天然气.参数测量.容积参数:密度、压力、温度和压缩因子

[中文适用范围]： 本国际标准给出了主要用于体积计算和体积换算的天然气特性测量的要求和程序：参考和操作条件下的密度、压力、温度和压缩系数。 仅考虑那些适合天然气输送和分配条件下现场操作、在线或在线安装且不涉及气体成分测定的方法和仪器。 本国际标准给出了当前使用的商业化且天然气行业感兴趣的仪器的示例。 注：请注意国家授权机构批准的要求以及将这些设备用于商业或官方贸易目的的国家法律法规。 体积数据转换需要参考条件下的密度（有时称为正常密度、标准密度或基本密度），并且可用于其他物理属性。 使用观察到的线密度测量操作条件下的密度，用于质量流量测量和体积转换，并且可用于其他物理属性。 本国际标准涵盖基于振动元件的密度传感器，通常适用于 5 kg/m3 至 250 kg/m3 的测量范围。 压力测量涉及差压、表压和绝压变送器。 它考虑了模拟和智能变送器（即基于微处理器的仪器），如果没有另外说明，相应的段落指的是差压、绝压和表压变送器，没有区别。 天然气温度测量在正常传输和分配的条件范围内进行（253 K< 7' [外文原描述]： ISO 15970:2008 gives requirements and procedures for the measurement of the properties of natural gas that are used mainly for volume calculation and volume conversion: density at reference and at operating conditions, pressure, temperature and compression factor. Only those methods and instruments are considered that are suitable for field operation under the conditions of natural gas transmission and distribution, installed either in-line or on-line, and that do not involve the determination of the gas composition. ISO 15970:2008 gives examples for currently used instruments that are available commercially and of interest to the natural gas industry. The density at reference conditions (sometimes referred to as normal, standard or even base density) is required 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 the observed line density and can be used for other physical properties. ISO 15970:2008 covers density transducers based on vibrating elements, normally suitable for measuring ranges of 5 kg/m 3 to 250 kg/m 3 . Pressure measurement deals with differential, gauge and absolute pressure transmitters. It considers both analogue and smart transmitters (i.e. microprocessor based instruments) and, if not specified otherwise, the corresponding paragraphs refer to differential, absolute and gauge pressure transmitters without distinction. Temperature measurements in natural gas are performed within the range of conditions under which transmission and distribution are normally carried out (253 K < T < 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 the symbol Z ) appears, in particular, in equations governing volumetric metering. Moreover, the conversion of volume at metering conditions to volume at defined reference conditions can properly proceed with an accurate knowledge of Z at both relevant pressure and relevant temperature conditions.