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Swing check valves are of self-contained, free-swinging disc style, allowing a clear waterway. Valve disc swings freely open and is keyed to valve hinge pin without the use of pins. Valves conform to all standards set forth in AWWA C508, Latest Edition. Valve hinge pins are Stainless Steel and conform to the industry standards set forth for cushion valves. Manufacturer should have a minimum of ten years experience supplying air and oil cushion AWWA C508 valves.
• ANSI B16.1: Cast Iron Pipe Flanges and Flanged Fittings Class 125
• AWWA C508: Swing Check Valves for Waterworks Service, 2” through 24” NPS
Valves are rated for 150psi and 175psi water working pressure. Valves are available in ductile iron for high pressure applications. All testing is done in accordance with AWWA C508
Valves have integrally cast flat face flanges in accordance with ANSI B16.1 Class 125.
• All cast iron used conforms to ASTM A126 CLB
• Disc is of ductile iron conforming to ASTM A536 GR65-45-12
• Hinge Pins conform to ASTM A276 GR316
• Seat Rings are of Stainless Steel conforming to ASTM A276 GR316
Internal and external coatings are two-component epoxy conforming to AWWA C550.
All valves meet the standards of AWWA C508. All valves utilize a single disc mounted to a clevis hinge which prevents the disc from tipping. The valve disc swings open once the pump starts and allows for full flow. When closed the valve offers a tight shut-off. Valve body and cover are of Cast Iron; valve hinge is of Ductile Iron. Disc seating surface is Buna-N with seat holder of Stainless Steel. Valve seat rings are of Stainless Steel ASTM A276 GR316. Cover fasteners shall be Stainless Steel.
The valve body has a bolted cover design and flanges are integral to body casting – not wafer style. Valve body and disc are designed in such a way as to minimize turbulence. Spring and cushion systems are externally mounted on the side of the body and do not come into contact with main line media.
The three stage oil cushion system is totally enclosed, providing slow open and controlled closing to prevent surge and water hammer. Stage one shall be controlled by a timing valve, stage two by flow control valve and stage three by an internal cushion adjustment of the cylinder. Each stage is independently field adjustable in this totally enclosed system. The timing valve is plunger activated that makes contact with the cam on the hinge pin. Adjustment of the cam increases or reduces the closure speed of the swing check valve. The cushioning actions occur as the oil flows through the system.
All valves are built for horizontal installation. However, all valves operate equally well in vertical installations. Prior to valve installation, Pratt should be notified of vertical mounting position so lever arm and weight can be properly positioned on valve.