United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/S4-88/017 July 1988
f/EPA Project Summary
Sampling/Analytical Method
Evaluation for Ethylene Oxide
Emission and Control Unit
Efficiency Determinations
Joette Steger and William Gergen
The U.S. Environmental Protection
Agency (EPA) is currently
considering the development of
regulations to control ethytene oxide
(EO) emissions from commercial
sterilization facilities. Therefore, a
reliable sampling and analysis
method for measuring EO emissions
must be established. The method
must be capable of measuring total
EO emissions and must be
applicable to determining the
efficiency of EO control devices.
Measurement of EO emissions
from commercial sterilization
facilities is not a straightforward
process. The EO is emitted from the
chamber or control unit inter-
mittently, and the emissions vary in
intensity and EO content. This report
describes the results of a field
evaluation of a semi-continuous
direct sampling procedure applicable
to commercial sterilization facilities.
The facility chosen for the test
used a mixture of 12/88 (w/w)
EO/dichlorodifluoromethane (CFC-
12) as the sterilizing gas. Ethylene
oxide emissions to the atmosphere
were controlled using a com-
mercially available aqueous
absorption-hydrolysis system.
Samples of the exhausted gas
were continually removed from
sample ports located before and
after the EO control unit. Ethylene
oxide and CFC-12 concentrations
were analyzed at regular intervals
using an on-line gas chromatograph
equipped with dual gas sampling
valves, columns, and flame ionization
detectors. In addition, the oxygen
content of the gas exiting the control
device was measured at selected
intervals.
The volumetric flow rate from the
control device was determined from
differential pressure measurements
across two restricted orifice plates
Installed in parallel on the control
unit stack.
The method was evaluated for
repeatability, precision, and use-
fulness in determining the efficiency
of an aqueous absorption-hydro-
lysis control system.
This Project Summary was
developed by EPA's Environmenta/
Monitoring Systems Laboratory,
Research Triangle Park, NC, 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
A method for sampling and analyzing
ethylene oxide (EO) in the vent stream
from a sterilization chamber and a dilute
acid scrubber was field evaluated and the
method's usefulness for measuring
control unit efficiency was determined.
The U.S. Environmental Protection
Agency listed EO as a possible
hazardous air pollutant, creating a need
for standardized sampling and analytical
method to consistently determine control
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equipment efficiency. The evaluated
procedure used semi-continuous direct
sampling with on-line gas chro-
matographic analysis.
Using measured EO mass flow rates
into and out of the scrubber, scrubber
efficiencies were calculated. A
throughput efficiency was calculated
using the EO mass flow rates measured
at the inlet and outlet of the control unit
and a recovery that was equated to the
control unit efficiency was calculated
from the weight of EO charged into the
chamber and the measured EO emission
at the outlet of the control unit.
Facility Description
The field evaluation was conducted at
a commercial medical supply sterilization
facility that has three 28 cubic meter
chambers that use 12/88 sterilant gas.
The initial EO charge to the chamber was
calculated using the weight of the supply
cylinders before and after charging the
chamber.
The sterilizer exhaust is controlled by
a Chemrox DEOXX™ system, a dilute
acid scrubber that hydrolyzes the EO to
ethylene glycol. During the tests the
scrubber contained a mixture of dilute
phosphoric and sulfuric acid.
Each chamber is equipped with a total
recirculating pump with a gas/liquid
separator that emits the gas to the
DEOXX system and recirculates the
liquid to the pump inlet. All of the tests
were conducted using chambers
equipped with oil-sealed pumps.
The sterilization cycle is automatically
controlled by a programmable micro-
processor system that has the capability
to control and record the chamber
temperature, chamber pressure, and
elapsed time from the start of the cycle.
The tested sterilization cycles were
scheduled so that only one sterilizer
vented at a time.
Before the start of nine of the tests,
the chamber was evacuated to 2 pounds
per square inch absolute (psia) and then
pressurized to 3.1 psia with steam. Next,
the chamber was charged to 23.9 psia
with 12/88 gas. During each evacuation
and air in-bleed cycle, the chamber was
evacuated to 2 psia and pressurized with
air to 13.9 psia. For one test the chamber
was initially evacuated to 7 psia,
pressurized to 32.9 psia with 12/88 gas,
and cycled between 7 and 13.9 psia
during each evacuation and air in-bleed.
