Full-scale burn testing has been conducted utilizing specific types of sprinkler systems, propylene glycol solutions and K 25.2 ESFR sprinklers that have been specifically tested for the application. The listings and manufacturer's installation instructions for these propylene glycol systems are very specific with regards to the type of system, the system volume and the piping configuration. If a system is selected to protect a cold storage occupancy using a propylene glycol solution, the fire protection designer must verify the appropriate product listings. In addition, the manufacturer's technical literature must be reviewed to ensure that the system design is in compliance with the listings and that all of the required components have been installed.
In addition to evaluating manufacturer's recommendations and the specific equipment required for these special sprinkler systems, the designer must approach the hydraulic calculation with the understanding that a liquid (other than water) will initially be moving through the piping network. Traditionally, when the fire protection designer is performing the hydraulic calculation for a sprinkler system in accordance with NFPA 13, the Hazen-Williams formula for determining the friction loss is adequate. However, because the propylene glycol solution is a much more viscous liquid than water, the system volumes are much larger than a traditional antifreeze loop, and the cold storage environment may experience sustained temperatures as low as -20°F, the Darcy-Weisbach formula must be used in one of the two required hydraulic calculations for systems utilizing propylene glycol solution.