Fire

Fire & its Causes

• The fire triangle

• The fire triangle is a simple model that illustrates three ingredients necessary to start most fires. In industry it has largely been replaced by the fire tetrahedron, which provides a more appropriate model due to some of the potential chemical reactions that may occur.

 • The triangle illustrates the three elements required to

start and maintain a fire, these are heat, fuel, and oxygen. A fire can be prevented or extinguished by removing any one of these elements.

Fire Triangle

OxygenFire Triangle

Ignition source

Fuel

FIRE

Types of Extinguisher

• The type of extinguisher is identified by a colour coding as indicated below. The old standard the extinguisher was painted entirely the colour of the appropriate colour code. You will find these in many premises and are legal, you do not need to change them unless the extinguisher is defective and need to be replaced. New extinguishers use the new standard.

• Water extinguishers are coloured signal red.

• Other extinguishers will be predominantly signal red with the manufacturers label, a band or circle covering at least 5% of the surface area of the extinguisher of a second colour to indicate the contents of the extinguisher. I prefer the band around the extinguisher if the new standard is used because it can be seen from any angle.

• The old standard, the entire body of the extinguisher was colour-coded.

Water Fire Extinguisher

Used on class A fire; wood, paper & textiles.

Question.

What elements of the fire triangle does the water extinguisher remove?

• Ignition source (heat)• Oxygen

Why is this type of extinguisher unsuitable for electrical fires?

Water Fire Extinguisher

• Water fire extinguishers do not generally contain strong chemicals and has a low fire fighting rating however, it’s proven safe for its use and the environment.

• Water-base fire extinguishers are usually used on burning organic materials such as papers and wood.

• This kind of fire extinguisher is recommended to be used in homes where common fire prone materials such as cloths, curtains, wood furniture are located.

• However, since water is an electrolyte, you cannot spray it on power cables and sockets as it might be more dangerous and may cause electrical grounds.

• Though some water-based extinguishers have additives that produces zero electrolytes, its fire fighting rating still remains the same and can only be used on such organic materials.

Carbon Dioxide Extinguisher

Used on class B fire; flammable liquid & electrical

Question.

What elements of the fire triangle does the water extinguisher remove?

• Ignition source (heat)• Oxygen

Why should you be careful using this type of extinguisher of flammable liquids?

Carbon Dioxide Extinguisher

• Known as the most recommended fire extinguisher for electrical and kitchen appliances, it’s because this type of fire extinguisher doesn’t leave any residue.

• What it does is overpower the amount of oxygen that keeps the fire alive through emitting carbon dioxide through high pressured nozzles. CO2 fire extinguishers are best for burning home and office appliances such as computers, ovens, sockets etc. because as it puts out the fire, it doesn’t damage the electrical systems nor does it  cause further short circuit. CO2 is also very cold when sprayed so it can cool down the temperature of the burning object.

• However, you must know how to handle and use it so as not to freeze your own fingers.

Foam Spray

Used on class A & B fires; wood, paper & textiles.

Question?

What elements of the fire triangle does the water extinguisher remove?

• Ignition source (heat)• Oxygen

Why is this type of extinguisher suitable for flammable liquids?

Foam Spray

• What foam fire extinguishers basically do is reduce the oxygen from the fire drastically as it smothers it with foam.

• These extinguishers still have a bit of water content and this reacts on content the burning material, it then turns into liquid however it is not as wet as the water-based kind.

• Foam is lighter than the oil and ‘floats’ on top of the burning liquid, this isolates the fuel from the oxygen as well as cooling the flames.

Dry Powder

Used on class A, B & C fires; wood, paper & textiles.

Question?What elements of the fire triangle does the water extinguisher remove?

• Oxygen

Dry Powder

• Also known as ABC powder extinguishers, this has a high fire fighting rating and can basically put out fires within in degrees of A, B and C.

• The only disadvantage is that the powder doesn’t penetrate deep enough on burning objects and it cannot cool down high temperatures.

• Because of this, one must ensure that the fire is completely gone before stopping the process of extinguishing or else there might be another re-ignition

• Fires have been classified into four groups A, B, C, and D

• Class A fires – are fires involving organic solids like paper, wood, etc

• Class B fires – are fires involving flammable Liquids.

• Class C fires – are fires involving flammable Gasses

• Class D fires – are fires involving Metals.

• Class F fires – are fires involving chip pan.

• What should you do if you discover a fire? – You must get everyone out as quickly as possible and call the fire brigade.

• However you may discover a fire in its very early stages and think that you can deal with it yourself.

• The first thing that you should remember is that fire spreads very quickly.

• Even a small contained fire can quickly spread, producing smoke and fumes which can kill in seconds. If you are in any doubt do not tackle the fire, no matter how small.

• You can put yourself at risk by fighting the fire.

• If in doubt get out, get the brigade out, stay out.

Ignition Source

Fuel

Oxygen