This standard covers the use of displacement, turbine, Coriolis, and ultrasonic meters as master meters. 

The requirements in this standard are intended for single-phase liquid hydrocarbons. Meter proving requirements for other fluids should be appropriate for the overall custody transfer accuracy and should be agreeable to the parties involved. This document does not cover master meters to be used for the calibration of provers. For information concerning master meter calibration of provers, see API MPMS Chapter 4.9.3.