Determination of Stack Gas Velocity and Volumetric Flow Rate (Type S Pitot Tube)
EPA Method 2 applies to measurement of the average velocity of a gas stream with a pitot. The average gas velocity in a stack is determined from the gas density and from measurement of the average velocity head with a (Stausscheibe or reverse type) Type S pitot tube.
Velocity traverses are conducted by measuring flow at each sample point determined by the Method 1 calculations for stack gas velocity pressure ( ΔP) and stack temperature (Ts).
The operator takes velocity measurements before conducting a test or while performing a Method 5 test to determine the isokinetic sampling rate at each sample point. Volumetric flows are mathematically adjusted for temperature, pressure, and gas molecular weight.
For more information, please visit the EPA's Method 2 Webpage.
Equipment Needed for Method 2:
● flow measuring device;
● pitot tube, attached to M5 probe or independent;
● temperature measurement, attached to M5 probe or independent;
● sample line with negative/positive lines and TC passthrough; and
● Apex Instruments Sampling Console/Equipment:
○ XD-502
○ XC-53
○ DPT-B5