Watts 957 - Reduced Pressure Principle Assemblies (RP) provide protection to the potable water system from contamination in accordance with national plumbing codes. RP’s are used in health-hazard applications for protection against both back siphonage and backpressure.
Watts 957RPDA - Reduced Pressure Detector Assemblies (RPDA) are installed on fire protection systems connected to the public water supply in a health-hazard application. The Watts 957RPDA is used to monitor unauthorized use of water from the fire protection system.
Most field problems occur because dirt or debris present in the system at the time of installation becomes trapped in the 1st check seating area resulting in a low or zero differential across the 1st check. The system should be flushed before the backflow valve is installed. If the system is not flushed until after the backflow valve is installed, remove both check modules from the valve and open the inlet shut-off to allow water to flow for a sufficient time to flush debris from the water line. If debris in the water system continues to cause fouling, a strainer should be installed upstream of the backflow assembly.
Watts Series 957/957RPDA may be installed in either a horizontal, “N” pattern, or “Z” pattern as long as the backflow assembly is installed in accordance with the direction of the flow arrow on the assembly and the local water authority approves the installation.
The assembly should be installed with adequate clearance around the valve to allow for inspection, testing, and servicing. Twelve inches should be the minimum clearance between the lower portion of the assembly and the floor or grade.