The 2014 edition of NFPA 25, the standard for the inspection, testing and maintenance of water-based fire protection systems, was written to specifically include emergency changes regarding the use of antifreeze. Those changes were based on events in which activated sprinkler systems, fortified with antifreeze, actually intensified blazes rather than extinguished them. This was likely due to onsite errors in mixing the solutions that introduced excessive amounts of the active ingredients glycerin and propylene glycol, both of which increase flammability when present in high concentrations.
UL 2901 was established in December 2013, outlining certification requirements for antifreeze solutions for wet pipe fire sprinkler systems. To meet the UL 2901 requirements, antifreeze products must meet corrosion resistance (important for metal-based fire sprinkler systems), fire performance (i.e., flammability), hydraulic characteristics, human health and environmental impact, and marking and installation specifications.
When a fire sprinkler system activated as designed in 2009 to suppress a cooking fire – and instead intensified the blaze, killing one and injuring four – the use of antifreeze in sprinkler systems changed forever. The sprinkler system contained antifreeze that had been mixed improperly before application. A high concentration of the antifreeze agent caused the flames to virtually explode when the sprinkler system activated.
NFPA 25 is the standard for the inspection, testing and maintenance of water-based fire protection systems. While not a legal requirement, per se, it is regarded as the industry’s guide to best practices. Many authorities having jurisdiction (AHJs) require strict adherence to NFPA 25 – and frankly, there is no reason not to design, repair or maintain a system to the standard.