resistance of clothing materials
in the field, the applicability of three
candidate gravimetric test methods was
evaluated. They were an immersion test,
a degradation test, and a permeation cup
test. These tests are routinely used in the
laboratory for measuring the
performance of polymeric materials.
Baseline data for comparison were
obtained using ASTM Method F739-
85-Standard Test Method for Resistance
of Protective Clothing Materials to
Permeation by Liquids and Gases.
Procedure
The applicability of the three
gravimetric methods was judged
according to six criteria:
• The test should provide an estimate of
the breakthrough time (BT) and steady
state permeation rate (SSPR). It is not
necessary that the test actually
measure the BT or SSPR if good
correlations exist between these
parameters and the results of the test.
• The test method should be nonspecific
in that the permeation of any chemical
or mixture wpuld be interpreted as a
breach of the material being tested.
* The kit should be durable, portable and
self-contained, requiring no external
power. [
• The method should be simple to learn
and to perform. Minimal calibration
should also be required.
• The method development should
require a minimal amount of time and
cost. |
• The method should, at a minimum, be
applicable to a wide variety of liquid,
organic chemicals and clothing
materials. i
Each test method was evaluated using
seven chemicjal challenges (acetone,
hexane, methanol, toluene, and three
two-component mixtures of acetone
and hexane) and two clothing materials
(nitrile rubber and butyl-coated nylon).
Triplicate runs yvere made for each test
for each chemical/material combination
except for the jcase of ASTM F739-85
where the known precision of the method
and past experience with these
chemicals and materials made only
duplicate testirjg necessary.
Immersion Test
In the immersion test, a specimen of
the clothing material was weighed, then
completely immersed in the chemical or
chemical mixture, and at specified time
intervals removed, patted dry, and
reweighed. This test duration was 48
hours. Percentage weight changes were
calculated and visual observations
recorded. In many of the tests, the
weight change reached a maximum
value and then | fell off slightly. The peak
or highest perpentage weight increase
measured during the test was reported,
along with the time to reach the peak.
Degradation Test
A modification of a draft ASTM
degradation test procedure was used in
this study. The' normally outside surface
of the clothing' material was exposed to
the challenge chemicals for one hour.
The weight, thipkness, and elongation of
the material were measured before and
after the chemical exposure. The
percentage change in these parameters
was calculated! and reported along with
any visual observations.
Permeation Cup Test
The permeation cup test was
modelled after ASTM Method
E96-Moisture Permeability of Polymeric
Films. The CPC material is secured over
the mouth of a shallow cup containing the
chemical of interest and the cup inverted.
From measurements of the cup's weight
as a function of time, an estimate of the
BT and SSPR can be made.
ASTM Method F739-85
Baseline data for comparison of the
results from the immersion, degradation,
and permeation cup tests were obtained
using ASTM F739-85. In this test, the
clothing material separates two chambers
of a test cell. The chemical of interest is
charged into one chamber and the
concentration of the permeant in the
other chamber is monitored as a function
time. BT and SSPR are calculated from
the concentration data according to the
appropriate procedure specified in ASTM
F739-85.
Results and Discussion
Immersion Test
The immersion test satisfied five of the
six design criteria. The method is easily
learned and quickly performed. It is
nonspecific, applicable to a wide variety
of chemicals, and readily adaptable to a
field kit. Neither BT nor SSPR, however,
are easily determined from immersion
test data. Furthermore no validated
correlation exists between weight change
and BT or SSPR. Use of the test in the
field would require field personnel to
understand and depend upon rules of
thumb relative to the interpretation of
weight change data. For example, as
seen in Table 1, short BTs and high
SSPRs are typically associated with large
percentage changes in the weight of the
clothing material. There is also
remarkably good agreement between the
rankings of the results from the two tests,
i.e., the sequence of the chemicals in the
leftmost and rightmost columns.
