Reduced Pressure Zone (RPZ / ASSE 1013) assemblies provide the highest level of mechanical backflow protection against toxic, high-hazard contaminants. Engineered with two independent check valves separated by a hydraulically operated differential pressure relief valve, an RPZ automatically dumps contaminated water to the atmosphere if backsiphonage or backpressure occurs. We install, certify, and overhaul commercial RPZ assemblies across all Western North Carolina mountain districts.
RPZ assemblies are legally mandated at commercial kitchens, car washes, medical and dental facilities, chemical injection stations, commercial boilers, and large irrigation systems where chemical backflow would pose an acute health hazard. We verify proper installation height, adequate drain capacity, and minimum clearances.
The differential pressure relief valve must crack open whenever the pressure zone between the two check valves drops to within 2.0 PSI of the supply pressure. Our precision gauges measure exact opening thresholds and check for disc fouling caused by Appalachian abrasive quartz grit or mica sediment.
RPZ assemblies discharge water during relief cycles and must never be installed inside underground pits where discharge ports could become submerged. For outdoor installations subject to WNC winter freezes, we install ASSE 1060 Class 1 freeze-proof heated aluminum enclosures with internal thermostatically controlled heat trace.
When check valve discs score or relief valve diaphragms harden, we install factory-matched repair kits including new rubber discs, O-rings, stainless steel springs, and bronze seat rings for Watts 009/909, Febco 860, and Wilkins 975XL2 assemblies.
Our technicians arrive with calibrated 5-valve test equipment and file your official compliance report directly with your municipal water purveyor.
Schedule Same-Day / Priority InspectionRPZ relief valves discharge water for two reasons: normal pressure fluctuations that cause the differential to drop below 2.0 PSI, or internal fouling where grit, mica, or mineral scale lodges in the first check valve, allowing high downstream pressure to push the relief valve open. An immediate service inspection is needed to diagnose and clean the assembly.
RPZ valves can be installed indoors provided they are equipped with an approved air gap drain funnel and routed to an adequate gravity drain capable of handling full discharge flow. They cannot be installed where flooding could submerge the relief valve port.
An RPZ includes a hydraulic relief valve and is approved for high-hazard toxic cross-connections. A Double Check (DCVA) lacks a relief valve and is only approved for low-hazard non-toxic applications such as fire sprinkler systems without chemicals or standard commercial containment.