A swing check valve is mounted with a disc that swings on a hinge or shaft. The disc swings off the seat for allowing flow and when the flow is stopped, the disc swings back into the seat for blocking the reverse flow. The weight of the disc and the return flow has an impact on the shut-off characteristics of the valve. Often a weight and lever or spring and lever are mounted to get optimum performances. Swing Check Valves with weight and lever are suitable for installations with an increased risk of water hammer at standard velocities. Swing Check Valves with external spring and lever are suitable for high pressure, high flow velocities, and insufficient back pressure. It is important to be aware that when installing a swing check valve, they are not completely maintenance-free as the disc requires to be cleaned once in a while. Furthermore, a lever is often mounted for enabling visual check. So, swing check valves are often installed in cases where a person is present.
The Swing Check Valves which we supply have been designed with a focus on east access to maintenance. By unscrewing a few numbers of bolts, the bonnet assembly including hinge and disc can be removed from the body and the maintenance operations can be completed. The light-weight disc of EPDM rubber with lip sealing and steer insert needs a minimum of force for opening and closing the valve. The disc has been mounted in a nylon bushing that makes it possible to move slightly vertically and horizontally for closing completely tight also in case of minor impurities in the seat. The seat is placed at an angle of 20 degrees which offered tightness even at low backpressures. The hinge is made up of acid-resistant stainless steel and is tightened firmly around the shaft with bolts for eliminating play and thus also ensures durability. Where limited space is available, the hinge can be placed in the reverse position. The swing check valves in small dimensions when are mounted with weight and lever offer the possibilities of priming by moving the lever manually. The weight can be adjusted on the lever for achieving a soft closing against the seat along with an optimum closing speed for preventing water hammer. A guard that covers the lever and weight is also present as an extra safety as it eliminates all the risks of injuries. The guard is available with limit switches for remote monitoring
.Features
- Tested for One Million Cycles per AWWA C508
- SCADA Compatible Limit Switch Assembly
- Non-Slam Closing Action - short 35° stroke
- Reinforced Disc - memory flex disc with 25 year warranty
- Mechanical Indicator
- Backflow Actuator - field installable
- Stainless Steel Construction available with viton disc
- Viton, Natural Rubber, Hypalon EPDM Disc Materials available
- Welded Nickel Seat available
- Bottom Mounted Oil Dashpot available
- Glass Lining available
- Rubber Lining available for abrasive and corrosive service
Specifications
1.Scope
1.1 This specification covers the design, manufacture, and testing of 2 in. (50 mm) through 48 in. (1200 mm) Swing-Flex® Check Valves suitable for cold working pressures up to 250 psig (1725 kPa), in water, wastewater, abrasive, and slurry service.
1.2 The check valve shall be of the full flow body type, with a domed access cover and only one moving part, the flexible disc.
2. Standards and Approvals
2.1 The valves shall be designed, manufactured, tested and certified to American Water Works Association Standard ANSI/AWWA C508.
2.2 The valves used in potable water service shall be certified to NSF/ANSI 61 Drinking Water System Components – Health Effects, and certified to be Lead-Free in accordance with NSF/ANSI 372.
2.3 Manufacturer shall have a quality management system that is certified to ISO 9001 by an accredited, certifying body.
3. Connections
3.1 The valves shall have flanges with drilling to ANSI B16.1, Class 125.
4. Design
4.1 The valve body shall be full flow equal to nominal pipe diameter at all points through the valve. The 4 in. (100mm) valve shall be capable of passing a 3 in. (75mm) solid. The seating surface shall be on a 45 degree angle to minimize disc travel. A threaded port with pipe plug shall be provided on the bottom of the valve to allow for field installation of a backflow actuator or oil cushion device without special tools or removing the valve from the line.
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