# Water Hammer Inlet Pressure

on . Posted in Fluid Dynamics

Water hammer refers to the sudden increase in pressure that occurs when a fluid is forced to stop or change direction suddenly.  This can occur in piping systems when the flow of water is abruptly halted or redirected, causing a shock wave that travels through the pipes.  Water hammer inlet pressure is the pressure at the inlet of a system or pipe where water hammer occurs.  The inlet pressure is the pressure of the fluid entering a particular section of the piping system.

Water hammer is a concern in plumbing and fluid transport systems because it can lead to pressure spikes that may damage pipes, valves, and other components of the system.  Proper design, including the use of pressure relief devices and surge suppressors, is used to minimize the risk of water hammer and its potential consequences.  Understanding the inlet pressure is used for assessing the conditions that contribute to water hammer events and implementing appropriate measures to prevent or mitigate them.

### Water Hammer Inlet Pressure Formula

$$p_i \;=\; 0.070 \;v \; l \;/\; t$$     (Water Hammer Inlet Pressure)

$$v \;=\; p_i \; t \;/\; 0.070 \; l$$

$$l \;=\; p_i \; t \;/\; 0.070 \; v$$

$$t \;=\; 0.070 \;v \;l \;/\; p_i$$

Symbol English Metric
$$p_i$$ = inlet pressure  $$lbf\;/\;in^2$$ $$Pa$$
$$v$$ = flow velocity $$ft\;/\;sec$$ $$m\;/\;s$$
$$l$$ = upstream pipe length $$ft$$ $$m$$
$$t$$ = valve closing time $$sec$$ $$s$$

Tags: Water Hammer