Series 919 Reduced Pressure Zone Assembly Backflow Preventers are designed to prevent the reverse flow of contaminated water from entering into the potable water supply due to back siphonage and or backpressure. They have a bronze body construction, two poppet style check valves, and replaceable check seats, with an intermediate relief valve. Series 919 compact modular design facilitates easy maintenance and assembly access. It is ideal for protection at 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).