The Reduced Pressure Principle Backflow Preventer shall be certified to NSF/ANSI/CAN 61, ASSE® Listed 1013, and supplied with full port gate valves. The main body and access covers shall be epoxy coated ductile iron (ASTM A 536 Grade 4), the seat ring and check valve shall be NORYL™, the stem shall be stainless steel (ASTM A 276) and the seat disc elastomers shall be EPDM. Center stem guided design shall incorporate two torsion springs to bias the check in the closed position. The first and second checks shall be accessible for maintenance without removing the relief valve or the entire device from the line. If installed indoors, the installation shall be supplied with an air gap adapter. The Reduced Pressure Principle Backflow Preventer shall be a ZURN WILKINS Model 475 or 475V.
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Keywords: Reduced Pressure Backflow Preventer, backflow regulator, hazard protection, retrofits, Compound Check, Reduced Pressure Principle Assembly, Reduced Pressure Detector Assembly, Reduced Pressure Principle assemblies, water hammer, water thermal expansion, ample drainage, Backflow Preventer, shut-off valves, relief valve, water hammer shock arrestors, water pressure reducing valves, check valves, gauge scale