This standard specifies the technical characteristics, measurement characteristics and pressure loss of hot water meters. This standard is applicable to the common flow range of 0.6m^(3)/h~400m^(3)/h, the maximum allowable working pressure (MAP) is 1MPa~4MPa, the lower limit of the maximum allowable temperature (MAT) is greater than 30℃, and the upper limit is It is a hot water meter of 90℃, 130℃ or 180℃. This standard applies only to volumetric and velocity water meters. This standard must comply with relevant national regulations.