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How to choose a type of fire extinguisher

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Water, foam, powder, Co2 and Halon fire extinguishers

How to choose a type of fire extinguisher

What is a fire class?

A fire’s class tells you what fuel is being burnt.
• Class A: Ordinary combustibles (wood, paper, cloth, rubber, plastics)
• Class B: Flammable liquids (oil, petrol, gasoline, greases)
• Class C: Flammable gases (gas, propane, hydrogen)
• Class D: Combustible metals (magnesium, titanium, etc)
• Class E: Electrical fires
• Class F: Cooking fats, oils and electrical equipment

So, before buying an extinguisher, you should have a risk assessment carried out, to tell you what class of fire you’re most likely to encounter. You should then select an extinguisher that is safe to use on those types of fire.

If you’re confused, check the extinguisher’s label before buying; it will tell you what classes of fire it can fight.
More often than not, a combination of extinguishers will be needed to protect you from all potential risks.

Types of fire extinguisher

Water (H2O) fire extinguishers
• For class A fires
• The cheapest to buy and replace

Carbon dioxide fire extinguishers
• For class B fires
• The only suitable electrical fire extinguisher

AFFF foam fire extinguishers
• For class A and B fires
• Prevent fires from re-igniting by cooling them

ABC dry powder
• They fight Class A, B and C fires
• They’re the only recommended vehicle fire extinguisher

M28 and L2 powder fire extinguishers
• They’re the only suitable as metal (class D) fire extinguishers
• M28 powder cannot be used to fight lithium fires, L2 powder can

Water additive fire extinguishers
• For class A fire extinguishers
• With a water additive to make it’s knockdown rate higher

Wet chemical fire extinguishers
• For class F fire extinguishers
• The only suitable for kitchen and cooking fire extinguishers

BC powder extinguishers
• Suitable for class B and C fires

Monnex extinguishers
• Uses a potassium bicarbonate-urea based agent
• Developed for fighting class B and C liquid and gas fires

Protein foam fire extinguisher
• The most common type is FFFP
• For class A and B fires
• Creates a stronger foam layer than normal foam extinguishers

Alcohol-resistant (AR-AFFF) foam extinguishers
• For class A and B fires
• Foam layer is resistant to alcohol

The dangers of each extinguisher

You should also be aware of each extinguisher’s potential danger. Dry powder extinguishers, for instance, could obscure your vision and cause harm when inhaled.

Another example is the risk of thermal shock. M28 and L2 extinguishers are the only ones suitable to use on metal fires. Use another extinguisher and you risk getting a thermal shock. Although, some extinguishers have passed the 35kV conductivity of discharge test, which will reduce your risk if you accidentally use them on metal.

What is a fire rating?

A fire rating will tell you what size fire the extinguisher can fight. It appears as a number, followed by a letter. The number tells you the fire’s maximum size, and the letter indicates the fire’s class.

For instance, if a fire rating was 13A, you can use it on a 13sq ft., class A fire.

It’s important that you take this into consideration – water extinguishers and water additive extinguishers, of the same size, will both fight class A fires, but the water additive extinguisher will have a higher fire rating.

Wet chemical fire extinguishers are different; the number will tell you how many litres of oil it can be used on.

What combination of extinguishers?

If you need more than one type of extinguisher to protect your business, you should be aware of how they react with each other.

For instance, if you mix water and dry powder together, a corrosive matter will be formed, which will damage electrical appliances.

Also, some extinguishers will break down barriers formed by foam extinguishers.

Approvals

To make sure you are adequately protected, check that your extinguisher meets the standards laid out by one of the following governing bodies:

• British Standards approval (or BS EN)
• BAFE certification
• SIRA
• CE kitemarked
• MED (ships wheel) certified
• 35kV conductivity of discharge test
• Stichting Milieukeur Approval (Netherlands Environmental Certification)

Some of these are irrelevant, depending on your use. For instance, MED (ships wheel) certification is only necessary of your extinguisher is for marine use.
photo credit: estherase via photopin cc


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