Equipment Emissions

Equipment emission measurements are made by a portable hydrocarbon analyzer at potential leak points. The analyzer is a flame ionization detector (FID) that measures total hydrocarbons over a range of 1 to 10,000 ppm on a logarithmic scale. Since these measurements are basic for regulatory compliance, procedures are formalized in the EPA's reference method 21.

Environmental engineers can determine emission rates from stand-alone equipment such as valves and pumps by using bagging tests in which the source is enclosed and leaks are captured in a known value of air or inert gas. Two different methods are commonly used: the vacuum method and the blow-through method. Figure 5.9.5 shows the blow-through method. Multiplying the concentration of the exhaust stream by the flow rate of air through the equipment calculates the emission rates. Samples are usually analyzed with a total-hydrocarbon analyzer. Toxics are detected by gas chromatography (GC).

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