Instantly save you 63% Off. Watts Series 15 Water Hammer Arrestor 1/2" (0750030) Watts Series 15 Water Hammer Arrestors for Controlling Water Pressure Shock. Used in Commerical and Industrial Applications. The noise from banging pipes is caused by shocks of high speed water flowing in the piping system when a fixture is suddenly closed. Sudden stoppage of the water (a non-compressible liquid) flowing at a given pressure and velocity causes a surge or spike of water and is called water hammer. When this occurs a pressure wave travels back through the piping until it finds a poin  ...More Details