Sampling Locations
Samples were acquired before and
after the control unit. The scrubber inlet
sampling location, used to obtain a
continuous sample of sterilizer chamber
exhaust, was midway between the
sterilizer outlet and the scrubber inlet.
The exhaust was transferred from the
chamber outlet to the scrubber inlet via a
6-in. diameter poly vinyl chloride (PVC)
duct. Sample was acquired with 3/16-in.
Teflon probe. No direct flow mea-
surements were made at this location.
A continuous sample of scrubber
exhaust was obtained and volumetric
flow measurements were made at the
scrubber outlet. Exhaust exited the
scrubber vertically through a 6-in.
diameter PVC ductwork that exhausted
1.5 m above roof level. To measure
volumetric flow, the stack was modified
by installing 6-in. diameter PVC
ductwork and two butterfly valves to
divert the scrubber exhaust through one
of the parallel ducts, a 48-mm sampling
probe, two orifice plates in parallel, 1.9 m
[12.7 duct diameters] downstream of
their respective butterfly valves, and 40
cm [2.7 duct diameters] upstream of
their respective 90° bends, and wet and
dry bulb temperature probes.
Procedures
Sampling Procedures
Samples were taken simultaneously
from both sampling locations.
Ethylene Oxide Sampling
Sample was withdrawn into heated,
64-mm I.D., Teflon lines using Teflon-
lined diaphragm pumps. A 15-m line
was used on the inlet port and a 30-m
line was used on the outlet port.
Stainless steel, 64-mm tees were used
prior to the pumps to remove slipstreams
from the main sampling lines. The
slipstreams were routed through heated,
6-port, gas sampling valves that were
used to introduce the samples onto the
GC columns. Prior to the 6-port valves
were pumps with Teflon-lined
diaphragms and stainless steel, 64-mm
I.D., toggle operated shut-off valves.
Stainless steel fine metering valves and
rotameters were used after the 6-port
valves to control the flow rates of the
slipstreams. Before exhausting to the
atmosphere, the slipstreams and main
sample streams were routed through
dilute acid scrubbers to remove the EO.
Testing began when the DEOXX
scrubber started to exhaust in
preparation for the initial chamber
evacuation. Each test consisted of seven
evacuations, the initial chamber
evacuation, and pump down and six air
in-bleeds and subsequent evacuations.
Testing stopped at the start of thdl
seventh air in-bleed. The start time and
end time of the evacuations were
identified by flow or lack of flow across
the orifice plates.
The sampling lines were continually
flushed with sample throughout the test
day. Flow rates through the slipstreams
that flushed the gas sampling loops were
maintained at 100 ml/min. Samples were
isolated in the 6-port valves by closing
the shut-off valves simultaneously.
When the rotameters indicated no flow,
the sample loops were at atmospheric
pressure, and the samples were injected
into the GC.
After the first sample, samples were
acquired at three or four minute intervals
until the end of the first evacuation. For
the second through the seventh
evacuations the first sample was
acquired at either one, two or three
minutes after the start of the evacuation.
Again, samples were acquired at three to
four intervals.
Volumetric Flow Rate
Measurement
Volumetric flow rate measurements of
scrubber exhaust were performed at the
scrubber outlet location using two
standard, squared-edged orifice plates
with standard pipe taps mounted in
parallel ducts. The orifice diameters used
were 1.763-in. (4.48-cm) and 2.591-
in. (6.58-cm). Temperatures were
measured using a thermocouple and a
pyrometer.
Moisture Determination
The percent moisture of the stack gas
was determined by the wet bulb/dry bulb
method. Wet and dry bulb temperature
measurements were recorded at least
once during each exhaust episode.
Molecular Weight Determination
Nitrogen, oxygen, water, EO, and
CFC-12 were considered the main
components of the sterilizer exhaust gas.
The emissions of EO and CFC-12 were
continuously monitored by GC/FID.
Oxygen emissions were measured with
Fyrite oxygen indicator. The nitrogen
concentration was determined by
difference.
Percent levels of oxygen were usually
measured once during each evacuation.
For several of the runs oxygen was
determined at 1- or 2-min intervals to
determine the dead volume of the
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scrubber system. Sample was removed
from the stack upstream of the orifice
plates using an aspirator bulb to pull the
sample from the stack.
