What is Water Hammer?

Water hammer is often first identified by the symptom of a vibrating sound within the pipework which makes a thudding sound several times a second within a closed-loop system. It can occur for several reasons and lead to reverse flow, pressure increase, fittings become loose and in severe cases cracked pump casings.

Some of the reasons why water hammer occurs are:

Valve closures

If a valve is closed too quickly such as a non-return valve or slam valve, the sudden stopping of the fluid can cause the momentum within the fluid to travel back and forth creating a vibration. Ideally, a valve should close slowly via a motorised action and the pump protected by a non-return valve

Pump shutdown

If a pump is switched off immediately this can cause a pressure surge within the pipeline. This can be suppressed by reducing the speed of the pump rather than shutting down the pump immediately. 

An air accumulator or pressure vessel can also be installed to maintain pressure in the pipeline as often the effect of turning off the pump can cause an immediate pressure drop at the pump inlet causing a surging effect of the fluid. A pressure vessel reduces the possibility of this happening.

System pressure

Another issue can be the system pressure which can be adjusted by a pressure reducing valve or by reducing system pressure slightly to see if this eliminates the water hammer

Do you have issues with water hammer and are looking at ways to resolve? A vfd may help reduce this, contact us to discuss your water hammer issue and for us to diagnose a solution.