Associated Fire Protection

Antifreeze loops protect areas in a building that are prone to freezing. A check valve isolates the antifreeze loop from the rest of the sprinkler system. There is also a main drain and a fill cup to assist in the draining and refilling of the loop. Antifreeze loops are filled with a variety of different liquids the most common being: propylene glycol, glycerin and ethylene glycol. If the sprinkler system is connected to a public water supply ethylene glycol should not be used because it is considered poisonous. Also, systems that are constructed out of CPVC plastic pipe should only be filled with glycerine. AFP has a policy only to use glycerine due to environmental and practical concerns. NFPA requires the testing of antifreeze loops on an annual basis.