The Sampling Process
The objective of the sampling process is to collect a known quantity of pollutant from a known volume of effluent gas. This is accomplished by withdrawing a suitable amount of gaseous and particulate material using a sampling train.
The basic components of a typical sampling train consist of:
Schematic of Typical Sampling Train
A volume of sample gas extracted from the source is pulled through a pollutant collection device such as a filter or sorbent using a vacuum pump. The volume of the sample is measured using a calibrated dry gas meter. The sample rate is monitored using a calibrated orifice meter.
After sampling, typically an hour in duration or greater, the sample(s) is/are recovered from the sampling train and sent to an accredited analytical laboratory for analysis. The quantity of the pollutant collected during the test run is reported in terms of mass.
The pollutant concentration for a specific test run is the quantity of the pollutant recovered in the train divided by the sample volume recorded from the dry gas meter. Typically, the sample volume is expressed in terms of standard or reference conditions using the universal gas laws.
In Canada, reference conditions are 25°C and 101.3 kPa.
In the United States, standard conditions are 68°F and 29.92 Hg.
Source Testing (44 KB)