Analytical Procedures
The analytical method used for the
measurement of the EO and CFC-12
was gas chromatography with flame
ionization detection (GC/FID). The dual
FID Varian 3400 GC was equipped with a
Nutech heated valve box containing two
6-port valves. An 0.25 ml loop was used
on the inlet sample line and a loop of 2
ml was used on the outlet sample line.
The analytical columns were 10 ft (3 m) x
1/8 in. (3 mm) O.D. stainless steel
columns containing 5% Fluorcol on 60/80
Carbopack B. The FID electrometers
were connected to Shimadzu CR1-A
integrators.
The GC column oven was operated
isothermally at 100°C, the injector oven
at 175"C, and the detector oven at
200 °C. Nitrogen carrier gas flow rates
were 30 ml/min on the outlet channel and
60 ml/min on the inlet channel. Detector
support gas flow rates of 30 ml/min for
hydrogen and 300 ml/min for air were
used.
The same FID electrometer range was
used for the EO and CFC-12 on the inlet
channel but the range used varied from
10'9 to 10'11 depending on the inlet
sample concentration. The FID
electrometer range was programmed on
the outlet channel. A range of 10'1° to
10'12 was used for the EO and 10-8 to
10-1° was used for the CFC-12. The
electrometer range was programmed to
switch at 1.1 min during the first
evacuations and at 1.55 min during the
second through seventh evacuations for
optimum quantitation of both EO and
CFC-12.
Both channels of the chromatograph
were calibrated for EO and CFC-12 at
the beginning and end of the day. At
least one standard was also analyzed
between tests. Standards were
purchased from Scott Specialty Gases,
Scientific Gas Products, and MG
Industries and ranged in EO
concentration of less than 1 ppmv to
20% vol and in CFC-I2 concentration
from 1200 ppmv to 62.5% vol.
Calibration curves consisted of a
minimum of three standards.
Calculations
The data were reduced using LOTUS*
1-2-3 software. Rounding was
performed at the completion of the
calculations.
Ethylene oxide and CFC-12
calibration curves were prepared by
taking the logarithm of the peak area and
plotting that logarithm versus the
logarithm of the concentration. The EO
and CFC-12 concentrations were inter-
polated at 10-sec intervals for the first
evacuations. Usually, the concentrations
were assumed to increase linearly,
plateauing at a maximum determined by
an average of the data points after the
concentration versus time curve leveled
off. In some cases the concentration was
assumed to decrease linearly after
reaching a maximum and in other cases
the concentration was assumed to be
constant throughout the evacuation.
For the second evacuations the
concentrations were assumed to
decrease linearly where enough data
were present to validate that assumption.
In most cases an average concentration
was used. In all cases for the third
through seventh evacuations average
concentrations were used.
The molecular weight of the vent
stream was the sum of the molecular
weight of each component multiplied by
the mole fraction of that component in
the vent stream. For the first evacuations
the oxygen was assumed to decrease
exponentially from 20% to 0% vol. In
several cases for the second evacuations
the oxygen was assumed to increase
linearly; however, in most cases either
the average of all measurements was
used or a value of 19% vol was
assumed. For the third through seventh
evacuations the measured value was
used or, if no measurements were taken,
a value of 20% vol was assumed.
The EO mass flow rate into the control
unit was calculated based on the number
of moles of gas exiting the chamber
during each 2-min interval. Using the
chamber pressure and jacket
temperature, the moles of gas leaving
the chamber were calculated from the
ideal gas law, assuming that the chamber
gas did not significantly deviate from
ideal behavior at the chamber conditions
tested.
The weight of EO entering the control
unit during each time interval was given
by multiplying the moles of gas leaving
the chamber during each time interval by
the molecular weight of EO and the mole
fraction of EO in the gas. Summation of
the weights of EO entering the control
unit during each time interval
provided the total weight of EO entering
the control unit during the test period.
The EO emission out of the control
unit was calculated based on the pounds
of gas exiting the control unit during each
10-sec interval. The weight of EO
leaving the control unit during each time
interval was given by multiplying the time
interval by the mass flow rate of EO
leaving the scrubber during that time
interval. The total weight of EO leaving
the control unit during the test was
provided by adding the weights of EO
leaving the scrubber during each time
interval.
