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The Latest in Antifreeze Sprinkler Systems
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Issue 59: The Latest in Antifreeze Sprinkler Systems

By William Koffel, P.E., FSFPE

In August 2010, three Tentative Interim Amendments (TIAs) were issued by the NFPA Standards Council to prohibit the use of antifreeze in new automatic sprinkler systems protecting dwelling units.1,2,3 The TIAs applied to all three sprinkler standards: NFPA 13,4 NFPA 13D,5 and NFPA 13R.6 The initial action was considered conservative, and the National Fire Protection Association's Standards Council directed the respective technical committees to address the issue further and determine a position regarding antifreeze systems based upon the information available from recent fire tests. The Standards Council also indicated that the technical committee responsible for NFPA 257 needed to review the information and determine the appropriate course of action. In addition, the Standards Council noted that the action did not address the use of antifreeze solutions in systems protecting other than residential occupancies.

Based upon the recommendation of the respective technical committees, four additional TIAs were issued for NFPA 13,8 NFPA 13D,9 NFPA 13R,10 and NFPA 2511 in March 2011. The second round of TIAs superseded the previously issued TIAs on NFPA 13, NFPA 13D, and NFPA 13R and were based upon full scale fire tests conducted using residential sprinklers.12 The full-scale fire tests resulted in a number of changes to the standards. These changes included:

  • Requiring the use of premixed antifreeze solutions
  • Restricting the antifreeze solutions that may be used
  • Limiting the concentration of antifreeze to be used
  • Restrictions were also imposed on existing systems based upon the revisions to NFPA 13D and NFPA 25.

A subsequent TIA was later issued on NFPA 25 to address antifreeze solutions involving ESFR sprinkler systems.13 The Standards Council decision regarding these four TIAs highlighted the need for research on antifreeze solutions used in non-residential sprinkler systems, and subsequently a Fire Protection Research Foundation project was conducted to investigate antifreeze solutions supplied through spray sprinklers.

Based upon a review of an interim report on antifreeze systems using spray sprinklers, the Standards Council directed the respective Technical Committees to further review the information available and to submit additional TIAs as determined appropriate.15 The further review resulted in one additional TIA for NFPA 2516 and revisions to the 2013 editions of NFPA 13, NFPA 13D, and NFPA 13R.

Based upon the testing performed, the 2013 Editions of NFPA 13and NFPA 13R will not permit antifreeze solutions to be used in new sprinkler systems, either in residential or nonresidential applications, unless an antifreeze solution is specifically listed for use in such systems. At the time this article was written, no such listed antifreeze solutions exist, although at least one solution is being evaluated.

For new systems, the 2013 edition of NFPA 13D will permit the use of glycerine to a maximum concentration of 48% by volume and propylene glycol to a maximum concentration of 38% by volume in specific areas of dwelling units where acceptable to the authority having jurisdiction. NFPA 13D will permit the use of glycerine to a maximum concentration of 50% by volume and propylene glycol to a maximum concentration of 40% by volume for existing sprinkler systems.

Existing Systems

Although the decision to restrict the use of antifreeze solutions in new sprinkler systems was not taken lightly, the committee discussions noted that several alternatives could be considered when evaluating new systems. However, the committees responsible for NFPA 13D and NFPA 25 needed to give further consideration to the impact on existing sprinkler systems.

For systems protecting one- and two-family dwellings, the 2013 edition of NFPA 13D requires the antifreeze solution to be premixed. Permitted solutions are limited to:

  • Glycerine to a maximum concentration of 50% by volume
  • Propylene glycol to a maximum concentration of 40% by volume
  • Solutions specifically listed for use in fire protection systems

For all other sprinkler systems for which compliance with NFPA 25 is required, there are several options provided regarding existing systems. The use of an antifreeze solution specifically listed for use in fire protection systems will be required effective September 30, 2022. In the meantime, if all of the following criteria are met, existing antifreeze systems may remain in service:

  • The concentration of the antifreeze solution shall be limited to 50% glycerin by volume or 40% propylene glycol by volume.
  • Newly introduced solutions shall be factory premixed antifreeze solutions (chemically pure or United States Pharmacopoeia 96.5%).
  • Antifreeze systems with concentrations in excess of 30% propylene glycol and 38% glycerine shall be permitted based upon an approved risk assessment.

