Centrifugal Water Chiller : steel spring with limit stop housing and minimum static deflation of 1 " Cooling Towers : minimum static deflation of 2" Pumps : minimum static deflation of 1 " Air Handling Unit : minimum static deflation of 1 " (blower only) Centrifugal Roof Ventilators : Rubber-In-Sheer (Neoprene) and minimum static deflation of 1 " Centrifugal In-Line Fans (Hung Type) : Steel Spring Hanger w/ neoprene-in-sheer element and minimum static deflation of 1.25 " "Centrifugal Fans (floor mounted) : Steel Spring w/ limit stop housingand minimum static deflation of 1 """