Note in Table 1, however, that for the
same approximate weight changes, the
BT and SSPR are considerably different
for the two materials. The fact that there
is no general quantitative relationship
between weight change and permeation
test results is one major drawback of the
immersion test. Some materials exhibit
little or no weight change and yet have
short BT and high SSPR. Others such as
polyvinyl chloride can lose weight due to
the immersion. Effective interpretation of
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Table 1. Comparison of Immersion Test Results with ASTM F739
Nitrite
Immersion Test
Chemical
Acetone
Ace:Hex, 75:25 (v/v)
Toluene
Ace:Hex, 50:50 (v/v)
Ace:Hex , 25:75 (v/v)
Methanol
Hexane
% Weight1* Time*3 Resistance 87=
178 <1 Least 4.5
163 «r
748 <1
99 «1
52 «1
52 1
5.4
6
12
11
f 39.4
6 <1 Most nde
ASTM
SSPRd
8680
3280
1860
1330
650
86
nd
Test
Chemical
Acetone
Ace: Hex
Ace:Hex,
Toluene
Ace:Hex,
Methanol
Hexane
75:25 (v/v)
50:50 (v/v)
25:75 (v/v)
Butyl Nylon
Immersion
Chemical %
Toluene
Hexane
Ace:Hex, 25:75 (v/v)
Ace:Hex, 50:50 (v/v)
Ace:Hex , 75:25 (v/v)
Methanol
Acetone
Test
Weight a
103
72
59
22
13
11
8
Time13
<1
<1
<1
«1
«1
1
<1
Resistance
Least
i
Most
BTc
7
3.7
6
16
13.2
nd
nd
ASTM Test
SSPRd
529
463
328
95
83
nd
nd
Chemical
Toluene
Ace: Hex, 25:75 (v/v)
Ace:Hex, 50:50 (v/v)
Ace:Hex, 75:25 (v/v)
Hexane
Methanol
Acetone
a Percent weight change, average of three tests.
b Time (hours) to peak % wt. gain, average of three tests.
c Breakthrough time (minutes), average of two tests.
dSteady state permeation rate (tig/cm2 -mm), average of two tests. SSPR is the basis for ranking Resistance.
eNone detected in 6 + hours.
immersion test results requires a
knowledge of how specific materials
perform. Such knowledge is
unreasonable to expect of field
personnel. The test, moreover, is
inappropriate for an important category
of clothing materials. These materials
include multilayer structures and coated
fabrics in which only the outer layer is
designed to be chemically resistant. High
weight gains with such materials could
result from chemical absorption by the
inner layers which would not likely be
exposed to chemical in the actual use of
the garment.
Degradation Test
The degradation test is, for all
practical purposes, a single-sided
immersion test. Consequently the test is
applicable to multilayer or coated
clothing materials. Compared to the
immersion test, the method is somewhat
but not significantly more difficult and
time consuming to perform. The data in
Table 2 again show the general
relationship between high weight change
and low BT and high SSPR. Greater
changes in thickness also seem to
correlate with lower BT and high SSPR.
No correlation was found between the
change in elongation and BT or SSPR.
Similar to the immersion test, the key
drawback of the test is the difficulty in
data interpretation. Virtually all of the
issues mentioned for the immersion test
apply to the degradation test.
Permeation Cup Test
From the limited number of laboratory
tests performed to date, the cup method
appears to satisfy all six of the criteria for
the field kit. BT and SSPR are readily
estimated/calculated from the data and,
as is evident from Table 3, there was
good agreement between BT and SSPR
for the permeation cup test and ASTM
F739-85. The cup test is not capable of
distinguishing the identity of the
permeant. The values reported in the
table are for total permeant, independent
of composition.
For eight of the eleven chem-
ical/material combinations for which BT
was detected, the values for the
permeation cup were within ± 25% of
those for the ASTM test. SSPR from the
cup test were typically lower than but
within 50% of those from ASTM F739-
85. When the permeation cup results are
ranked from high to low SSPR, as in
Table 3, only one chemical/material
combination falls out of place when
compared to the ASTM F739-85 results.
