Description
N.F.P.A. 13, 13D and 13R requires the use of an expansion chamber on antifreeze systems with backflow preventers. The TrimFit ET25 is a rubber bladder filled expansion chamber designed for use on antifreeze based fire sprinkler systems. It has been tested and U.L. listed to be compatible with both propylene glycol and glycerin based antifreeze. The expansion chamber regulates pressure caused by thermal expansion and contraction within the closed system.