Rapid Closure Water Hammer Calculator
Compare Joukowsky pressure surge with the entered pipe-wave travel and valve-closure times.
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Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Apply the rapid velocity-change Joukowsky relation and compare closure time with2L/a.
Surge magnitude Δp=ρaΔv; wave round-trip time=2L/a
Worked example
Density1000kg/m³, wave speed1000m/s and velocity reduction1m/s give rapid-closure surge1MPa. A100m pipe has wave round-trip time0.2s.
Assumptions and input details
Density, entered system wave speed and pipe length are positive; velocity reduction and closure time are nonnegative. This reports a rapid-closure comparison magnitude, explicitly flagged when closure is slower than2L/a. It does not calculate a slow-closure surge, reflected-wave maximum, total absolute pressure, cavitation, pipe elasticity, air pockets, surge protection or an equipment pressure rating.
References: COMSOL: water-hammer verification and Joukowsky equation
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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