Why is the solution in anti-freeze loops on automatic sprinkler systems being reformulated?

May 11, 2022

by Nils Deacon, Manager, Inspections and Rating Services

Anti-freeze loops and systems used general solutions containing glycerin and propylene glycol for many years. In 2009, there were instances where the discharge of the fluid appeared to have contributed to the fire spread and intensity. Certain concentrations of the anti-freeze were actually intensifying the fires they were meant to control.

Underwriters Labs (UL) produced UL 2901 (The Outline of Investigation for Anti-freeze Solutions for Use in Fire Sprinkler Systems) to specifically study the problem.

UL and NFPA worked together to revise their standard language to require safer anti-freeze systems. In 2013 the standards called for anti-freeze solutions used in sprinkler systems to be UL Listed and Certified. Furthermore, by 9-30-22, glycerin and propylene glycol solutions will be completely phased out in favor of the VDUB UL listed anti-freeze solution.

DISCLAIMER: This information reflects the interpretation of MSO, Inc. with regard to NFPA Standards and Codes. It does not represent NFPA’s official position on the items discussed.

Anti-freeze system