This document is to be used in conjunction with AGA Report No. 3, Orifice Metering of Natural Gas and Other Related Hydrocarbon Fluids (also published as API MPMS Chapter 14.3, and ANSI 2530). It is intended to be used as an operating guideline, not as a standard.

A number of technical issues have been addressed with respect to using differential pressures higher than 100 inches w.c. with simply-supported, flange-tapped orifice meters. These topics include the effects of orifice plate deflection, the discharge coefficient equation, expansion factor, change in tap hole location, and seal ring leakage.