Fire S.A.
Comprehensive Fire Protection Specialists
 The Chemistry of Fire
Basic knowledge of the chemistry of fire is necessary to understand how a product acts on the fire to accomplish fire suppression.
Historically, the chemistry of fire was based on the fire triangle.
In the early 1980s, a fourth leg, known as free radicals, was identified.
Today it is well documented that the chemistry of fire is based on the fire tetrahedron which consists of oxygen, fuel, heat, and the newly-emphasized fourth leg, the free radical.
For fire propagation to continue, all four components of the fire tetrahedron must be present.
Fire Suppression Mechanics
Fire suppression is accomplished through the elimination of one or more legs of the fire tetrahedron.
There are fundamental differences between the fire suppression mechanics of Wetting Agents (NFPA 18), Class A and B Foams (NFPA 1150 and NFPA 11), and F-500 Micelle Encapsulator Fire Suppression Agent Technology (NFPA New Project).
These differences are outlined and discussed below:
Wetting Agents
Wetting Agent Fire Suppression Mechanics rely on one main mechanism:
1. Reduction of Surface Tension -
The surface tension of water is reduced from 72 dynes/cm to less than 33 dynes/cm.
Surface tension reduction provides several fire suppression advantages over plain water.
 Surface tension reduction results in a smaller water droplet. Heat reduction in a fire is accomplished through the absorption of energy through steam conversion. Smaller droplet size equates to a greater surface to volume ratio which allows for increased surface contact with the fire resulting in more steam conversion.Water Droplet Size Comparsion
 Surface tension reduction allows the water to spread more rapidly resulting in increased wetted surface area and increased penetration.
Plain Water
 The diagram above illustrates that the high surface tension of the water (72 dynes/cm) limits its spreading ability, thus causing a bridging action over the pores which does not allow for penetration.
Wetting agent
 The diagram above illustrates how a wetting agent reduces water's surface tension, thus providing for greater surface coverage and penetration into the pores of the material.
Note: Wetting agents do not have the ability to form and maintain foam blankets or micelles.
Class A and B Foams
Foam Fire Suppression Mechanics rely on two main mechanisms:
1. Reduction of Surface Tension-
Like a wetting agent, foams reduce the surface tension of water.
This feature of foam aids in bubble formation and spreading of the foam blanket over the fuel surface.
2. Formation and Maintenance of a Blanket -
What differentiates foam from wetting agents is the ability to form and maintain bubbles (i.e., foam blanket) over the fuel.
The blanket insulates the fuel leg from the oxygen leg, mechanically depriving the fire of oxygen.
The blanketing properties of both Class A and B foams insulate the fuel relinquishing heat slowly.
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