标准编号：ISO 15970:2008
中文名称：天然气 性能的测量 容积性能：密度、压力、温度和压缩系数
英文名称：Natural gas — Measurement of properties — Volumetric properties: density, pressure, temperature and compression factor
发布日期：2008-06
标准范围
This international Standard gives requirements and procedures for the measurement of the properties ofnatural gas that are used mainly for volume calculation and volume conversion: density at reference and atoperating conditions, pressure, temperature and compression factor.Only those methods and instruments are considered that are suitable for field operation under the conditionsof natural gas transmission and distribution, installed either in-line or on-line, and that do not involve thedetermination of the gas composition.This International Standard gives examples for currently used instruments that are available commercially andof interest to the natural gas industry.NOTEAttention is drawn to requirements for approval of national authorization agencies and to national legalregulations for the use of these devices for commercial or official trade purposes.The density at reference conditions (sometimes referred to as normal, standard or even base density) isrequired for conversion of volume data and can be used for other physical properties.Density at operating conditions is measured for mass-flow measurement and volume conversion using theobserved line density and can be used for other physical properties. This International Standard coversdensity transducers based on vibrating elements, normally suitable for measuring ranges of 5 kg/m3 to250 kg/m3.Pressure measurement deals with differential, gauge and absolute pressure transmitters. It considers bothanalogue and smart transmitters (i.e. microprocessor based instruments) and, if not specified otherwise, thecorresponding paragraphs refer to differential, absolute and gauge pressure transmitters without distinction.Temperature measurements in natural gas are performed within the range of conditions under whichtransmission and distribution are normally carried out (253 K< 7'<338 K). In this field of application,resistance thermometer detectors (RTD) are generally used.The compression factor (also known as the compressibility factor or the real gas factor and given thesymbol Z) appears, in particular, in equations governing volumetric metering. Moreover, the conversion ofvolume at metering conditions to volume at defined reference conditions can properly proceed with anaccurate knowledge of Z at both relevant pressure and relevant temperature conditions.
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