BS ISO 6578:2025

This document specifies the calculation procedure for converting the volume of liquefied petroleum gas (LPG) and liquefied natural gas (LNG) under the conditions at the time of measurement to the equivalent volume of liquid or vapour at the standard condition (i.e. 15 °C and 101,325 kPa absolute), or to the equivalent mass or energy (calorific content). This document applies to the quantities of refrigerated hydrocarbon liquids that are stored in or transferred to or from tanks and measured under static storage conditions. This document does not cover the calculation of pressurized gases.