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Fire Sprinkler System Antifreeze Dangers Led to NFPA 25 Revisions

By: Mark Knurek on September 27th, 2019

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Fire Sprinkler System Antifreeze Dangers Led to NFPA 25 Revisions

Codes, Standards & Approvals  |  Temperature

NFPA 25 is the standard for the inspection, testing and maintenance of water-based fire protection systems. While not a legal requirement, per se, it is regarded as the industry’s guide to best practices. Many authorities having jurisdiction (AHJs) require strict adherence to NFPA 25 – and frankly, there is no reason not to design, repair or maintain a system to the standard.

The standard is updated on a regular basis, with the most recent edition published in 2017. In 2014, NFPA published emergency changes regarding the use of antifreeze. Let’s take a look into the background of what prompted this requirement and why it is so important to use an antifreeze that meets UL requirements.

Water-filled pipes for fire sprinkler systems, such as those made of metal or CPVC, must remain above 40 F/4.44 C to prevent freezing that can cause severe damage, leaks or pressure drops. Glycerin and propylene glycol-based antifreeze solutions had been the industry standards for many years to prevent freezing, thus allowing the systems to protect lives and property despite severe cold, particularly in northern climes. While both are combustible agents, they have been seemingly used effectively as long as the proportion mixed with water was at levels prescribed by the manufacturer.

That way of thinking changed forever when a 2009 cooking fire was intensified – rather than suppressed – by a sprinkler system equipped with glycerin-based antifreeze, killing a young mother and injuring her husband and three children. The antifreeze concentration was extremely high, estimated at 71.2 percent, causing the fire to virtually explode. The news of this fire caused some municipalities to ban the use of antifreeze.

A 2001 New Jersey resort fire was described similarly, with injuries to 16 people. An excessive proportion of propylene glycol-based antifreeze in the sprinkler protection system was the presumed cause.

In both instances, the high percentage of antifreeze solutions was likely caused by improper mixing on-site when installed in the fire sprinkler system.


NFPA and UL Research Results in New Standards for Antifreeze

Following the 2009 fire, NFPA and Underwriter’s Laboratories (UL) conducted extensive research that showed certain concentrations of antifreeze would actually intensify a fire.

Based on the research, UL established standard UL 2901 in December 2013. The standard outlines requirements for the performance of antifreeze solutions for wet pipe fire sprinkler systems. To meet the UL 2901 requirements, antifreeze products must prove corrosion resistance (important for metal-based fire sprinkler systems), fire performance (i.e., flammability - an especially challenging performance requirement to meet), low conductivity levels, hydraulic characteristics, human health and environmental impact, and marking and installation specifications.

Following the establishment of UL 2901, in January 2014, the NFPA enacted emergency changes to NFPA 25, Inspection, Testing and Maintenance of Water-Based Fire Protection Systems, regarding the use of antifreeze solutions. The revisions were based on the earlier NFPA/UL research and UL 2901.

Bottom line, NFPA 25 states that all new antifreeze systems must use premixed antifreeze solution meeting UL requirements, which indicates the solution will not ignite when discharged from a sprinkler.

Exceptions to this include glycerin and propylene glycol (aka, traditional) antifreeze products used in installed sprinkler systems prior to September 30, 2012, where the following condition is met:

  • The concentration of the antifreeze solution shall be limited to 30% propylene glycol and to 38% glycerin by volume or
  • Antifreeze systems with concentration in excess of 30% but not more than 40% propylene glycol by volume and 38% but not more than 50% glycerin by volume shall be permitted where approved by the AHJ, providing substantiating documentation is provided or
  • The continued use of factory premixed propylene glycol in excess of 30% by volume for early suppression, fast response (ESFR) systems, where the ESFR sprinklers are listed for such use in a specific application (i.e., systems installed in warehouses in place of in-rack systems)

These solutions may no longer be used after September 29, 2022. These products must be replaced by a premixed solution meeting the requirements of UL 2901 after that date.

Rigid standards and annual testing methods were also established for existing systems, allowing specific levels of factory premixed antifreeze solutions. These levels varied among NFPA 13, NFPA13D and NFPA 13R systems.

One term of which to take note in all of the NFPA revisions: the use of factory premixed antifreeze solutions. The factory premixed requirement takes the guesswork and potential risk out of onsite mixing.


freezemasterTM Antifreeze For All Wet Fire Sprinkler Systems

Lubrizol Advanced Materials, a specialty company with more than 30 years of fire safety expertise, is proud to announce the availability of freezemasterTM antifreeze – a breakthrough antifreeze that remains in a protective liquid state at the lowest temperature of any antifreeze that meets NFPA requirements for all new antifreeze

systems and provides for the future requirement that existing systems must have an antifreeze meeting NFPA requirements installed by September 30, 2022.

freezemasterTM antifreeze delivers the safety, performance and assurance you can rely on in temperatures as low as -17 F/-27 C.

freezemasterTM antifreeze’s temperature threshold is not its only unique attribute. It also:

  • Provides superior corrosion resistance compared to other available antifreeze solutions
  • Is colored blue for easy visual verification of complete flush
  • Is backed by a team of product specialists who are on call to provide onsite and technical support

We look forward to telling you more about freezemasterTM antifreeze in future blog posts. In the coming weeks, we’ll tell you more about the rigid requirements of UL 2901 – specifically about fire performance, corrosion resistance and the importance of temperature thresholds. Subscribe today to our blog to stay up-to-date with the latest industry and product information.

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