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FUGITIVE EMISSION LEAK RATES FOR PROCESS EQUIPMENT
Fugitive emission studies have been done on a number of DuPont facilities and the
measurements were considerable lower than emission factors recommended by the EPA for
SOCMI chemical processes. These screening and bagging data have been used to establish
"typical" emission factors from DuPont facilities. The data separated into three categories of
emission levels for "as found" emissions form plants who were not involved in WAR
programs.
As a result of this effort, three sets of DuPont factors were developed: "superior", "excellent",
and "good." The superior factors are typical of processes that contain extremely hazardous
materials, i.e. phosgene (COC 12), chlorine (C 12), and. hydrogen fluoride (HF). A set of example
questions to help guide DuPont sites as to when to use the different categories was also
developed and is discussed in the next section. The three categories represent the range found
at DuPont facilities, but still are much lower than EPA SOCMI factors.
EMMISION FACTORS (Ib/hr/component)
COMPONENT
SERVICE
SUPERIOR
EXCELLENT
GOOD
EPA
SOCMIa
Pump Seals
Light Liquid
xxxxx
0.00115
0.0075
0.0439
Pump Seals
Heavy Liquid
xxxxx
0.00115
0.0075
0.0190
Valves
Gas
xxxxx
0.00039
0.00549
0.0132
Valves
Light Liquid
xxxxx
0.00036
0.00352
0.0889
Valves
Heavy Liquid
xxxxx
0.00036
0.00352
0.00051
Pressure Relief
Seals
Gas/Vapor
xxxxx
0.00012
0.00013
0.229
Open Ended
Lines
All
xxxxx
0.001
0.0215
0.00375
Flanges
All
xxxxx
0.00018
0.00031
0.00403
Sampling
Connections
All
xxxxx
0.00018
0.00031
0.0331
Compressor Seals
Gas/Vapor
N/A
N/A
N/A
0.503
Overall Emission
Factor
1/10,000
1/20
1/3
1/1
Note a: Protocol for Equipment Leak Emission Estimates, Table 2-1 (EPA-453/R-95-017)
Heavy liquid means a liquid with a true vapor pressure of less than 0.3 kPa (0.04 psia) at a
temperature of 294.3 °K (70 °F); or which has 0.1 Reid Vapor Pressure; or which when distilled
requires a temperature of 421.95 °K (300 °F); or greater to recover 10 percent of the liquid as
determined by ASTM method D86-82.
Light liquid means a liquid that is not a heavy liquid.
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Which factors should I use?
The factors suggested above represent DuPont "experience" and more accurately reflect
OVERALL fugitive emissions from DuPont facilities, i.e. the DuPont culture. The comparisons
were made with a limited database and the factors suggested here reflect a comparison of overall
or aggregate emission levels to those predicted by EPA SOCMI factors. It should be pointed
out that individual DuPont factors did vary from specific source service factors suggested by
EPA, i.e. light or heavy liquid service. For the "Superior" category, the individual factors are
extremely small numbers, and therefore, it is suggested to calculate the emission estimate with
EPA SOCMI factors, and then divide the total by the 10,000 factor. Since there is considerable
variability in ANY individual component leak rate due to type, age, size, service, etc., it is also
suggested to check overall predicted emissions from the "Excellent" and "Good" categories in
the same way, i.e. use EPA factors and then divide by 20 or 3, respectively.
In order to determine which factors to use, a series of questions were developed to index a
facility into one of the three categories. These are general guidance, and not definitive in the
sense of black or white. Additionally, use of the DuPont Factors may be challenged by State
Environmental Agencies since they do vary from EPA prescribed factors. However, past
validation efforts gave overall estimates within 10-20% of those based on DuPont factors.
Superior factors should only be used by facilities that use extremely hazardous materials, i.e.
phosgene, chlorine or HF. The maintenance culture of these operations is to detect and repair
leaks immediately due to the inherent toxicity of the chemicals. Most other processes/facilities
will be either excellent or good.
The "Excellent" factors listed above should be used only after HONESTLY answering the list
of questions attached, and at least 4 or 5 answers are "Yes." Otherwise use "Good".
QUESTIONS FOR DETERMINING UNIT -SPECIFIC FACTOR CATEGORY
1. Are techniques available and used to routinely locate specific leaks? Examples include SOz
bombs, ammonia solution, special detectors (such as those for HCN or phosgene), chemical
badges, and sniff testers. Yes, MSA hand held leak detectors are used
2. Do you perform leak checks in this process area at least once per day? Yes, the facility has
continuous monitoring of vinyl fluoride
Are specific procedures used on each start-up to minimized fugitive emissions? Examples
include hydrostatic tests, special leak tests, etc. Yes, start-up checklist and leak check
procedures
4. Do you have a documented checklist startup procedure that helps locate leaks? Yes,
repaired equipment is leak checked using hand held VF detectors following its startup
Do you have a formal procedure that requires leaks be repaired in a timely manner,
including use of overtime if necessary? Yes, the facility's leak check procedures require
that leaks be immediately repaired upon their discovery
DEQ-CFW 00065657