One of the roles of NFPA staff engineers is to answer technical questions from our members. The other day I got a call from a member who simply said "So, antifreeze...where are we at?". That simple 4-word question lead to an hour long discussion on the recent history on antifreeze use in sprinkler systems. Not more than an hour later I received a similar call from a member trying to figure out where "we" stand.
The simple answer is that at the moment is following the guidance of a Tentative Interim Amendment (TIA) approved by the Standards Council in March 2011(TIA 13-10-2) is in effect on the 2010 edition of NFPA 13. This TIA limits the concentrations of antifreeze solutions in new systems to 48% glycerine and 38%propylene glycol. It also requires that all solutions must be factory premixed to avoid separation of the solution, leaving pure (100%) antifreeze to be trapped in certain portions of the system.
Following the issuance of this TIA, which was based on testing that considered residential sprinklers only, the Fire Protection Research Foundation, along with UL and CCI, conducted another testing program utilizing standard spray sprinklers. The results of this testing showed that concentration allowances set forth in the March 2011 TIA may not be appropriate for use with standard spray sprinklers in all arrangements. This lead the Technical Committee (TC) for Sprinkler System Installation Criteria to draft a new TIA to modify the allowances for the use antifreeze in new NFPA 13 sprinkler systems. Due to the uncertainty of how traditional antifreeze solutions/concentrations will respond to the myriad of potential arrangements (ceiling height, k-factor, pressure, fire size..etc), the TC is suggesting that only antifreeze solutions that are listed should be used in sprinkler systems. The listing process would then need to flush out solutions that have the potential to ignite when discharged from a sprinkler. This proposed TIA, along with TIAs on NFPA 13R, 13D and 25 dealing with antifreeze will be addressed at the upcoming August Standards Council meeting.