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Published on Apr 14, 2017
Water hammer is a shock wave, transmitted through fluid contained in a piping system. It occurs when fluid in motion is suddenly forced to stop moving, and frequently occurs at pump shut down.
We will be showing the difference between using a swing check valve, and a spring assisted D.F.T. Silent Check valve. Here you can see the fluid flow upon pump start up.
The motion and slamming of the swing check can cause damage to sealing surfaces, and fatigue… and wear to the hinge pins. When the pump shuts down, it is gravity and reverse flow that closes or slams the swing check valve closed, resulting in pressure wave build and water hammer.
Water hammer can also damage pipe hangars, instrumentation, and lead to dangerous work environments. Now you see an Excalibur model D.F.T. spring assisted silent check valve on pump start up.
When the pump shuts down, the spring assisted silent check valve closes as ahead of reverse flow, before fluid momentum changes direction, thereby significantly reducing water hammer.
Pressure spikes are minimal because the disc closes ahead of the reverse flow. Now you see a side by side comparison D.F.T.’s silent check valve and a swing check and after pump shut down.
University and independent laboratory studies have shown that the dynamic characteristic of the axial flow, spring assisted silent check valve… D.F.T. Check Valves… favors fast closing, ahead of reverse flow; therefore, reducing pressure spikes and water hammer.
Specify DFT Check Valves to replace your unreliable, high maintenance swing check or double-door check valves, and to significantly reduce water hammer problems.
Visit us online at D.F.T. dash valves dot com to view our complete selection of in-line, nozzle style, non-slam check valves.