The Double Check Valve Assembly (DCVA) is essentially two single check valves assemblied within one body and furnished with four test cocks and two shut-off valves. Double checks are commonly used to protect against low to medium hazard installations such as food processing equipment or lawn sprinkler systems. They may be used under continuous pressure and protect against both backsiphonage and backpressure conditions.
A diagram of a double check valve is illustrated below:
Standardized Information for Double Check Valve Assemblies:
Installation type: Above and below ground, but no more than 24" deep or 5' above floor or grade respectively Safe to inject chemicals into system? No Okay to locate control valves downstream? Yes Okay to locate backpressure source downstream of assembly? Yes Installation height in relation to highest downstream piping: At point of connection Number of assemblies required One per system Use only in low to medium hazard applications? Yes Testing required after installation: annually Testing required after repairing or moving assembly? Yes Cost: Varies