Have you ever heard a loud "bang" or "thud" in your pipes immediately after a faucet shuts off or a pump stops? That noise is known as water hammer, or hydraulic shock. While the sound is annoying, the physical reality is dangerous. Water hammer creates massive pressure spikes that can rupture pipes, damage pumps, and destroy valve internals.
In industrial settings—ranging from Power Generation to municipal water treatment—uncontrolled water hammer is a leading cause of catastrophic system failure.
Water hammer occurs when a fluid in motion is forced to stop or change direction suddenly. Water is incompressible; it has momentum. When a valve closes instantly, that momentum crashes into the valve plate, sending a shockwave traveling back through the pipe at the speed of sound. This shockwave expands and contracts the pipe, causing the characteristic banging noise and potentially exceeding the pressure rating of your PPR Pipes or metal fittings.
The most common culprits of water hammer are fast-acting valves (like solenoid valves) and pumps shutting down without flow control. However, the right choice of valves can mitigate these risks significantly.
Check valves allow flow in only one direction and close when flow reverses. However, how they close matters.
On the suction side of a pump, maintaining a prime is essential. If a pump stops and water rushes backward into the well or reservoir, it creates a vacuum and subsequent shock upon restart. Installing a high-quality UPVC Foot Valve ensures the column of water remains static when the pump is off, preventing the violent surge of water refilling an empty pipe.
For automated systems, the speed of the actuator is key. While pneumatic actuators are fast, closing a large butterfly valve in under a second on a long pipeline is a recipe for disaster. Using an Electric Actuated Butterfly Valve allows you to control the cycle time, closing the valve slowly over several seconds to dissipate energy gradually.
The material of your pipeline dictates how well it handles shock. Rigid metal pipes transfer the full force of the shockwave to fittings and supports.
Flexible plastic piping systems, such as PEX Pipes, have a lower modulus of elasticity. This means they can expand slightly to absorb the pressure surge, acting as a natural dampener. This inherent flexibility is one reason PEX and PERT Pipes are favored in residential plumbing where water hammer is a frequent annoyance.
Water hammer is not just a noise nuisance; it is a system killer. By combining the shock-absorbing properties of modern plastic piping with the correct selection of non-slam check valves and foot valves, you can extend the lifespan of your infrastructure.
For a deeper understanding of fluid dynamics and shockwaves, the Engineering Toolbox provides excellent calculation methods. If you are designing a system and need advice on valve placement to minimize hydraulic shock, explore our full range of Check Valves or contact our team for a consultation.
