Swing check valves
AVK offers swing check valves in DN50-600 with lever and weight, lever and spring or with closed bushings. AVK swing check valves feature very easy access to maintenance and can be installed in horisontal or vertical position.
What is a swing check valve?
A swing check valve is mounted with a disc that swings on a hinge or shaft. The disc swings off the seat to allow forward flow, and when the flow is stopped, it automatically closes against the seat to block reverse flow. Shut-off characteristics depend on the weight of the disc and the return flow.
Swing check valves with lever and weight or lever and spring
To ensure optimal performance, swing check valves are often equipped with a lever and either a weight or a spring. The lever is often mounted to enable visual inspection, making swing check valves especially suitable for installation with regular personnel presence.
Swing check valves with lever and weight are appropriate for installations with an increased risk of water hammer at standard velocities. The solution enables visual inspection and the weight is adjustable on the lever to achieve a soft closing against the seat as well as optimum closing speed to prevent water hammer.
Swing check valves with lever and external spring offer a compact solution that does not depend on gravity of the lever's weight, making them suitable for installations where space is limited. It is the most responsive solution and is often chosen for vertical installations as well as for high-pressure conditions, insufficient back pressure or high flow velocities.
For enhanced safety, a guard covering the lever and weight is available as an optional extra. It eliminates the risk of injuries and protects against interference with the lever. The guard can be equipped with limit switches for remote monitoring.
Advantages of AVK swing check valves
AVK swing check valves are designed to allow for easy maintenance. The bonnet assembly, including the hinge and disc, can be removed from the body by loosening a few bolts.
Unique disc design
The light-weight disc of EPDM or NBR rubber with lip seal and steel insert requires minimal force to open the valve. It is mounted within a nylon bushing, enabling slight horisontal and vertical movement to ensure a tight seal, even if minor impurities are present. The seat is placed at a 20° angle providing tightness even at low backpressure. For increased durability, the hinge of acid-resistant stainless steel is firmly tightened around the shaft with bolts to eliminate play. Additionally, the hinge can be reversed for applications with limited space.
Preventing water hammer
When mounted with lever and weight, swing check valves in small dimensions offer the possibility of priming by manually moving the lever. The weight on the lever can be adjusted to achieve a soft close against the seat as well as optimal closing speed, effectively reducing water hammer.
AVK swing check valves are available in resilient seated design in DN50-300 and in metal seated design in DN350-600.
Main features of AVK swing check valves
- Bonnet/disc design gives easy access to maintenance
- Disc with steel insert is fully vulcanized with EPDM or NBR rubber (up to DN300) ensuring optimum sealing ability
- Lip seal on the disc ensures tightness
- Light-weight disc requires a minimum of force to open the valve
- The disc can move slightly horisontally and vertically for complete tightness
- Full bore ensures low head loss
- Ductile iron with 250 μm fusion bonded epoxy coating in compliance with DIN 3476 part 1 and EN 14901
- Bosses on each side of the valve seat allow tapping for connection of pressure gauge, by-pass, pressure sensors etc.
