ISO 19970:2017规定了量化液化天然气（LNG）运输船在货物运输操作期间为自身功能（尤其是发电）消耗的蒸发气体（BOG）的最低要求。本文件中的BOG是指从岸上储罐返回船舶储罐的低分子气体以及船舶货舱中产生的气体。 ISO 19970:2017规定了BOG计量和后续热值计算的要求，在确定货物运输过程中转移的能量时，可以考虑这些要求。 本文件还介绍了BOG测量系统中元件的性能要求和校准。只要满足本文件规定的性能要求，任何类型的流量计都可用于测量BOG。 ISO 19970:2017经过一些修改后，也可用于测量海上液化天然气运输船消耗的BOG。

ISO 19970:2017 specifies minimum requirements to quantify the boil-off gas (BOG) consumed on liquefied natural gas (LNG) carriers for their own functions, notably for power generation, during cargo transfer operations. BOG in this document refers to the low molecular gas returned from shore tanks to ships' tanks and the gas produced in ships' cargo tanks. ISO 19970:2017 provides requirements for the metering of BOG and the subsequent calorific value calculations which can be taken into account when the energy transferred during cargo transfer is determined. This document also introduces performance requirements and calibration of the elements included in the BOG measurement system. A flowmeter of any type may be used to measure BOG as long as it meets the performance requirements specified in this document. ISO 19970:2017, with some modification, can also be applied to the measurement of BOG consumed by LNG carriers at sea.