| Water hammering occurs to some degree in all pressure systems.
Water hammering occurs with the sudden stopping and starting of the liquid delivery in the supply lines of a pump. These sudden changes in water velocity, deliver an intense impact load down the entire water line to the pump and accessories. It often creates a hammering noise and therefore referred to as water hammering. These impact loads can occur in a millisecond time frame and can deliver instantaneous damage to the system. Water hammering will cause damage to piping, system accessories and the pump.
Water hammering typically occurs with long feed lines or quick acting shut-off valves. Water hammering is a result of poorly designed inlet conditions resulting in liquid flow restriction, fluctuations in pressure and cavitation. Water hammering can generally be reduced with the installation of a pulsation dampener and flexible hose at the inlet and discharge ports of the pump. Using gradual bends rather than 90-degree elbows will also reduce the effect of the shock wave. A pressure reducing valve at the pump inlet can help protect the pump against high inlet pressure, however, these valves are not effective in protecting the pump from interrupted flow. Installing a C.A.T. [captive acceleration tube] may also help. It will store the liquid energy and minimize the cavitation risk, however, it does not correct for starvation.
When possible, it is recommended that a holding tank be installed at the pump inlet.
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