Determination of Volatile Organic Compound Leaks – USEPA Method 21

USEPA Method 21 is used for the determination of VOC leaks from process equipment.  These sources include, but are not limited to the following:

• valves, flanges and other connections
• pumps and compressors
• pressure relief devices
• process drains
• open-ended valves
• pump and compressor seal system degassing vents
• accumulator vessel vents
• agitator seals
• access door seals

A portable instrument is used to detect VOC leaks from individual sources.  The instrument detector type is not specified, but it must meet the specifications and performance criteria contained in the method.  A leak definition concentration based on a reference compound is specified in each applicable regulation.
 
This method is intended to locate and classify leaks only, and is not used as a direct measure of mass emission rate from individual sources.