Water Hammer Risk Estimator
Joukowsky surge analysis — pipeline period, closure time assessment, and surge mitigation guidance
System Parameters
Distance from the closing valve to the nearest tank, large header, or pump
Method: Joukowsky relation dP = rho x a x dV for instantaneous closure; linear-closure attenuation (dP x 2L/a divided by closure time) when closure exceeds the pipeline period 2L/a. Wave speeds are typical values — actual wave speed depends on pipe wall thickness, diameter, restraint, and entrained gas.
Limits: screening estimate for single-pipe liquid systems. Column separation, branched networks, pump trip transients, and condensate-induced steam hammer require transient simulation. Verify with a qualified engineer.
Closure is slower than the pipeline period (0.83 s), so reflections partially relieve the surge. The attenuated surge estimate is 10.0 bar — still more than half the operating pressure.
- Check the transient total against the pipe and valve design pressure including the occasional-load allowance (typically 33 percent over design per ASME B31.4).
- -Extending closure to 8.3 s or more would reduce the surge further
- -Verify check valves on connected pump discharges are non-slam type (dual-plate or axial)
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