DESCRIPTION:  This assembly consists of two internally loaded check valves, either spring-loaded or internally weighted as a unit between two tightly closing resilient-seated shutoff valves as an assembly, and fittings with properly located resilient-seated test cocks.


     FUNCTION:  During normal operation the check valves open, permitting flow.  If backflow conditions occur, the checks will close tightly, preventing any pollution of the supply.


     APPLICATION:  The double check valve is effective against backflow caused by backpressure and backsiphonage and is used to protect the water system from pollutants that would not constitute an actual hazard, but that might be objectionable to the water system.  The (DC) is used to isolate non-health hazard.