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Water Hammer

Water hammer, or hydraulic shock, occurs in pipelines due to sudden changes in fluid velocity, resulting in pressure waves that can cause noise, vibration, and damage. Key causes include sudden valve closure, rapid pump operation, trapped air, and improper pipe support. Mitigation measures involve using slow-closing valves, air chambers, and ensuring proper pipeline design and support to minimize risks.

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ramin safikhani
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19 views2 pages

Water Hammer

Water hammer, or hydraulic shock, occurs in pipelines due to sudden changes in fluid velocity, resulting in pressure waves that can cause noise, vibration, and damage. Key causes include sudden valve closure, rapid pump operation, trapped air, and improper pipe support. Mitigation measures involve using slow-closing valves, air chambers, and ensuring proper pipeline design and support to minimize risks.

Uploaded by

ramin safikhani
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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Water hammer, also known as hydraulic shock, occurs in pipelines when a sudden

change in the fluid velocity causes a pressure wave to propagate through the
system. This can result in noise, vibration, and damage to the pipeline or
equipment. The primary causes of water hammer are:
1. Sudden Valve Closure
 Rapidly shutting a valve can cause the fluid to stop abruptly, creating a
pressure wave that travels back through the pipeline.
2. Pump Start or Stop
 Starting or stopping a pump too quickly can lead to rapid changes in flow
velocity, generating water hammer effects.
3. Air Trapped in the Pipeline
 Air pockets in the pipeline can compress and expand, causing pressure
surges when the flow changes suddenly.
4. Rapid Demand Changes
 Sudden changes in demand, such as opening or closing downstream fixtures
(e.g., taps, sprinklers), can alter flow rates and cause water hammer.
5. Improperly Sized or Lack of Air Chambers
 Air chambers or surge arrestors are designed to absorb pressure surges. Their
absence or inadequate sizing can exacerbate water hammer effects.
6. Long Pipeline with High Flow Velocity
 In long pipelines, the inertia of the moving fluid can lead to significant
pressure waves if the flow is disrupted quickly.
7. Check Valve Slam
 A check valve closing rapidly due to backflow can cause a sharp pressure
spike.
8. Improper Pipe Support
 Insufficient or poorly installed supports allow pipes to move or flex,
intensifying water hammer effects.
9. Thermal Expansion
 Rapid temperature changes can cause expansion or contraction of the fluid,
leading to pressure waves.
Mitigation Measures
To reduce or prevent water hammer:
1. Install slow-closing valves or control valve speed.
2. Use air chambers or surge arrests near critical points.
3. Ensure proper pipeline supports minimize movement.
4. Employ variable-speed pumps to control flow changes.
5. Vent trapped air using air release valves.
6. Design the system with adequate pipe diameter and material to handle
pressure surges.
Understanding and addressing these causes during design, installation, and
operation can significantly reduce the risk of water hammering in pipelines.

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