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|The Latest in Antifreeze Sprinkler Systems|
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 The second round of TIAs superseded the previously issued TIAs on NFPA 13, NFPA 13D, and NFPA 13R and were based upon full scale fire tests conducted using residential sprinklers.12 The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:
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
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.
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:
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 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
William Koffel is with Koffel Associates
2nd Quarter 2012 - Challenges for the Fire Sprinkler Industry -- Kenneth E. Isman, P.E., FSFPE
2nd Quarter 2012 - NFPA 13 Sprinkler System Design Density Curves – Where Did They Come From? -- Garner A. Palenske, P.E.
4th Quarter 2010 - NFPA Issues Alerts on Antifreeze in Residential Sprinkler Systems
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