This standard applies to water meters and hot water meters used for transactions or certification in Japan that measure the volume of cold water of 30°C or less flowing in pipes that can withstand a maximum allowable working pressure of at least 1 MPa. This standard specifies hot water meters (hereinafter simply referred to as "meters" in the provisions common to both in this standard) that measure the volume of clean hot water below 90°C flowing through meters and pipes.