This standard describes the double check valve backflow prevention assembly. The assembly shall be for operation on hot or cold water lines and capable of withstanding a working water pressure of at least 150 psi (1,034 kPa) without damage to working parts or impairment of function. This standard describes hot- and cold-water double check valve backflow prevention assemblies. Assemblies shall be designed to operate at a minimum temperature range of 33ºF to 140ºF (1ºC to 60ºC). Hot water assemblies shall be designed to operate, at a minimum, in water at a temperature range of 33ºF to 180ºF (1ºC to 82ºC). A complete assembly consists of two internally loaded, independently operating check valves, located between two tightly closing resilient-seated shutoff valves, with four properly placed resilient-seated test cocks (see Sec. 188.8.131.52). Major revisions made to the standard in this revision include the following: AWWA standard materials statement has been added (Sec. III.A.2 and Sec. 4.1); synthetic coating of ferrous bodies has been removed (Sec. 4.1.2); the material callouts have been updated (Sec. 4.1.3); the identification of nominal size of the assembly has been revised (184.108.40.206); the requirements for structural capability and operational capability have been revised (Sec. 220.127.116.11 and Sec. 18.104.22.168); the sections on area of waterways, clearance of moving parts, facing rings for poppet-type valves, facing rings for swing-type valves, and bushings have been removed (former Sec. 22.214.171.124 through Sec. 126.96.36.199); the requirements for shutoff valves have been updated (Sec. 188.8.131.52); requirements for operational cycle testing have been added (Sec. 184.108.40.206); and, requirements for replacement parts have been added (Sec. 4.3.4).