The pressure rise due to water hammer depends upon:

Explanation:

Water Hammer

• Water hammer is the result of a rapid rise in pressure occurring in a closed piping system.
• It normally occurs as a result of sudden pump startup, stopping (or failing) or in the change in speed of a pump or the sudden opening or closing of a valve resulting in a change in water velocity in the system.
• A common example of a water hammer that takes place in most homes every day e.g., Simply turning off a shower quickly will send a loud thud through the house

The pressure rise due to water hammer depends upon:

• The velocity of the flow of water in pipe,
• The length of pipe,
• Time is taken to close the valve,
• Elastic properties of the material of the pipe.

The following cases of water hammer will be considered:

• Gradual closure of the valve,
• Sudden closure of valve when the pipe is rigid, and
• Sudden closure of valve when the pipe is elastic.

The time required for the pressure wave to travel from the valve to the reservoir and back to the valve is:

\(t = \frac{{2L}}{C}\)

Where:

L = Length of the pipe (m), C = Speed of pressure wave (m/s)

If the valve time of closure is t_c, then

• If \({t_c} > \frac{{2L}}{C}\) the closure is considered gradual.
• If \({t_c} \le \frac{{2L}}{C}\) the closure is considered sudden.