Surge chamber

From GAWDAwiki

A surge chamber is a chamber or tank connected to a pipe at or near a valve that quickly opens and closes, or a pump that may suddenly start or stop. When the flow of water in a pipe starts or stops quickly, the surge chamber allows water to flow in or out, minimizing any sudden positive or negative pressure waves or surges in the pipe.^[1]

References

1. http://www.owp.csus.edu/training/glossary/s/surge_chamber_.php