This standard covers 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 (1034 kPa) without damage to working parts or impairment of function. This standard covers hot- and cold-water double check valve backflow prevention assemblies. All assemblies shall be designed to, at a minimum, operate at a temperature range of 33F-110F (1C-43C). Hot-water assemblies shall be designed to operate in water at a minimum temperature range of 33F-180F (1C-82C). 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. The standard covers materials, design, workmanship, marking and delivery.