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Antifreeze Explained
Christian Dubay, NFPA’s vice president of Codes and Standards and chief engineer, on the process that led to NFPA prohibiting the residential use of antifreeze solutions
NFPA Journal®, November/December 2010
By Christian Dubay
In August, NFPA’s Standards Council voted to prohibit the use of antifreeze solutions in new residential fire sprinkler systems designed in accordance with NFPA 13D, Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes, and NFPA 13R, Installation of Sprinkler Systems in Residential Occupancies up to and Including Four Stories in Height, and within the dwelling unit areas for new fire sprinkler systems designed in accordance with NFPA 13, Installation of Sprinkler Systems. The Council issued Tentative Interim Amendments (TIAs) for NFPA 13, NFPA 13D, and NFPA 13R, all prohibiting the use of antifreeze solutions in new fire sprinkler systems until further action from the NFPA technical committees.
When reviewing the issues surrounding antifreeze solutions and automatic fire sprinkler systems, two points should be made immediately. First, 80 percent of fire fatalities occur in the home, and when home fire sprinklers are present, the risk of dying in a home fire decreases by 80 percent. NFPA strongly supports and urges the expanded use of residential fire sprinkler systems as the most effective way to prevent fire injuries and deaths in the home and other residential occupancies. Second, where existing fire sprinkler systems utilize antifreeze solutions, in no case should these systems be disconnected.
Historically, automatic fire sprinkler systems with antifreeze solutions have had a successful track record for more than 60 years, and they’ve had an equally successful track record since they’ve been allowed within residential applications. Earlier this year, however, NFPA became aware of a fire incident involving a fire sprinkler system in an apartment that contained a high concentration of antifreeze solution. This raised concerns about the combustibility of antifreeze solutions in fire sprinkler systems. This specific incident involved a grease cooking fire in the kitchen where the fire sprinkler system had a reported antifreeze concentration of 71.2 percent. The fire resulted in a single fatality and serious injury to another person. Recently, NFPA received a report of another incident, this time involving a living room fire, which may have been exacerbated by the presence of an antifreeze solution in the sprinkler system.
As soon as NFPA became aware of the initial incident, we presented the fire incident report and data to the Technical Correlating Committee for Automatic Sprinkler Systems. Out of that committee meeting, a task group of the correlating committee was formed and developed an initial action plan to complete an initial research project with the Fire Protection Research Foundation (FPRF), which involved a literature study and a review of the data that is known about antifreeze solutions and fires. Independent of the FPRF activities, Underwriters Laboratories (UL) initiated full-scale testing to evaluate the potential flammability of antifreeze solutions as documented in the fire. While the results of the initial research by the FPRF and UL showed that there was potential for flash fires associated with various concentrations of antifreeze solutions, there was not enough information to come to a final conclusion about the permitted use and application of antifreeze solutions in fire sprinkler systems. A phase-two research project was initiated to complete a full-scale fire test program to evaluate different concentrations of antifreeze solutions, varying pressures, and various sprinkler arrangements and orientations. In addition, NFPA issued its initial alert bulletin in July, recommending as an interim step that residential fire sprinkler systems containing antifreeze be drained and refilled with water until such time as better data and guidance are developed.
The second-phase research was completed in August. In addition to the extensive fire-test data that was generated, we have learned five key points as a result of the project. First, antifreeze solutions with concentrations of propylene glycol exceeding 40 percent and solutions of glycerin exceeding 50 percent have the potential to ignite when discharged through automatic fire sprinklers. Second, antifreeze solutions of propylene glycol exceeding 40 percent and glycerin exceeding 50 percent are not appropriate for use in residential fire sprinkler systems. Third, antifreeze solutions of 40 percent propylene glycol and 50 percent glycerin demonstrated similar performance to that of water alone for fire control throughout the series of fire tests. Fourth, where antifreeze solutions are utilized in existing systems, consideration should be given to reducing the acceptable concentrations of these antifreeze solutions by an appropriate safety factor; technical committee deliberations are under way to determine what the appropriate safety factor should be. Finally, where utilized in existing systems, any antifreeze solution should only be a factory pre-mixed solution.
These findings led the NFPA Standards Council to issue the three TIAs prohibiting the use of antifreeze solutions in sprinkler systems in new residential construction and dwelling units and portions of other occupancies, and to seek specific input and guidance on the application and use of the data from the NFPA Technical Committees. In addition, NFPA issued an updated Alert Bulletin in August to summarize the data from the research project and to provide guidance for existing fire sprinkler systems that utilize an antifreeze solution.
NFPA guidance
While NFPA sprinkler standards are installation standards and do not currently address the problem of antifreeze in existing sprinkler systems, NFPA is providing guidance for installed automatic sprinkler systems using antifreeze solutions. Our first recommendation, as stated earlier, is to not disconnect any system that utilizes antifreeze, since an automatic sprinkler system remains an extremely effective method of controlling a fire and preventing injury and death. However, if you are responsible for automatic fire sprinkler systems, or have such a system, you should contact your sprinkler contractor to determine if there is an antifreeze solution in your system. If there is, you should first determine if there are other means, such as insulation, that can be utilized to provide adequate freeze protection in lieu of an antifreeze solution.
Where there is no viable alternative to an antifreeze solution, NFPA recommends that you only use factory premixed propylene glycol or glycerin antifreeze solutions, and that they be added in the lowest possible concentrations required to prevent freezing. Under no circumstances should antifreeze solutions in existing systems exceed a maximum concentration of 40 percent propylene glycol or 50 percent glycerin. The antifreeze solution should only be a factory premix solution, which is essential to ensure the proper concentration levels and for solution integrity. Finally, any use of an antifreeze solution in existing fire sprinkler systems should only be utilized with the approval of your local authority having jurisdiction.
In addition to issuing the TIAs, the Standards Council provided feedback to the automatic sprinkler systems and maintenance technical committees. Specifically, the Council asked for three areas to be addressed and reported back to the Council. The first is for the technical committees to review all of the appropriate technical data to determine if new proposed technical changes can be developed and technically substantiated to address the use of antifreeze solutions in new systems. Second, the committees need to review what technical requirements can be developed and substantiated to address the use of antifreeze solutions in existing fire sprinkler systems. Finally, the technical committees are reviewing the use and application of antifreeze solutions in all occupancies, as the fire-test data and some of the historical fire data indicated that the fire problem is directly associated with the solution and not the specific occupancies. It is anticipated that the Technical Correlating Committee on Automatic Sprinkler Systems will report its findings and next steps to the Standards Council at its October meeting.
In order to keep the public up to date on all actions and activities around the use of antifreeze solution in fire sprinkler systems, NFPA has established a website dedicated to the issue. For more information, including all of the relevant fire-test data, NFPA Alerts, and Tentative Interim Amendments, visit nfpa.org/antifreeze.
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