Fire Fighting Characteristics of Water Mist Systems

Fire Fighting Characteristics of Water Mist Systems

Did You Know…water mist systems have these contributing fire fighting characteristics?

  • Cooling Effect:  Water mist absorbs heat from flames.
  • Inert Effect:  Water evaporates to steam at the flame and heat source which results in the dilution of the surrounding oxygen and fuel vapors.
  • Smaller is Better:  Smaller or finer water droplets are more efficient than larger water droplets.
  • 1 droplet VS. 1,000 droplets:  Dividing 1 water droplet into 1,000 smaller water droplets improves fire fighting performance.
  • Improve Fire Fighting Performance:  The range and diameter of water droplets pattern improves fire fighting performance.
  • Improve Fire Fighting Efficiency:  Higher pressure for propulsion of the water droplets improves water droplet penetration into the flame zone, improving fire fighting efficiency.

Traditional Sprinkler Droplet vs. Water Mist Droplet

The typical fire sprinkler droplet size is 1mm.  Water droplet sizes less than 1mm can be classified as misting water droplets.  Why is this information important?  Manufacturers can classify a system as a misting system, if the water droplet size is technically less than 1mm.  To really improve water-based system performance, water misting droplet sizes of 1/1000 the size of the typical sprinkler droplet substantially improves the effectiveness of water for fire protection.

Sprinkler droplet vs. Water Mist droplet

Why Does Size Matter?

Referring back to the characteristics of water:

Water absorbs heat (cooling factor).  The sprinkler water droplets surface area absorbs heat.  Let’s take a single sprinkler water droplet and divide it into 1,000 water droplets.  The result is a multiplication of water droplet surface area capable of absorbing heat faster.

Water evaporates to steam at the flame/heat source with the result of diluting the surrounding oxygen; thus depriving the fire of the needed oxygen to burn.

Smaller or finer water droplets are more efficient than larger water droplets.  Let’s revisit the single sprinkler water droplet example and divide it into 1,000 water droplets.  Once again, the multiplication of the droplets has increased the surface area of water at the fire (faster absorption of heat; improving cooling time).  Additionally, the smaller size of the water droplet lessens the time of water evaporation at the flame front, which increases the rate that oxygen is removed from the flame and heat source (improved inert effect).

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