Fire sprinkler systems put out or slow the growth of fires by drenching them and the surrounding area with water, removing heat and potential fuel sources. Water mist systems work by cooling the room temperature and displacing oxygen with steam. Both systems use water but in different ways. The key difference is the size of the water droplets.
Water mist systems have droplets with a diameter less than 1,000 microns each, according to the National Fire Protection Association (NFPA). That is basically a fifth of the size of the droplets made by standard fire sprinkler system. This allows a water mist system to spray large numbers of tiny droplets over a large water surface area that can lower temperatures. When these tiny droplets meet hot air, they evaporate and turn to steam. Steam can absorb more heat per unit of time than larger water droplets which causes the temperature of the flames to decrease faster. Steam will also displace the oxygen in the room so that the fire is suffocated and extinguished.
All water mist systems create fine sprays using water. They can be divided into three types: low-pressure systems, intermediate-pressure systems, and high-pressure systems. Low pressure systems have pressures of 175 PSI or less, like standard fire sprinkler systems. Intermediate-pressure systems have 175 – 500 PSI, while high-pressure systems exceed 500 PSI.
Here are some of the differences between water mist and fire sprinkler systems:
- Water mist systems may have single or multiple orifices, while sprinklers only have one.
- Fire sprinklers discharge only water or water with additives. Water mist sprinklers may discharge additives, air, and various gas agents.
- Sprinkler systems suppress fires primarily by wetting the fuel surface. Water mist systems use fast water droplet vaporization, which leads to cooling, air displacement, air/fuel vapor dilution and heat radiation attenuation, along with wetting of the fuel surface.
- The water droplets are less than 1000 microns in 99% of the water mist system while fire sprinkler systems have no limitation on droplet size.
- Water mist systems do less damage and are easier to clean up than fire sprinkler systems.
There are many differences between water mist and fire sprinkler systems but they both put out fires. Call Fire Control Systems today to help you decide which system is best for you.
