The WHS Series is a heavy duty water hammer arrestor used to protect plumbing lines from the destructive effectsof water hammer produced by solenoid or other quick closing valves, pulsations from reciprocating pumps, and absorption offluid line expansion, heavy equipment such as commercial laundry machines, dishwashers, etc . . . It is a pressure vesselcontaining an inner, expandable and collapsible stainless steel bellows assembly. A M.I.P. connection is provided to permit liquiddisplaced from the plumbing lines to enter the inside of the bellows assembly. Inside the pressure vessel and surrounding theoutside of the bellows assembly, nitrogen gas is sealed at a pressure equal to the line pressure so that under normal flowingconditions, the internal and external pressures on the bellows unit are equal. The housing is designed to allow for the expansionof the bellows within the shell as it absorbs surges from the main line flow, thus preventing excessive pressure and shock. AllWHS Series water hammer arrestors are welded to meet ASME unfired pressure vessel codes.