Provides information on the use of multiport averaging Pitot head-type devices used to measure liquids and gases. The Standard applies when the conduits are full and the flow: has a fully developed profile; remains subsonic throughout the measurement section; is steady or varies only slowly with time and; is considered single-phase. A differential pressure transmitter or other pressure measuring device known as a secondary element must be used with a multiport averaging Pitot primary element to produce a flow rate measurement. Although multiport averaging Pitot primary elements are sometimes used in non-circular conduits such applications are beyond the scope of this Standard.