# Water Hammer Valve Closing Time

on . Posted in Fluid Dynamics

Water hammer valve closing time, also called closing time of a valve, is the duration it takes for a valve to fully close.  The time it takes for a valve to close can vary depending on the type of valve, its size, the operating conditions, and the control system used to operate it.  Water hammer is a hydraulic shock or pressure surge that occurs in a fluid system when there is a sudden change in the flow velocity of the fluid.  This change in velocity can happen when a valve is rapidly closed, causing a sudden stoppage of the fluid flow.

In water hammer, the valve closing time is a critical factor.  If a valve is closed too quickly, it can lead to a rapid change in flow velocity, which in turn can generate high pressure waves within the fluid.  These pressure waves can travel through the system, causing damage to pipes, fittings, and other components.  In extreme cases, water hammer can even result in pipe rupture.

To mitigate water hammer and its potentially damaging effects, engineers and operators may use various techniques and equipment, such as valve closing time control systems, slow-closing valves, or hydraulic surge arrestors.  These methods aim to slow down the rate at which the valve closes, reducing the abrupt change in flow velocity and minimizing the risk of water hammer.

### Water Hammer valve closure time Formula

$$WH_{vc} \;=\; \rho \; v \;/\; t$$     (Water Hammer Valve Closure Time)

$$\rho \;=\; WH_{vc} \; t \;/\; v$$

$$v \;=\; WH_{vc} \; t \;/\; \rho$$

$$t \;=\; \rho \; v \;/\; WH_{vc}$$

Symbol English Metric
$$WH_{vc}$$ = water hammer valve closure time $$lbf\;/\;in^2$$ $$Pa$$
$$\rho$$ (Greek symbol rho) = density of fluid $$lbm\;/\;ft^3$$ $$kg\;/\;m^3$$
$$v$$ = velocity of fluid $$ft\;/\;sec$$ $$m\;/\;s$$
$$t$$ = valve closure time $$sec$$ $$s$$

Tags: Water Hammer Valve