Volumetric Flow Rate – USEPA Method 2

USEPA Method 2 is used to determine the average velocity and the volumetric flow rate of a gas stream. The average gas velocity in a stack is determined from the gas density and from measurement of the average velocity head with a Type S (Stausscheibe or reverse type) pitot tube.
 
This method is not applicable at measurement sites that fail to meet certain criteria of USEPA Method 1.  Also, the method cannot be used for direct measurement in cyclonic or swirling gas streams. Method 1 shows how to determine cyclonic or swirling flow conditions.  When unacceptable conditions exist, alternative procedures, subject to the approval of the Administrator, must be employed to produce accurate flow rate determinations.  Examples of such alternative procedures are:
·       to install straightening vanes;
·       to calculate the total volumetric flow rate stoichiometrically;
·       to move to another measurement site at which the flow is acceptable.