How to Calculate Water Hammer
What is Water Hammer?
Water Hammer Pressure Calculator helps contractors and tradespeople accurately size, spec, and estimate materials and systems.
Formula
Surge Pressure = ρ × a × V / g where a=wave speed, V=velocity change
Step-by-Step Guide
- 1Calculate wave speed, multiply by velocity change and density
- 2Apply the formula using your project measurements
- 3Add required safety factors or waste allowances per code
Worked Examples
Input
V=5 fps change, a=4000 fps wave speed
Result
Surge = (62.4 × 4000 × 5) / (32.2 × 144) = 269 PSI
Common Mistakes to Avoid
- ✕Not applying code-required safety factors or derating
- ✕Forgetting to account for waste and cut losses in material estimates
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