SOLID AEROSOL TECHNOLOGY

What is a solid aerosol agent?

• A family of the fire extinguishing chemicals normally in a solid phase
• Upon actuation, a chemical reaction occurs which generates a gaseous product that condenses to a fine particulate
• The particle size is approximately 1 - 5 microns. It is:
  - Bigger than that of air, nitrogen, or carbon dioxide.
  - Smaller than that of the dry chemicals.
  - It is classified as an aerosol.
  

How is the aerosol generated?

• The agent is a mixture of chemicals, including oxidizer and filler.
  - The oxidizers are usually potassium based.
  - The agent can be made in solid of powder forms.
  
• To activate the chemical reaction requires a spark or heat.
• The chemical reaction takes place in a ''generator'', a mechanical housing, which can be mounted in the hazard area.
• Reaction products:
  - 40% solid particle: (˜1 micrometer dia.) K2O, K2CO3, KCL, and other salts.
  - 60% gases: N2, CO2, H2O, and traces (PPM) of hydrocarbons.
• The residue does not generate HF or other acids as do some halon alternative candidates. The residue is water-soluble.

Fire extinguishing mechanism

• Breaking the combustion chain
  The fire suppression mechanism of solid aerosols is still under investigation. It is commonly accepted that the aerosol breaks the combustion reaction chain. The hydrogen (H) and oxygen (O), hydroxyls (OH) and other radicals are considered to be the fire chain carriers during flame propagation. The aerosol particles create a large surface area for capturing these radicals. As a result, the fire reaction chain is broken and the fire is extinguished. Fire experiments show that for dry chemicals, the smaller the particle size, the higher the extinguishment efficiency. This is also true for solid aerosols: the smaller particle size provides for better dispersion and a more effective aerosol.
• Cooling
  The aerosol by-products, CO2 and water vapor act as coolants and inertants in the fire, and also help to extinguish the fire.
• The aerosol is efficient on extinguishing both Class B and Class A fires, as well as electrical generated fires up to 24.000V.

Fire extinguishing effectiveness

Because of the high expansion and small particle size, the solid aerosol achieves substantially higher extinguishing power. The following table compares solid aerosol with other agents. To protect the same volume, solid aerosols requires less weight and lower storage volume.

Toxicology, corrosivity and transportation

• The following data is from the US Naval Research Laboratory. The averaged final gas concentrations from a 50 gr/m3 design solid aerosol concentration are:
  
  O2 : 20.3% N2 : 76.9% CO2 : 1.37%
  CO : 0.3%    Ar : 0.87%

Therefor, the resulting gases and solids are not toxic.

• Suitable for exposure to Monel 400, stainless, nickel, brass, zinc and
  Copper, can be corrosive to steel, aluminum, and magnesium in the presence of moisture. However, the extremely fine residue (water-soluble) from the solid aerosol is easily removed by vacuuming, blowing with air, wiping with a cloth, or (where practical) water spray. Therefor, the potential for corrosion can be eliminated by removing the residue.
• EPA's SNAP program has listed solid aerosol as an acceptable total flooding agent as a halon alternative used in non-occupied situations.
• Third party testing to DOT standards found that the aerosol generators can be shipped without regulation