Q:Impact Of Reverse Flow And Water Hammer On Check Valves.

Since TVCCL establishment, TVCCL has developed and grown after more than 20 years of hard work. It has won the recognition of more than 1,500 customers in 80 countries around the world. TVCCL is the first in the dual plate wafer type check valve industry in Taiwan. TVCCL has a competitive pricing, reliable quality product and excellent after-sales support, well-down packing.

Two of the most common problems with check valves are reverse flow and water hammer. In both situations, a fast-closing valve is desired. Reverse flow can be costly, especially if it occurs at the discharge of a pump and the pump spins backwards. The cost to repair or replace the pump, plus the plant downtime, far exceeds the cost of installing the right check valve in the first place. With water hammer, you need a faster-closing check valve to prevent pressure surges and the resulting shock waves that occur when the disc slams into the seat, sending noise, vibration, and hammering sounds that can rupture pipelines and damage equipment and pipe supports.
If the internals are missing or exhibiting wear, two factors may be occurring. First, if the check valve selected does not have enough flow passing through to keep it against its stop, a valve with a lower Cv is needed to prevent the moving/fluttering of the internals. Second, if the check valve is used at the discharge of a reciprocating air or gas compressor, a valve with a damped design or dashpot to handle high-frequency cycling is needed.

Sticking can occur when scale or dirt is trapped between the disc and body bore. Leakage can happen from damage to the seat or disc or simple trash in the line. An elastomer is needed to provide zero leakage.

Excerpt From
WaterWorld Magazine
Mike Shorts