Watts 909 Reduced Pressure Zone Assemblies prevent the reverse flow of polluted water from entering into the potable water supply due to backsiphonage and or backpressure. It consists of FDA approved epoxy coated cast iron body construction with stainless steel trim, bronze ball valve shutoffs, and bronze test cocks. Series 909 features the patented "air-in/water-out" principle for protection during emergency combined backsiphonage and backpressure conditions It is ideal for health hazard cross-connections or for containment at the service line entrance. Check with local water authorities for installation requirements. Maximum Working Pressure: 175psi (12.06 bar).