Finds gas flow rate, orifice diameter and differential pressure in accordance with this standard. The volume flow rate at line conditions and standard conditions are found along with the energy and mass flow rates using line density, standard density and calorific value (heating value).

References
American Gas Association Report No. 3 Part 4:1992, Natural Gas Fluid Measurement.
API MPMS Chapter 14.3:1992, General Equations and Uncertainty Guidelines – Concentric Square-edged Orifice Meters.