Hansen HCK5w/5, 5" (125mm) Gas Powered Suction Stop Valve.

These heavy-duty, durable, ductile iron or cast steel body, gas-powered suction stop valves are designed to control the flow of refrigerant in large industrial and commercial applications. They remain normally open via a spring and require no pressure drop to operate. A single pilot solenoid valve is required to control a higher pressure refrigerant gas which closes these valves during evaporator defrosting. If an electrical power failure occurs during the hot gas step of a defrost cycle, the auxiliary pressure pilot valve will keep main valve seat closed until pressure inside evaporator is reduced to the pressure setting on the pilot.