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Wastewater
Treatment Articles Index
When you close a valve on a water pipe quickly, the pressure can rise far above the working pressure. The result is water hammer. Damage to the pipes can occur.
A similar condition can occur in a sewage pump station. The discharge pipe on a sewage pump normally includes a check valve. The check valve has a flapper that automatically closes to prevent the water from flowing backwards when the pump shuts off. This check valve can close very quickly.
To mitigate water hammer caused by a check valve, the check valve may include a spring. The spring forces the check valve to close as the pump shuts off. The spring closes the valve, not the backflow of water. If the backflow of water closes the valve, water hammer can result. (An outside weight and lever is sometimes used instead of a spring.)
In the cases of long discharge pipe lines from the pumps, even a check valve with a spring may not be not sufficient to prevent serious water hammer. A motorized check valve may be needed to close slowly over a period of several seconds. A surge relief valve may also be used in certain situations.
Wastewater Treatment Articles Index
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