Exercise 4. Read text F Types of Portable Fire Extinguishers

NFPA classifies fire extinguishers as follows:

Water-based Extinguishers include water, water spray, water mist, aqueous film-forming fluoroprotein foam (FFFF). Water extinguishers are suitable for Class A fires. Foam extinguishers are mostly effective on fires involving flammable liquids and gases.

Dry Chemical Extinguishers are usually rated for multi-purpose use. Multi-purpose dry chemical (ammonium phosphate) is mostly used on Class A fires. Ordinary dry chemical extinguishers employing sodium bicarbonate are not listed for Class A fires, effective on flammable liquids and gases, as well as electrical fires. Special dry chemical extinguishers employing sodium chloride, dry graphite or dry copper are effective on fires involving burning metals.

Wet Chemical Extinguishers are based on a solution of potassium acetate having the effect of turning cooking oil into a soap-like substance and that of smothering the fire. These extinguishers are effective on fires involving cooking oils, fats and greases.

Carbon Dioxide Extinguishers are listed for flammable liquids and gases fires. Moreover, these extinguishers are well suited for fires involving sensitive electrical equipment because carbon dioxide does not leave any residues after use.

Halon (Halogenated) Extinguishers contain a gas that inhibits a chemical chain reaction taking place when fuel burns. These types of extinguishers are often used to put out Classes A and B fires, as well as to protect valuable equipment since halon leaves no residues to clean up.