Fire-Extinguishing Systems

So, the elimination of oxygen can extinguish the fire. Unfortunately, that has inherent drawbacks, such as the fact that without oxygen, people cannot breathe. That's why firemen wear oxygen tanks into a fire. They need it to breathe while doing their job of rescuing people trapped in an inflamed structure. But removal or reduction of that oxygen will also limit the fire. That is why, when a fire is detected by an air handling system, fire dampers close and the units are de-energized. This reduces the amount of outside air introduced into the fire. Obviously, if a structure is burning, removing the fuel is just not going to happen. Heat is an element which can be removed or reduced, so plenty of systems to fight fire deal with removing or reducing the heat generated.

The term fire-extinguishing systems describes various kinds of fire extinguishing methods. Each is described in detail in its respective section. Carbon-dioxide fire-extinguishing systems work by eliminating oxygen. The video above shows a Safety First System test discharge. Upon detecting a fire, the system automatically shoots out carbon dioxide to deplete the fire of oxygen, thereby putting it out. The carbon dioxide immediately disperses, leaving no mess behind.

The second method is called a clean-agent fire-extinguishing system. This system is more effective than carbon-dioxide systems, and covers a larger area. Clean agent fire-extinguishing systems extinguish the fire but allow humans to breathe while they escape the hazard. The following video shows a number of remarkable tests using this kind of system. AF11E is a clean-agent fire-extinguishing medium that is gaseous, volatile, and is electrically non-conductive, and leaves no residue after evaporation. Carbon dioxide (CO2), Halons, and Hartindo AF11E are classified under this type of system. However, Halons have been banned (under the Montreal Protocol of 1989 of which Malaysia is a signatory), and high indoor air concentrations of CO2 can be hazardous to the human body. Furthermore, increased levels of CO2 in the atmosphere may be implicated in global warming.

Another method is a wet-chemical fire-extinguishing system. With a wet-chemical based fire-extinguishing system, after the fire is extinguished, the property owner must deal with the chemical residue left behind. The following video shows a foam chemical extinguishing a gasoline fire.

The other type of fire-extinguishing system included in this section is a dry-chemical fire-extinguishing system. Dry-chemical extinguishing systems are useful for fires extinguished by either sodium or potassium bicarbonate, class ABC fires, or ammonium phosphate, class BC fires. Dry-chemical extinguishing is the best all-around choice for common fire situations. They have an advantage over CO2 and clean-agent extinguishing in that they leave a blanket of non-flammable material on the extinguished material, reducing the likelihood of re-ignition. Dry chemical extinguishing systems make a lot of mess, but if the choice is between a fire or a mess, then it would be wise to choose the mess.

As with any fire-extinguishing system, follow the local fire marshal’s recommendations for maintenance and testing.  Also follow OSHA and any other authorities having jurisdiction. There should be a regular testing schedule for all life safety devices. Replacement would occur if the device ever failed a test or if the code changed, requiring a different type of fire-extinguishing system.  The following are a few of the manufacturers of fire-extinguishing systems.

• Carbon-dioxide fire-extinguishing system products may be manufactured by Ansul, Chemetron Fire Systems, Kidde Fire Systems, SimplexGrinnell or other equal systems.
• Clean-agent fire-extinguishing system products may be manufactured by DuPont Fluoroproducts, Kidde Fire Systems, SimplexGrinnell, Minimax, Chemetron Fire Systems or other equal systems.
• Wet-chemical fire-extinguishing system products may be manufactured by Ansul and Badger or other equal systems
• Dry-chemical fIre-extinguishing system products may be manufactured by ADX Fire Protection Inc., Amerex Corp, Ansul Inc., Vipond Inc, Wheatland Tube Co. or other equal systems.