These findings led to the conclusion that
the permeation cup was the most
promising of the candidate methods for
the field kit.
One recognized limitation of the
permeation cup procedure, as with any
permeation test in which a gas acts as
the collection medium, is that it may not
be applicable to chemicals having low
volatility. Evaporation of the chemical
from the surface of the clothing that is
exposed to the ambient air is required if
permeation is to be deduced from weight
loss data. If the volatility is low, then
evaporation could be the controlling step
and a true assessment of the barrier
properties of the CPC would not be
obtained. One solution to this problem is
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Table 2. Comparison of Degradation Test Results with ASTM F739 Results
Degradation
Chemical
Toluene
Acetone
Ace:Hex 50:50 (vlv)
Ace:Hex, 25:75 (vlv)
Ace:Hex, 75:25 (vlv)
Methanol
Hexane
test*
WT/TH/ELON
103/19/250
79/16/571
54/13/308
4/11/233
2/17/350
2/6/244
0.21-0.1125
Resist
i Nitrite
ance B7*
Least 4.5
^
5.4
6
12
11
, 39.4
Most ndd
ASTM Test
SSPRC
8680
3280
1860
1330
650
86
. nd . .
Chemical
Acetone
Acf.Hex, 75:25 (vlv)
Ace:Hex, 50:50 (vlv)
Toluene
Ace:Hex, 25:75 (vlv)
Methanol
Hexane
Degradation Test
Chemical
Hexane
Ace:Hex, 25:75 (vlv)
Toluene
Ace:Hex, 50:50 (vlv)
Ace:Hex, 75:25 (vlv)
Acetone ,
Methanol
WT/TH/ELON
59/60/nd
40/46/nd
31/31/nd
14/15/nd
10/W/nd
6/5/nd
4/2/nd
Resist
Butyl Nylon
wee
Least
^
Mo'st
B7*
7
3.7
6
16
13.2
nd
nd
ASTM Test
SSPRC
529,
463
328
95
83
nd
nd
Chemical
Toluene
Ace:Hex, 25:75 (v/v)
Ace:Hex, 50:50 (v/v)
Ace:Hex, 75:25 (vlv)
Hexane
Methanol
Acetone
^Percentage changes in weight (WT), thickness (TH), elongation (ELON), averages of three tests.
b Breakthrough time (minutes), average of two tests. '
c Steady state permeation rate (itg/cm2 -min), average of two tests. SSPR is the basis for ranking Resistance.
detected.
to physically remove by wiping or other
procedure the chemical from the surface.
Neither the limits of applicable vapor
pressure nor alternative approaches for
removing surface chemical were
explored in this study. A plan for doing
so was suggested.
Field Kit Development
The favorable results from the
laboratory investigation of the permeation
cup test method led to the development
of a permeation cup field kit. Three
prototype, self-contained field kits were
fabricated and included the following:
three permeation cups and stands; a 100
gram capacity, battery-powered
balance; instruction manual; and assorted
paraphernalia.
The accuracy and precision of the cup
test are principally determined by the
accuracy and precision of the balance
and the evaporation rate of the permeant.
Since the results of the cup test are
obtained from weight differences, a
balance with good precision is preferred
over one having high accuracy. At the
time of this study, the most precise,
battery-powered balance with the
necessary capacity (100 grams) had a
precision of ± 0.01 gram. More precise,
battery-powered balances are expected
in the future. Also if the criterion that the
kit be totally self-contained were
dropped, then balances powered by
alternating current could be used and
precision to four or five decimal places
would be attainable.
User Trials j
Three groups of EPA or EPA
contractor field personnel have tested the
kit, with mixed results. In one case the
contractor discontinued the use of one
type of CPC ^material after measuring a
more rapid breach of the barrier than was
acceptable.