The total mass flow rate of gas was
calculated from the pressure drop across
standard orifices using equations taken
from the American Society of Mechanical
Engineers Research Committee on Fluid
Meters Report "Fluid Meters—Their
Theory and Application," 6th ed. 1971
Values for the specific heat ratio were
obtained form Perry's Chemical
Engineers' Handbook.
A Houston Instrument Digitizer was
used to convert the stripchart lines
representing continuous pressure
readings across the orifice plates into
numerical values.
The mass rate of EO flow out of the
control unit was then given by:
m = 60 X w X (PEO X MWEOVMWav (1)
where:
m = mass flow rate of EO, Ib/min,
w = total gas flow rate, Ib/s,
PEO = EO concentration, percent by
volume = ppmv/106,
MWav = molecular weight of the vent
gas, and
MWEO = molecular weight of EO
A throughput efficiency was calculated
using the emissions into and out of the
control unit. The throughput efficiency
(ET) is given by:
= lOOx(W,n-Wout)/Wu
(2)
A recovery efficiency was calculated
using the weight of the original EO
charge and the measured EO emissions
at the outlet of the control unit. The
weight of EO originally charged to the
chamber was obtained by multiplying the
weight of 12/88 gas by 0.12. No analysis
was performed on the sterilant gas to
verify the EO concentration. A correction
was made for the EO remaining in the
chamber (WR) which was determined
using the ideal gas law. The mole fraction
of EO left in the chamber was obtained
from samples taken after Evacuation 7
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either before or after the chamber had
been refilled. The recovery efficiency
(ER) is then given by:
ER = 100 x(Wc-WR-Wout)/(Wc-WR) (3)
where Wc is the weight of EO originally
charged to the chamber.
Results and Discussion
The sampling method was evaluated
using a gas cylinder containing known
concentrations of EO and CFC-12. The
gas cylinder was first analyzed on the
GC. Then the gas cylinder was treated
as a sample by installing a tee between
the cylinder and the sampling line. The
flow rate of the gas out of the cylinder
was adjusted so that there was always
excess flow past the tee during sampling.
Response of the cylinder sample through
the sample line was compared to the
response of the cylinder sample
analyzed directly.
The inlet sampling bias was measured
twice using a 2,508 ppmv EO and 6,022
ppmv CFC-12 standard. The total
sampling and analytical bias in the EO
measurement ranged from 0-7% with
an average of 3.5 percent. The sampling
bias in the EO measurement ranged from
0.2 to 11.9% with an average of 6
percent. In both cases the sampling was
biased positively for EO indicating that
the method would tend to overestimate
EO emissions. The total sampling and
analytical bias in the CFC-12
measurement ranged from 4.3 to 12.5%
with an average of 8.4 percent. The
sampling bias in the CFC-12
measurement ranged from 0 to 15.2%
with an average of 7.6 percent.
The outlet sampling bias was
measured three times using a 502.4
ppmv EO and 1,200 ppmv CFC-12
standard. The total sampling and
analytical bias in EO measurement
ranged from 1.9 to 12.9% with an
average of 7.4 percent. The sampling
bias in the EO measurement ranged from
-7.5 to 7.1% with an average of +1.3
percent. The total sampling and
analytical bias in the CFC-12
measurement ranged from - 9.5 to
4.8% with an average of -2.4 percent.
The sampling bias in the CFC-I2
measurement averaged 11 percent.
The analytical method was evaluated
using a gas cylinder containing known
concentrations of EO and CFC-12. The
gas cylinder was analyzed on the GC
using the same procedure as for the
standard cylinders. Using the response
of the cylinder sample and the prepared
calibration curve, a measured
concentration of the cylinder sample was
calculated. The measured concentration
was compared to the expected or known
concentration of the gas cylinder.
The inlet analysis bias was measured
twice using a 2508 ppmv EO and 6022
ppmv CFC-I2 standard. The analytical
bias in the EO measurement ranged from
-0.2 to -4.4% with an average of -2.3
percent. In both cases the analytical bias
was negative. The analytical bias in the
CFC-12 measurement ranged from
-2.4% to 4.3% with an average of 1
percent.
The outlet analysis bias was
measured three times using a 502.4
ppmv EO and 1200 ppmv CFC-12
standard. The analytical bias in the EO
measurement ranged form 0.3 to 10.1%
with an average of 6.2 percent. In all
cases the analytical bias in the EO
measurement was positive. The
analytical bias in the CFC-12 mea-
surement ranged from -5.6 to -18.5%
with an average of -12 percent. In all
cases the analytical bias in the CFC-12
measurement was negative, indicating
that the column may be overloaded by
the combination of the 2-ml sample size
and the high CFC-12 concentration.
