FireFighter GL freeze protection fluid, Noble Co.’s antifreeze for wet fire sprinkler systems, is a glycerin-based solution for systems made from CPVC and metallic pipe. The company’s FireFighter PG is a propylene glycol for most metallic pipe systems. These fluids are available in 5-gal. containers, 55-gal. drums, totes or tank trucks and are produced in concentrations which meet NFPA guidelines for factory premixed antifreeze solutions. Custom blends also are available.