Emissions calculation factors


Basic information on emissions factors

The EPA's Clearinghouse for Inventories & Emission Factors (CHIEF) provides a broad variety of information on emission factors from stationary point and non-point (fugitive, area) sources.

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Emission factors / AP 42 (Compilation of air pollutant emission factors)

This EPA document includes factors from a wide variety of industries and processes. Some factors are useful for estimating emissions associated with polyurethane manufacturing processes e.g. solvents or other volatile organic compounds (VOCs). These include chapters on evaporation loss sources and organic liquid storage tanks.

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WebFIRE (Factor Information Retrieval System)

This web site provides fast access via search functions to US EPA-recommended emission factors contained in the AP 42 document and other sources of emission factors for hazardous air pollutants, etc. The database includes numerous industries and processes, including those related to polyurethanes manufacturing. Search results include emission factor ratings, which are based on criteria that indicate the quality and basis used to determine the factors.

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Software tools

EPA maintains several resources for estimating emissions based on factors and/or associated engineering calculations. These tools include TANKS for estimating VOC and hazardous air pollutant (HAP) emissions from fixed- and floating-roof storage tanks, and WATER9 for estimating air emissions from wastewater collection, storage, treatment and disposal facilities.

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Emission factors for processes using isocyanates

Overall factors for MDI/TDI from various processes are available from the "isocyanate emissions toolbox" published by the Center for Polyurethanes Industry (CPI). High-level factors include emissions from MDI-based processes, flexible foam slabstock production using TDI, and MDI/TDI emissions from prepolymer and elastomer manufacturing processes. These data are tabulated under "Releases to atmosphere from polyurethane manufacturing sites."

Fugitive emission factors

For leaks from process equipment such as flanges, valves etc, the US EPA has developed a method for estimating isocyanates emissions (MDI/polymeric MDI) using emission factors for various equipment components. This method is described under "Fugitive Emissions" in CPI's document MDI/Polymeric MDI Emissions Reporting Guidelines for the Polyurethanes Industry.

Since there are limited published data on specific emissions factors for isocyanate mixtures, engineering calculations are especially useful for estimating emissions form specific unit operations and processes (see "Engineering Calculations").


Emission factors for polycarbonate processing

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