This Surge / Water Hammer Analysis spreadsheet from 3D-LABS follows AWWA M11 and gives instant, checkable results for practising engineers — no manual derivation required.
This spreadsheet analyses water hammer (surge) in water mains and rising mains using the Method of Characteristics (MOC) and the Joukowsky equation per AWWA M11 (Steel Pipe Design Manual), CIRIA C680 (Pressure Transients in Water Engineering), and EN 805:2000. Surge analysis is mandatory for any pumping main or water transmission main before final design sign-off.
What standard does this calculation follow?
AWWA M11 (Steel Pipe — A Guide for Design and Installation, 5th Ed.), CIRIA C680:2004 (Pressure Transients in Water Engineering), EN 805:2000 (Water supply — Requirements for systems outside buildings), and ASME B31.4 for steel mains.
What formula is used?
Joukowsky surge pressure: ΔP = ρ × a × ΔV, where a = wave speed = √(K/ρ) / √(1 + KD/eE) (m/s), ρ = fluid density (kg/m³), ΔV = velocity change (m/s), K = bulk modulus of water (2.1 GPa), D = pipe diameter, e = wall thickness, E = pipe material Young’s modulus. Critical closing time: Tc = 2L/a seconds.
Frequently Asked Questions
What is the Joukowsky formula for water hammer pressure?
Joukowsky (1898) surge pressure: ΔH = aΔV/g (m head) or ΔP = ρaΔV (Pa), where a = pressure wave speed (800–1,200 m/s for steel pipes), ΔV = sudden velocity change (m/s), g = 9.81 m/s². For a 0.5 m/s pump trip in a DN600 steel main (a = 1,100 m/s): ΔH = 1,100 × 0.5 / 9.81 = 56 m head surge.
What is the critical closing time for a valve to avoid surge?
Critical (Allievi) closing time: Tc = 2L/a, where L = pipe length from pump to valve (m), a = wave speed (m/s). If Tc > 2L/a, the valve is “slow” and reflected wave arrives before closure completes — surge is reduced. For L = 2,000 m, a = 1,000 m/s: Tc = 4 seconds. Valve must close over ≥4 seconds for slow-closure surge reduction.
What surge protection devices are covered in this spreadsheet?
The spreadsheet sizes: air vessels (surge tanks) with polytropic gas law sizing (Graze method per CIRIA C680), one-way surge tanks (suction-side), flywheel inertia check, and pump bypass check valves (non-return valve slam suppression). Outputs include maximum and minimum envelope pressures along the pipe.
What’s Included
An instant Excel download with the complete formula set, a worked numerical example, and reference to the governing standard — ready to adapt to your own project inputs.
