What is Water Hammer? | DFT Inc.

Summary

This video explains the phenomenon of water hammer, a pressure surge caused when fluid in motion is suddenly stopped, often during pump shutdowns. It compares the effects of a traditional swing check valve versus a spring-assisted DFT silent check valve. The swing check valve can cause damage through slamming and pressure spikes, while the DFT valve closes ahead of reverse flow, minimizing water hammer and reducing damage. Independent studies confirm that DFT valves provide a more reliable, low-maintenance solution to prevent water hammer and protect piping systems.

Takeaways

• 😀 Water hammer is a shock wave that occurs when fluid in motion is suddenly forced to stop, often damaging piping systems and equipment.
• 😀 Swing check valves can cause water hammer due to their reliance on gravity and reverse flow to close, resulting in pressure spikes when they slam shut.
• 😀 The slamming action of swing check valves can lead to damage of sealing surfaces, hinge pins, and nearby equipment like pipe hangers and instrumentation.
• 😀 DFT spring-assisted silent check valves close proactively ahead of reverse flow, preventing water hammer and minimizing pressure spikes.
• 😀 By closing before the fluid's momentum changes direction, DFT silent check valves reduce the risk of damaging pressure surges in the system.
• 😀 Water hammer can create dangerous work environments, especially when it damages critical infrastructure such as pipes and instruments.
• 😀 DFT silent check valves are more reliable and require less maintenance than swing check valves due to their quick, non-slamming action.
• 😀 Independent studies have shown that DFT check valves favor fast closure, significantly reducing the risk of water hammer compared to traditional swing check valves.
• 😀 Choosing DFT check valves over swing check or double-door check valves can significantly reduce water hammer problems and improve system reliability.
• 😀 Visit dftvvalves.com to explore a full range of DFT's inline, nozzle-style, non-slam check valves designed to prevent water hammer and enhance system performance.

Q & A

What is water hammer and how does it occur?

Water hammer is a shock wave transmitted through a fluid in a piping system. It occurs when fluid in motion is suddenly forced to stop moving, often during pump shutdowns. The rapid deceleration of the fluid causes pressure spikes, resulting in potential damage to the piping system.

What causes water hammer in a swing check valve system?

In a swing check valve system, water hammer occurs when the valve closes abruptly due to reverse flow and gravity after a pump shuts down. The sudden motion of the valve causes pressure spikes that can damage pipe surfaces and components, including hinge pins.

How does the swing check valve contribute to water hammer?

The swing check valve allows gravity and reverse flow to close the valve, which causes it to slam shut. This sudden closure generates a pressure wave, known as water hammer, which can lead to damage to the pipe, hangers, and other system components.

How does a spring-assisted silent check valve differ from a swing check valve?

A spring-assisted silent check valve, like the DFT model, closes ahead of reverse flow during pump shutdown. The spring helps the valve close quickly and silently before fluid momentum changes direction, significantly reducing pressure spikes and preventing water hammer.

What role does the spring play in the DFT silent check valve?

The spring in the DFT silent check valve assists in closing the valve before the reverse flow occurs, allowing the valve to shut quickly and quietly. This prevents pressure spikes and reduces the occurrence of water hammer by ensuring the disc closes ahead of fluid momentum reversal.

What happens during pump startup in the two systems (swing check valve vs DFT silent check valve)?

During pump startup, both systems allow fluid flow. However, in the swing check valve, the fluid's motion and the slamming of the valve can cause damage. In the DFT silent check valve system, the valve operates silently and efficiently, with no sudden slamming, minimizing potential damage.

What are the advantages of using a DFT silent check valve over a swing check valve?

The DFT silent check valve offers significant advantages over the swing check valve, including reduced water hammer, minimal pressure spikes, and less wear and tear on components due to its quick and smooth closing mechanism.

How does the DFT silent check valve reduce the risk of water hammer?

The DFT silent check valve reduces water hammer by closing ahead of reverse flow before the fluid momentum can change direction, thereby preventing the buildup of pressure waves that typically cause water hammer.

What kinds of damage can water hammer cause in a piping system?

Water hammer can cause significant damage to piping systems, including damage to pipe hangers, instrumentation, and other components. It can also lead to unsafe working environments due to the high pressure and potential for system failure.

What types of valves can be replaced by the DFT silent check valve?

The DFT silent check valve can replace unreliable, high-maintenance valves such as swing check valves and double door check valves, offering a more efficient and long-lasting solution for preventing water hammer.