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Fire is a chemical, exothermic reaction

Exothermic means it will produce heat

For fire to exist it requires

• oxygen
• heat , a source of ignition
• fuel
• and the chemical reaction of fire

These are put together to form the fire triangle (see diagram above).

To put out a fire you have to remove at least one of these items from the equation.

And that is the goal of a fire extinguisher.

This depends on the classification of the type of fuel that is burning.

	Class A - Trash, Wood, Paper
	Class B -Liquids, Grease
	Class C - Electrical equipment

Fire extinguishers will display on their casing what class of fire that they can be safely used on.

Water extinguishers

A water filled extinguisher can be used on a class A fire only. That's trash, wood and paper. Never use this kind of extinguisher on a flammable liquid that is already on fire, or near spilt or open containers of flammable liquid. Water will spread the flammable liquid and make the fire larger. Also never use on electrical equipment that is still connected to the power. If the item and surround areas can be safely disconnected from the power supply then and only then can water can be used.

Carbon Dioxide extinguishers

These extinguishers are filled with highly pressurized carbon dioxide (CO2). Commercially CO2 can be used as a refrigerant, made to put bubbles in soft drinks and "Dry Ice" which is solid CO2. CO2 is a non-flammable gas and does not conduct electricity. As the CO2 is released by the extinguisher the pressure that it was under dramatically drops causing the temperature of the liquid/gas to dramatically drop to almost -80 deg. C. Because of this ice may form at, and fly from, the horn. So this extinguisher displaces the oxygen and cools the fuel as well. Suitable for class B and C fires only and may be ineffective at extinguishing Class A fires because it may not be able to displace enough oxygen to successfully put the fire out. Class A materials may also smolder and re-ignite. Not recommended for use on a person who is on fire. Can cause frost bite, chemical burns and also death if inhaled.

Dry Chemical extinguishers

The one we recommend is rated for class A,B,C. (be aware that some are only rated for class B and C fires). The extinguisher shown to the right is a dry chemical type suitable for class A,B and C as you can see shown by the universal blue and white labels. The extinguisher sends out a fine dust/powder to coat the fuel creating a barrier to the oxygen. The powder also works to interrupt the chemical reaction of the fire. Hence the reason why you should aim at the base of the fire where the fuel is, failing to do so will mean it will be totally ineffective. There is also an optimal distance from the nozzle to the fuel for best coverage. Stand too close to the fire and you could waste the powder and run out before covering all the burning fuel. Stand too far away and the powder film will be too thin to be effective. Some of these extinguishers can be used on a person on fire (see extinguisher to right Filled with foray ®) without to much added inhalation risk. To be certain always check the MSDS for your fire extinguisher to find if there is any inhalation hazards.

 

Only fight a fire if it will not endanger yourself or others.

Fire extinguishers are only suitable for small fires no bigger than a car tyre

Do not fight the fire

• If the fire is quickly spreading beyond where it started
• If you can not fight the fire with your back to an escape route
• If the fire can block your only escape
• If you do not have the proper fire extinguisher
• You know that your fire extinguisher is too small for the job
• If you do not know what is burning
• If there are possible toxic fumes, excessive smoke (large synthetic materials such as the nylon in carpeting or foam padding in a sofa burn, they can produce highly toxic gases that can be fatal in very small amounts.
• If there is a possibility of an explosion
• or you do not feel comfortable with fighting the fire

If a person is on fire

• Inform them if they do not appear to know about the fire
• If they can not quickly brush the flame out themselves then,
• Instruct them to stop, drop to the ground, roll.
• Tell them to stop rolling once a smooth filament fire blanket is ready to smother any of the remaining flames

  • The best way to deal with a human torch fire (when clothing catches on fire), as confirmed by fire safety authorities, is to use an approved smooth filament fire blanket

• Cover the person with the fire blanket.
• If a class ABC dry chemical fire extinguisher is used. Get the person to cover the face (eyes, mouth and nose) with their own hands, if they have not already done so, before spraying at the head. Check the MSDS for your fire extinguisher to find if there is any inhalation hazard.
  • Following contact of soft tissue with the multipurpose dry chemical, the tissue exhibits a remarkable ability to resist infection and a normal capacity to heal following injury . This negligible toxicity of the multipurpose dry chemicals makes them safe for extinguishing the flaming clothes of human burn victims.
    reference: PMID: 459189 [PubMed]
  • For some dry chemical extinguishers when Inhalation occurs they can be treated as if a mineral dust was inhaled. Resulting with irritation to the respiratory tract. Transient cough, shortness of breath. Please check the MSDS of your extinguisher.
    reference: https://www.ansul.com
    
• If a Carbon Dioxide extinguisher is only option and is used, do not spray in the face where it could be inhaled. Avoid non-burning skin if possible.
  • Carbon dioxide can cause frost bite to occur on exposed body parts. Avoid the "snow" that comes out of the nozzel.
  • Carbon dioxide vapor is heavier than air and can cause suffocation by reducing oxygen available for breathing. Breathing high concentrations of vapor can cause lightheadedness, giddiness, shortness of breath, muscular tremors, and weakness. Also unconsciousness or even death!
  • Remore victim to fresh air. If cough or other respiratory symptoms occur, consult medical personnel. If not breathing, give artificial respiration. If breathing is difficult, give oxygen.
• Provide first aid to the burn victim.

If the ground or surrounding area is on fire.

• Follow the instruction for your fire extinguisher. Found printed on the side.

Do not fight the fire

• If the fire is quickly spreading beyond where it started
• If you can not fight the fire with your back to an escape route
• If the fire can block your only escape
• If you do not have the proper fire extinguisher
• You know that your fire extinguisher is too small for the job
• If you do not know what is burning
• If there are possible toxic fumes, excessive smoke (large synthetic materials such as the nylon in carpeting or foam padding in a sofa burn, they can produce highly toxic gases that can be fatal in very small amounts.
• If there is a possibility of an explosion
• or you do not feel comfortable with fighting the fire

Your pre light up safety check will include checking all your fire extinguishers.

• Are they ready to work?
• Is it free from any debris with pin intact?
• Check pressure guage is displaying full and expiry date is good
• Check it has no dents or corrosion
• Are they readily access able?
• What class fires can they be used on?
• Are their classifications suitable for your situation?
• Has your safety crew read their instructions and know how to operate if required?
• In what order are the methods that you use to put out a fire?
• At what point does the extinguisher get used?
• Who is in charge of their use?
• At what stage is a fire extinguisher not enough?
• Do you still have a safe escape route from the fire?
• Where is your fuel storage container?
• Is there any material in the local area that once on fire could produce dangerous toxic gases?
• Is there any material in the local area that once on fire could explode?
• Phone location and what number to ring for emergency services?
• Do you have clear instructions to direct emergency fire services (Fire Dept) to your location?

All fire extinguishers will have simple instructions lcearly printed on the side of the canister.

• Here is an example of what one looks like.
  But be sure to check the specific instructions found on the extinguisher that you are going to use.

References: Extinguisher Dry Chemical, Ansul Dry chemical MSDS, Carbon Dioxide MSDS, 

First aid for burns, Clothing and costume fire safety, Fire safety test,