Fire Extinguishers
Your First Line of Defence
Water
Advantages: Water is usually inexpensive and readily available. It is an effective extinguishant for Class A fires.
Disadvantages: Water is only suitable for Class A fires. It may be dangerous on other classes of fires and must not be used on fires involving energized electrical equipment.


Foam
Advantages: Foam provides a lasting blanket to control the fire after the extinguisher discharge is complete. It can be used as a vapour-suppression barrier over flammable liquid spills.
Disadvantages: The extinguisher is an aqueous solution which requires to be cleaned up after use, particularly on painted surfaces, and must not be used on fires involving energized electrical equipment.
Wet Chemical
Advantages: This extinguisher provides rapid knockdown of fires involving cooking oils or fats and provides a lasting foam blanket to control the fire after the extinguisher discharge is complete.
Disadvantages: The solution is usually alkaline, and consequently will corrode some metals, especially aluminum. It may also irritate eyes and skin. Prompt clean up is advised. It must not be used on fires involving energized electrical equipment.


Dry Chemical
Advantages: Powder provides a rapid ‘knock-down’ for a range of fires types. When dry it may be cleaned up with a vacuum cleaner.
Disadvantages: On discharge, the extinguisher forms a dense cloud of powder which may temporarily restrict vision and may cause respiratory irritation. AB(E) powder, when it contacts very hot objects, can melt and form a film which may be difficult to remove. After initial ‘knock-down’, it gives no protection against re-ignition of flammable liquid fires. While B(E) powder is not effective on class A fires, AB(E) powder is not effective on fires involving cooking oils and fats.
Carbon Dioxide
Advantages: Carbon Dioxide leaves no residue, is safe for use on fires involving energized electrical equipment, and is effective on fires in locations such as semi-sealed enclosures, which cannot be readily penetrated by non-gaseous extinguishants. It is the preferred extinguishant for use for in electronic environments.
Disadvantages: Carbon Dioxide has very poor ‘knock-down’, short discharge range and is almost totally ineffective in the presence of significant air movements. Because it displaces oxygen, atmospheres containing enough carbon dioxide to extinguish a fire do not contain enough oxygen to support life and could kill by asphyxiation. The carbon dioxide fire extinguisher discharges forming a cloud of very cold gas and some solids (dry ice). It produces a loud noise during discharge that may startle inexperienced operators.
