MDI Emissions Reporting Guidelines for the ... - Polyurethanes

Equipment Leaks
MDI Emissions Reporting Guidelines for the Polyurethanes Industry
In cases where monitoring data is not available, EPA has developed a method using emission factors
based upon the type of fittings and number of fittings used in the process. The methodology used for
MDI/PMDI is an adaptation of an EPA Correlation Method ("1995 Protocol for Equipment Leak Emission
Estimate" - EPA-453/R-95-017). The method presented here uses the actual formulas recommended
by the EPA except that saturated vapor concentrations are used instead of screening values. Since
the vapor concentration of MDI cannot exceed the saturation vapor pressure at a given temperature,
the predicted screening values are limiting and conservative values. The calculation methodology
involves the following steps:
1. Determine the saturated concentration of MDI.
2. Calculate emission factor for each equipment type.
3. Determine emissions for each equipment type.
4. Determine total losses from equipment leaks.
The MDI emissions from equipment leaks using the Modified Correlation Approach can be determined
using the following equations:
Where:
[(10.902 – 4634.09/(266.15 + t)]
SV = [1,315.8 x 10 ]
SV = Screening Value in ppmv and
t = Temperature in o C
The calculated Screening Value (SV) is then inserted into the Leak Rate/Screening Value Correlation
Formula for the appropriate equipment type (found in Table 5) and the leakage rate is determined.
Table 5
Leak Rate/Screening Value Correlations
Equipment Type Correlation Leak Rate (kg/hr) (a*(SV) b )
Gas Valve 1.87x10 -06 x (SV) 0.873
Light Liquid Valve 6.41x10-06 x (SV) 0.787
Light Liquid Pump Sealc 1.90x10-05 x (SV) 0.824
Connectors 3.05x10-06 x (SV) 0.885
c This equation can be used for liquid pumps, compressor seals, pressure relief valves, agitator seals and heavy
liquid pump seals.
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