In an NFPA Journal column Matt Klaus, Senior Fire Protection Engineer at NFPA, answers questions about the new Tentative Interim Amendments (TIAs) that were issued at the August 2012 meeting of the Standards Council addressing requirements and alternatives to antifreeze solutions in fire sprinkler systems.
Matt explains that the NFPA technical committees responsible for writing NFPA 13, NFPA 13R and NFPA 13D created new requirements that mandate the use of “listed” antifreeze solutions for new system designs. The critical component of the listing is that it needs to indicate that the solution will not ignite when discharged from a sprinkler, essentially prohibiting the use of propylene glycol and glycerin, which are not listed.
Matt tell us that for new NFPA 13D systems in single family homes the AHJ may approve a traditional solution, glycerin or propylene glycol at a specified limit, provided that documentation is submitted by the designer showing why it is acceptable. For existing NFPA 13D systems the old rule from the March 2011 TIA are still in play and existing systems will be permitted to use propylene glycol and glycerin at the limits established in the TIA.
Other alternatives to antifreeze solutions include insulation or heaters. Insulating sprinkler piping runs in walls, interstitial spaces, and attics is common in wood-framed buildings, especially where NFPA 13R and NFPA 13D systems are installed. Matt reminds us that it is important to install the insulation so it cannot be easily altered, compromising its thermal resistance properties and potentially leading to frozen pipes. This is fairly easy to accomplish in walls and concealed spaces where there is limited access, but it can be trickier in attics.