This calculation corrects hydrocarbon volumes metered under pressure to the corresponding volumes at the equilibrium pressure for the metered temperature. It contains compressibility factors related to the meter temperature and density at 15°C of the metered material. The corresponding customary version is API MPMS Chpt. 11.2.2:1986 Amd.1994.

References
API Manual of Petroleum Measurement Standards Chapter 11 – Physical Properties Data - Section 2 Part 2M – Compressibility Factors for Hydrocarbons: 350-637 Kilograms per Cubic Meter (15°C) and -46°C to 60°C Metering Temperature, First Edition 1986