Isokinetic sampling procedure

The basic condition for a correct sampling is its isokinetic character. This means that during the analysed air sampling procedure, the gas flow rate through the opening of the sampling apparatus (inlet tubing) should... 

Procedure A sharp-edged nozzle is positioned in the duct, facing into the moving gas stream, and a gas sample is extracted isokinetically (see later) for a measured period of time. To allow for nonuniformity of particulate concentration in the duct, samples are taken at preselected positions in the duct cross-section. The particulate concentration is calculated from the weighed particulate mass and the gas sample volume. Figure 13.39 shows the measuring arrangement. 

Flue gas samples were taken over a 7 hour period for the 30 minutes residence time case and over a 2.5 hour period for the 15 minute case. These sampling times were chosen so that sufficient gas sample could be collected to demonstrate the required destruction efficiency. The flue gas sampling was conducted in accordance with a modified EPA Method 5 procedure and the ASME dioxin protocol (1). The samples were collected isokinetically at a single stack sampling point. At the conclu-... 

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