The provision permitting premixed antifreeze solutions of propylene glycol exceeding 30% concentration by volume will continue to be permitted for use with ESFR sprinklers where the ESFR sprinklers are listed for such use in a specific application.

In determining the criteria for existing systems, the committee sought to continue to allow existing systems provided they were considered to be reasonably safe. The TIA16 includes an allowance permitting the use of lower concentrations of 30% propylene glycol and 38% glycerine without a risk assessment. This provision which was developed based upon information available from Material Safety Data Sheets (MSDS) and testing performed by Factory Mutual.17

The original proposed TIA included an allowance to permit concentrations up to 50% glycerin by volume and 40% propylene glycol by volume in certain light hazard applications and in dwelling units protected with fast response sprinklers. However, the exceptions to the risk assessment were deleted by the Standards Council since there is a possibility for fires to occur with a heat release rate in excess of 1.4MW prior to sprinkler activation.

It should be noted that the required risk assessment is a "deterministic risk assessment" - meaning that one must assume a fire occurs and therefore a low probability or likelihood of a fire occurring may not be used to substantiate a higher concentration of antifreeze. The risk assessment should use the data available from full scale fire tests (many of which are referenced herein), the occupancy of the space, the type of sprinkler installed, the ceiling height, and the potential heat release rates for reasonably credible fire scenarios. There may be some additional considerations for unoccupied spaces such as the risk posed to adjacent spaces. At the time of writing this article, an additional proposed TIA has been submitted for NFPA 25 and is available for Public Comment (TIA Log No. 1077). The additional TIA provides some additional clarification as to what should be included in the risk assessment.

William Koffel is with Koffel Associates

  1. TIA 10-1, NFPA 13, Standard for the Installation of Sprinkler Systems, National Fire Protection Association, Quincy, MA, 2010.
  2. TIA 10-1, NFPA 13D, Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes, National Fire Protection Association, Quincy, MA, 2010.
  3. TIA 10-1, NFPA 13R, Standard for the Installation of Sprinkler Systems in Low-Rise Residential Occupancies, National Fire Protection Association, Quincy, MA, 2010.
  4. NFPA 13, Standard for the Installation of Sprinkler Systems, National Fire Protection Association, Quincy, MA, 2010.
  5. NFPA 13D, Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes, National Fire Protection Association, Quincy, MA, 2010.
  6. NFPA 13R, Standard for the Installation of Sprinkler Systems in Low-Rise Residential Occupancies, National Fire Protection Association, Quincy, MA, 2010.
  7. NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, National Fire Protection Association, Quincy, MA, 2011.
  8. TIA 10-2, NFPA 13, Standard for the Installation of Sprinkler Systems, National Fire Protection Association, Quincy, MA, 2010.
  9. TIA 10-2, NFPA 13D, Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes, National Fire Protection Association, Quincy, MA, 2010.
  10. TIA 10-2, NFPA 13R, Standard for the Installation of Sprinkler Systems in Low-Rise Residential Occupancies, National Fire Protection Association, Quincy, MA, 2010.
  11. TIA 11-1, NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, National Fire Protection Association, Quincy, MA, 2011.
  12. Code Consultants, Inc., Antifreeze Solutions in Home Fire Sprinkler Systems, Phase II Research Final Report, Fire Protection Research Foundation, Quincy, MA, 2010.
  13. TIA 11-2, NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, National Fire Protection Association, Quincy, MA, 2011.
  14. Fire Protection Research Foundation, "Antifreeze Solutions Supplied through Spray Sprinklers: Interim Report” Fire Protection Research Foundation, Quincy, MA, 2012.
  15. Standards Council Decision D#12-2, Decision on Council Agenda Item 12-3-8 on antifreeze issue, National Fire Protection Association, Quincy, MA, March 6, 2012.
  16. TIA 11-3, NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, National Fire Protection Association, Quincy, MA, 2011.
  17. "K-25 Suppression Mode Sprinkler Protection for Areas Subject to Freezing," FM Technical Report J.L.0003004619, FM Global, Norwood, MA, 2010.

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