ASTM International Standard Specification for Heat Meter Instrumentation ASTM E3137/E3137M-18

This specification applies to heat meters used to measure heat in heat exchange circuits in which energy is absorbed (cooling) or given up (heating) by a flowing liquid. For this specification, the necessary elements of a heat meter consist of a sensor to measure flow of the heat-conveying liquid, a pair of temperature sensors that measure the temperature differential across the heat exchange circuit, and a device that receives input from the flow and temperature sensors and calculates energy. This specification does not cover electrical safety or mechanical safety (including pressure safety). This specification defines heat meters as complete or combined instruments. A complete instrument refers to a heat meter that does not have separable subassemblies, while a combined meter is a heat meter that has separable subassemblies. It specifies the allowable flow rate maximum permissible error (MPE) by accuracy class and turndown; the combined allowable error percentages for the temperature sensor pair and the heat calculator for measured difference temperatures in -17°C [2°F] increments; maximum lead cross section and length requirements; types of instruments; metrological characteristics of flow sensors of heat meters and complete instruments; data exchange and communications protocols; heat meter testing methods; operating conditions during testing; type approval tests and measurements; surge transients for signal and dc lines; surge transients for ac power lines; carrier frequencies; field strength; initial verification tests; test temperature ranges; product marking and inscriptions; and installation and operation instructions.