Often a lever and weight or a lever and spring are mounted to achieve
optimum performance. Swing check valves with lever and weight are
appropriate for installations with an increased risk of water hammer at
standard velocities. Swing check valves with lever and external spring
are suitable for high pressure, insufficient back pressure and high flow
velocities.
An important thing to be aware of when installing a swing check valve
is, that it is not completely maintenance free since the disc needs to
be cleaned once in a while. Furthermore, a lever is often mounted to
enable visual check. Therefore, swing check valves are often installed
where personnel is present.
AVK swing check valves are designed with focus on easy access to
maintenance. By unscrewing a few bolts the bonnet assembly including
hinge and disc can be removed from the body, and maintenance can be
performed.
The light-weight disc of EPDM rubber with lip sealing and steel insert
requires a minimum of force to open and close the valve. The disc is
mounted in a nylon bushing, which allows it to move slightly both
horisontally and vertically to close completely tight also in case of
minor impurities in the seat. The seat is placed in a 20° angle
providing tightness even at low backpressure. The hinge is made of
acid-resistant stainless steel and is firmly tightened around the shaft
with bolts to eliminate play and thus to ensure durability. Where
limited space is available, the hinge can be placed in reverse position.
When mounted with lever and weight, the swing check valves in small
dimensions offer the possibility of priming by moving the lever
manually. The weight is adjustable on the lever to achieve a soft
closing against the seat as well as an optimum closing speed to prevent
water hammer. A guard covering the lever and weight is available as an
extra safety, as it eliminates the risk of injuries. The guard is
available with limit switches for remote monitoring.