The utility of the method in
determining emissions was evaluated by
comparing the measured EO emissions
for the six empty chamber tests on the
assumption that the control device
efficiency did not change with time.
The expected quantity of EO entering
the control unit during the six empty
chamber tests ranged form 41 to 44 Ib
and averaged 42 Ib, based on 12% of the
total weight of the 12/88 charge. The
measured quantity of EO entering the
control unit during these same six tests
ranged from 24 to 62 Ib and averaged 47
Ib. In the one test where the measured
weight of EO entering the scrubber was
24 Ib, the inlet sampling pump leaked
during the first 10 minutes of the
evacuation and the FID flame was
extinguished during portions of the third
and fourth evacuations. The two tests
where the measured weight of EO
entering the scrubber was above 60 Ib
were performed on a day when the EO
standard calibration curve for inlet
samples was lower than on other test
days.
The absolute difference between
measured emissions and expected
emissions was > 40% for three tests and
was < 10% for only one test. In five of
the six tests the measured emissions
were larger than the expected emissions.
The measured quantity of EO emitted!
to the atmosphere from the control unit
during the six empty chamber tests
ranged from 0.011 to 0.043 Ib and
averaged 0.022 Ib. The relative standard
deviation (rsd) in these six mea-
surements was twice the rsd for the inlet
measurements indicating that more
variation is associated with the scrubbing
process than with the sterilization
chamber.
Most of the error in EO emission
measurement probably resulted from
errors in the interpolation of the flow
rate/concentration profile. Ethylene oxide
emissions were measured with greater
precision at the scrubber inlet than at the
scrubber outlet as was expected because
of the higher concentrations at the inlet.
Part of this loss of precision in EO
emission measurement may be due to
difficulty in identifying the EO peak in the
chromatogram because of EO retention
times that shifted as the EO con-
centration decreased.
The utility of the method in
determining control unit efficiency was
evaluated by comparing the measured
throughput efficiencies obtained from the
six empty chamber tests on the
assumption that the control unit efficiency
did not change with time. All of the
empty chamber tests were performed on
the same chamber. The measured
efficiency using the throughput method
with the data from the six empty chamber
tests ranged from 99.82 to 99.98% and
averaged 94 percent. The median
efficiency was 99.96 percent. Efficiency
values were above 99.95% in five of the
six tests. The one test in which the
efficiency was below 99.9% was where
sampling and analytical problems were
encountered as described earlier.
Comparisons of the throughput and
recovery efficiencies were done by a
one-way analysis of variance (ANOVA)
with sampling-calculational procedures
as a fixed factor. The interaction term
between the calculational procedures was
tested to determine if there was a
significant effect on efficiency results
based on the calculational procedure
used. A probability (P) that the
calculational method used has no effect
was calculated. If P < 0.05, then the
effect is taken to be significant. A one-
way ANOVA resulted in a P of 0.86 for
the tests using chambers which did not
contain product and 0.32 for the tests
using chambers which did contain
product; therefore, the procedure used to
calculate the efficiency does not
significantly affect the efficiency
determined.
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The efficiency results from the tests
where product was present in the
chamber were compared with the
efficiency results from the tests where
product was not present in the chamber
using a fixed factor ANOVA. A probability
that the independent variable does not
effect the efficiency was calculated. If P
< 0.05, then the effect was taken to be
significant. The ANOVA calculation
resulted in a P of 0.59 for the interaction
between the calculational procedures; a
P of 0.37 for the interaction between the
chamber conditions; and a P of 0.79 for
the combined interaction of the
calculational procedure and chamber
condition.
Since none of the dependent variables
tested had a P s 0.05, there was
significant effect on the efficiency
measurement due to the presence of
product in the chamber. Furthermore,
there was no interaction between the
calculational method used and the
presence or absence of product in the
chamber. Thus, the efficiency results
were within random error of the overall
mean efficiency.
