WORLD FOR CIVIL

Water Hammer

Water hammer is a change in pressure, either above or below the normal pressure, caused by a variation of the flow rate in a pipe.

The equation for the velocity of a wave in a pipe is

U=?(E/?)?[1/(1+ED/E_pt)]

where

U =velocity of pressure wave along pipe, ft /s (m/s)

E =modulus of elasticity of water, 43200000 lb/ft²
(2070000 kPa)

D =diameter of pipe, ft (m)

E_p =modulus of elasticity of pipe material, lb/ft²
(kg/m²)

t =thickness of pipe wall, ft (m)