Aerosol Fire Extinguishing Technology

The search of new fire fighting technologies has demanded to use the existing fundamental discoveries and developments in the sphere of volume fire fighting.

The most effective volume fire extinguishing agents are the oxides of alkaline metals in the substance of fine solid aerosols, which have extensive surface and being produced during the burning of solid fuels and pyrotechnical compounds. These compounds can burn independently without air access. The substance has a very high extinguishing ability for the hydrocarbon flames excelling the extinguishing gases.

The volume aerosol fire extinguishing system is based on the inhibiting chain reactions in the zone of burning flame by fine solid particles which are produced as a result of burning the aerosol producing compound cartridge. These particles can stay active during 30-40 minutes.

When the extinguishing concentration of aerosol is achieved in the room, the flaming combustion stops, the heat in the burning spot decreases and the temperature of the gas environment in the room drops. The fire extinguishing concentration of aerosol persists during 10-15 minutes after completion of generator operation. This makes the repeated ignition impossible.

The aerosol producing compound can be formed in the solid cartridges of different shape. Production of aerosol generators is based on these aerosol producing cartridges.

Aerosol fire extinguishing systems are used for liquidation of fires in different premises and objects. The use and limits are determined by the standards, rules and other official documents of local emergency authorities.

Aerosol fire fighting systems can provide the fire safety in such conditions when traditional fire fighting technologies are not acceptable: on the transport, in electric rooms and tunnels, in unheated premises which have wide temperature range, in explosive environments, in conditions with lack of water.

The list of buildings and premises which are to be protected with automatic aerosol fire extinguishing systems is given in Russian Firefighting Standard. *

In current conditions of legislative control of fire safety, estimation of fire risks and stimulation of fire insurance, the owners of the buildings and premises are interested in the choice of effective, reliable and economic fire extinguishing systems.

The most demanded are solid aerosol forming compositions, the extinguishing ability of which exceeds all fire fighting methods which are used for volume fire extinguishing. This is demonstrated in the table given below.

The analysis of the technical and economical characteristics shows that most of substances which are traditionally used for volume fire fighting, have lower extinguishing ability than the aerosol, and fire extinguishing systems which use such substances are bulky, difficult in operation and expensive.

Aerosol fire extinguishing is profitable. The price for all components is lower, and besides the aerosol fire extinguishing does not require additional operational costs. For example, the gaseous fire extinguishing system which has been installed in the cable spaces of Lefortovo road tunnel, costs 5.3 times more than the aerosol system of the same capacity.

Halocarbons which contain chlorine and bromine, are destructive for the ozone layer. Their production and application are suspended. During aerosol generator operation the contents of oxygen in the atmosphere is practically not reduced. The fire extinguishing aerosol is non-toxic, which allows to save human lives without harm to their health. Besides that aerosol does not have any negative effect to the equipment and other property.

Since aerosol forming compound which is used in generators is solid during storage and maintenance, generators do not require recharge and are always ready for operation. Generators of fire extinguishing aerosol provide fire safety in conditions when other methods cannot be used (water-scarce areas, unheated premises, transport, live high-voltage electrical equipment, etc.)

Aerosol fire extinguishing has significant advantage over other fire fighting methods: it's ecologically safe, non-toxic, which minimize the hazard to human's health. The residuals of aerosol can be easily cleaned by vacuum cleaner.

The use of aerosol fire extinguishing systems allow the owners to effectively protect their property from fire while making significant savings.

Characteristics of fire extinguishing methods

Halocarbon

Nitrogen N2

CO2

Powder

AFC

Extinguishing concentration (for organic inflammable materials), kg/m3

0,22-0,37

0,6-0,8

0,6-0,7

0,5-0,7

0,04-0,06

Operating temperature, ± ◦С

-35...+50

-50...+50

-35...+50

-50...+50

+-60

Volume of hermetic space protected by 1 kg of extinguishing compound, m3

2,7-4,5

1,25-1,7

1,4-1,7

1,4-2,0

17-25

*Table A of rules SP5.V130.2009 "Fire protection systems. Automatic fire alarm and fire fighting systems. Norm and rules of design."