Fluid MechanicsFull Glossary

Water Hammer

A pressure surge caused by the sudden change in fluid velocity in a pipeline - most commonly when a valve closes rapidly and the kinetic energy of the moving fluid converts to a pressure wave. Can cause pipe, valve, and fitting failure. Prevented by slow-closing valves, water hammer arrestors, or air vessels.

Frequently Asked Questions

What is Water Hammer in the context of industrial valves?

A pressure surge caused by the sudden change in fluid velocity in a pipeline - most commonly when a valve closes rapidly and the kinetic energy of the moving fluid converts to a pressure wave. Can cause pipe, valve, and fitting failure. Prevented by slow-closing valves, water hammer arrestors, or air vessels.

How does Water Hammer affect valve selection and sizing?

A pressure surge caused by the sudden change in fluid velocity in a pipeline - most commonly when a valve closes rapidly and the kinetic energy of the moving fluid converts to a pressure wave. Valve sizing must account for this phenomenon to prevent premature failure, excess noise, and vibration. For control valves, ISA-75.01 and IEC 60534-2-1 cover sizing for incompressible and compressible flow. Vajra Industrial Solutions can assist with valve sizing calculations - contact sales@vajravyuh.com with your process data sheet.

What valve types minimise Water Hammer problems?

The choice of valve type and trim significantly affects susceptibility to flow-related problems. Anti-cavitation trims, low-noise cages, multi-stage pressure reduction, and proper Cv sizing reduce velocity-related damage. For critical applications, control valve sizing is performed using the ISA/IEC methodology with FL (liquid pressure recovery factor) and Fd (valve style modifier) for the specific valve geometry.

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