Several outlet EO emissions were
calculated using the chamber pressure
and temperature data used to calculate
inlet flow rates. No correction was made
for the change in the gas composition
that occurred while the gas was the
scrubber. The largest change in gas
composition occurs during the first
evacuation when the gas composition
changes from 30/70 % vol EO/CFC- 12
entering the scrubber to <1/>99 % vol
EO/CFC-12 exiting the scrubber. This
meant that during the first evacuation
approximately 30% of the moles of gas
entering the control unit did not exit the
control unit. Thus, the actual flow rate
coming out of the control unit was
probably less than the flow rate
calculated by this method. This method
should over-estimate EO emissions,
resulting in an under-estimation of the
control unit efficiency.
Statistical comparison of data based
on estimated flows with data base on
orifice plate measurements using a
one-way ANOVA with flow calculational
procedures as a fixed factor showed that
the EO emissions from the scrubber
calculated using orifice plate data were
not significantly different from the EO
emissions estimated using chamber
temperatures and pressures. The
probability that there was no difference in
the calculated EO emissions was 0.35; in
the calculated throughput efficiencies
0.59; and in the calculated recovery
efficiencies, 0.25. A probability of 0.05
indicated a significant difference. The
calculated efficiencies were not
significantly different due to the high
efficiency of the EO control unit.
Therefore, in tests performed on units
that are closed systems; therefore, flow
estimation may be a possible alternative
to orifice plate installation.
Conclusions and
Recommendations
Six conclusions were based on the
field test results. First, the
sampling/analytical method adequately
determined the EO mass flow rate into
the control unit. Most of the error
resulted from error in the interpolation of
the flow rate/concentration profile.
Second, the sampling/analytical
method adequately determined EO
emissions at the outlet of the dilute acid
scrubber, but identification of the EO
peak in the chromatogram was
complicated by EO retention times that
shifted as the EO concentration
decreased. The EO retention time shift
was magnified due to the large range of
EO concentrations. The bias in the
sampling/analytical method averaged
7.4% for EO and -2.4% for CFC-12.
Third, the sampling/analytical method
adequately determined the efficiency of
the dilute acid scrubber. Measured
efficiency calculated by the throughput
method for empty chamber tests ranged
from 99.82 to 99.98% and averaged
99.94 percent.
Fourth, the recovery method of
determining control unit efficiency was
comparable to the throughput method at
this site. Efficiencies calculated empty
chamber tests by the throughput method
ranged from 99.82 to 99.98% and
averaged 99.94 percent. Efficiencies
calculated for empty chamber tests by
the recovery method ranged from 99.90
to 99.97% and averaged 99.95 percent.
A one-way analysis of variance
(ANOVA) performed on the data for the
empty chamber tests showed that the
methods were not different. The sterilizer
chamber/control unit tested was a closed
system (i.e. leak-free) so this con-
clusion may not be valid at an older
facility where more EO may be lost from
the system as fugitive emissions.
Fifth, the presence of product in the
chamber did not affect the scrubber
efficiency measurement. The efficiencies
calculated for empty chamber tests by
the throughput method ranged from
99.82 to 99.98% and averaged 99.94
percent. The efficiencies calculated for
full chamber tests by the throughput
method ranged from 99.92 to 99.98%
and averaged 99.96 percent.
Sixth, EO emissions and control unit
efficiencies calculated using flow rates
based on orifice plate data did not differ
significantly for EO emissions and control
unit efficiencies calculated using
estimates based on chamber
temperatures and pressures. Ethylene
oxide emissions for empty chamber tests
based on orifice plate data ranged from
0.011 to 0.043 Ib and averaged 0.024 Ib.
Estimated EO emissions for the same
tests ranged from 0.006 to 0.036 Ib and
averaged 0.017 Ib. Throughput
efficiencies based on orifice plate data
ranged from 99.82 to 99.98% and av-
eraged 99.93 percent. Throughput
efficiencies based on estimated flows for
the same tests ranged from 99.85 to
99.99% and averaged 99.95 percent.
Again, the sterilizer chamber/control unit
tested was a closed system so this
conclusion may not be valid at an older
facility where more EO may be lost from
the system as fugitive emissions.
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Joette Steger and William Gergen are with Radian Corporation, Research
Triangle Park, NC 27709.
John H. Margeson is the EPA Project Officer (see below).
The complete report, entitled "Sampling/Analytical Method Evaluation for
Ethylene Oxide Emission and Control Unit Efficiency Determinations."
(Order No. PB 88-204 235/AS; Cost: $19.95, subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S4-88/017
080C3Z9 PS
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