L
Conclusions and
Recommendations
Gravimetric methods are expedient
and useful means for providing field
personnel with information on the likely
chemical resistance of protective clothing
materials. Of the three methods
evaluated, that based on the permeation
cup method was chosen for the field kit.
wa
The permeation cup test is simple and
easy to perform, produces BT and SSPR,
and is readily conformed into a durable,
self-contained kit for field application.
In addition to its utility as a user kit,
the permeation cup test appears to be an
attractive alternative to the more costly
and time-consuming ASTM Method
F739-85. With the availability of
analytical balances in the laboratory, this
method can produce results remarkably
similar to results generated using F739-
85. The test can also be used to identify
the most promising materials for
subsequent testing with ASTM F739-85
and to help establish the intervals for
sampling in that test. It is, however,
essential that the limitations of the
method imposed by the volatility of the
permeant be considered.
The initial laboratory and field results
of the permeation cup field kit are
promising but have been obtained under
a narrow set of conditions. The continued
investigation of the permeation cup test
method in both the laboratory and in the
field is recommended. The range of
limitations and applicability of the method
must still be investigated before the
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Table 3. Comparison of Permeation Cup Test Results with ASTM F739
Cup Test
Chemical
Acetone
Ace:Hex,
Ace:Hex,
Toluene
Ace:Hex ,
Methanol
Hexane
75:25 (v/v)
50:50 (v/v)
25:75 (v/v)
era
2.7
4.7
6.7
13
9.3
50
ndc
Nitrile
SSPRb Resistance BT
2590 Least 4.5
1760
1170
727
560
45
5.4
6
12
11
39.4
nd Most nd
ASTM Test
SSPR
8680
3280
1860
1330
650
86
nd
Chemical
Acetone
Ace: Hex,
Ace:Hex,
Toluene
Ace:Hex,
Methanol
Hexane
75:25 (v/v)
50:50 (v/v)
25:75 (v/v)
Butyl Nylon
Chemical
Toluene
Ace:Hex, 25:75 (v/v)
Ace:Hex, 50:50 (v/v)
Ace:Hex, 75:25 (v/v)
Hexane
Methanol
Acetone
Cup Test
BT
8.7
7.3
6
13.7
30
nd
nd
SSPR Resistance SSPR
282 Least 530
323
200
76
51
nd
nd Me.
460
330
83
95
nd
st nd
ASTM Test
BT
7
3.7
6
13.2
16
nd
nd
Chemical
Toluene
Ace: Hex, 25:75 (v/v)
Ace:Hex, 50:50 (v/v)
Hexane
Ace:Hex, 75:25 (v/v)
Methanol
Acetone
"Breakthrough time (minutes), average of three tests for cup test and two tests for ASTM test.
& Sfeady stefe permeation rate (fig/cm2 -mm), average of three tests for cup test and two tests for ASTM test. SSPR from the ASTM test is the
basis for ranking Resistance.
0 None detected in 1 hour for cup test or 6 hours for ASTM test.
method can be completely validated and
recommended for field implementation.
In addition to the volatility of the
permeant, the effects of environmental
conditions such as temperature and air
velocity across the cup face must be
quantified.
This report was prepared for the
Releases Control Branch of the U.S.
Environmental Protection Agency's Risk
Reduction Engineering Laboratory in
fulfillment of contract number 68-03-
3293.
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Todd R. Carroll and Arthur D. Schwope are with i Arthur D. Little, Inc.,
Cambridge, MA 02140. I
Michael D. Royer is the EPA Project Officer (see below).
The complete report, entitled "Evaluation, Development \and Verification of Field
Methods for Rapid, On-Site Determination of Appropriate Chemical
Protective Clothing," (Order No. PB 89-118 6731 AS; Cost: $28.95, subject to
change) will be available only from: i
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at: \
Releases Control Branch
Risk Reduction Engineering Laboratory-Cincinnati
U.S. Environmental Protection Agency
Edison, NJ 08837-3679 [
United States
Environmental Protection
Agency
Center for Environmental! Research
Information i
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S2-88/063
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