by Grant Lobdell

According to the 2020 edition of National Fire Protection Association 25 Standard for the Inspection, Testing, and Maintenance of Water Based Fire Protection Systems, “Except as permitted by and, all antifreeze systems shall utilize listed antifreeze solutions.”  The exceptions in and are for systems installed prior to September 30, 2012, and systems utilizing premixed antifreeze solutions exceeding 30% (by volume) propylene glycol that are listed specifically for use with the installed ESFR sprinklers.  The exception regarding systems installed prior to September 30, 2012 ends September 30,2022.  At that time, any system utilizing premixed antifreeze solutions that are not listed must be drained and installed with a listed alternative.  If a listed antifreeze solution is not available or the listed antifreeze solutions that are available are not sufficient for the application, alternative means of freeze protection, such as dry sprinklers or heat tracing, must be used.

As of August 2020, there are two listed antifreeze solutions for use in fire sprinkler systems by Underwriters Laboratories (UL): Tyco’s LFP Antifreeze (Figure 1) and Lubrizol’s freezemasterTM Antifreeze (Figure 2).

Figure 1: Tyco’s LFP® Antifreeze UL listing.

Figure 2: Lubrizol’s freezemasterTM Antifreeze UL listing.

Tyco’s LFP® Antifreeze, which was the first listed antifreeze solution for use in fire sprinkler systems by UL and is for use down to -10°F, is composed of 49.35% glycerol (by weight) according to US Patent US10046191B1.  According to Tyco’s technical datasheet, this listed antifreeze solution is described as colorless in appearance and has a refractive index and specific gravity of 1.3960-1.3995 and 1.122-1.129, respectively.

Lubrizol’s freezemasterTM Antifreeze is for use down to -12°F and is being marketed as having superior corrosion resistance. It is composed of 20-30% glycerin (by weight) according to Lubrizol’s technical datasheet and  is described as clear blue in appearance with a refractive index and specific gravity of 1.390 and 1.088, respectively.

NFPA 25 requires the antifreeze solution be tested at least annually to ensure continued performance.  Testing of antifreeze solution can be done on site with a portable refractometer or hydrometer or at a laboratory such as Dyne Fire Protection Labs.  A significant change in the refractive index or specific gravity of the antifreeze solution should trigger replacement.  Dyne Fire Protection Labs is currently developing analysis techniques to differentiate these listed antifreeze solutions from non-listed alternatives.  Both listed antifreeze solutions contain other ingredients in addition to glycerin that aid in solution stability and/or corrosion resistance.  Testing to differentiate these solutions will involve identifying these ingredients.

If you have any questions regarding this article, please contact Dyne Fire Protection Labs at or (800) 632-2304.

©Dyne Fire Protection Labs 2020