Water mist systems are becoming increasingly more popular as an alternative to traditional fire sprinkler systems but like any new technology we need to carefully understand its benefits and limitations and this is also true when we look at hydraulic calculations for such systems.

The best guidance for hydraulic calculations for use with low, intermediate and high pressure systems can be found in NFPA 750 which provides detailed guidance on velocity limitations, use of additives and the pressure loss formula which must be used. For many systems the traditional Hazen Williams pressure loss formula will not be adequate and should be changed to the more reliable Darcy Weisbach.

You have always been able to switch between these two pressure loss formulas in FHC but with the increased use of water mist systems and the complexities of knowing which pressure loss formula to use, Canute has updated its technical data sheet TDS #1 'Using FHC for water mist calculations'. This document explains NFPA 750 methodology for water mist hydraulic calculations and which pressure loss formula is suitable for the various types of system. It also shows how you can use this information within FHC software to your best advantage.

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