Pros and Cons of Fire Extinguisher types

Pros and Cons of Fire Extinguisher types

Classes of fire

Fires are classified according to the materials that are burning. This classification system allows you to choose the right fire extinguisher.

Fire is broken down into Six Classes – A, B, C, D, E and F.

Types of extinguisher

·        Foam

·        ABC Powder

·        Carbon Dioxide (CO2)

·        Wet chemical

·        Powder

·       Monnex

Foam – Suitable for Class A and B Fires

Class A – combustible solids (paper, wood)
Class B – flammable liquids (petrol, diesel, spirits, paint)

Pros

Higher A rating than water, so more effective on combustible solids. For example, a 6lt Foam has the extinguishing capability of a 9lt Water.

Foam discharge is easier to clean up than powder.

Foam is not as conductive as water, so it won’t cause as much damage if sprayed on electrical equipment.

Cons

It can be susceptible to frost.

ABC Powder – Suitable for Class A, B, C and Electrical Fires

Class A – combustible solids (paper, wood)
Class B – flammable liquids (petrol, diesel, spirits, paint)
Class C – flammable gases (methane, butane

Pros

Ideal as a multipurpose extinguisher for home and work.

Twice as effective as Foam on Class A fires, for example: a 6kg Powder is rated 27A, whereas a 6lt Foam is rated 13A.

Not as susceptible to frost as water-based extinguishers.

Very effective for burning and free-flowing liquids.

When powder is applied to hot smouldering surfaces, the particles fuse together and swell. This forms a barrier which excludes oxygen and prevents reigniting.

Cons

Can be messy, as it’s a fine powder. Clean up can be costly and time-consuming, so consideration should be given where misuse/accidental use would be an issue.

Reduces visibility when discharged, so consideration required when placing near escape routes, stairwells, etc.

May aggravate respiratory conditions when discharged.

Limited cooling properties.

While Powder is safe for use on electrical fires, it can cause corrosion.

CO2 – Suitable for Class B and Electrical Fires

Class B – flammable liquids (petrol, diesel, spirits, paint)

Pros

Smothers fire quickly in draught-free conditions.

A non-conductor, so can be used on live electrical equipment.

Leaves no residue and is not as damaging to electrical equipment as powder.

Cons

It’s an asphyxiate, so care should be exercised when using in confined spaces.

Limited cooling properties and no protection against reigniting.

A non-insulated horn can cause frost burn if user accidentally touches the horn when in use.  Frost- free horns offer some protection against this (a frost free horn has a honeycomb ring on the internal lining; non-insulated horns have a single layer of plastic).

Wet Chemical – Suitable for Class F Fires

Class F – cooking oils and fats

Powder – Suitable for Class D Fires

Class D – metals
Specialist Class D Dry Powder for Flammable Metals.

Monnex – Suitable for Class B and C Fires

Class A – combustible solids (paper, wood)
Class B – flammable liquids (petrol, diesel, spirits, paint)

Pros

High performance specialist powder extinguisher.

Also safe to use on flammable chemicals.

Ideal for garages, fuel depots, airports, motor racing events and chemical stores.

Automatic Extinguisher

Dry powder extinguisher ideal for use on oil or gas burners. Heat activated. No manual intervention required.

Water Extinguishers

Water has excellent cooling properties but is only suitable for use on Class A fires. Foam is often the preferred option, as it is suitable for both Class A and B and has a better A rating.

Halon

Under the European Council Regulation 2037/2000, Halon portable fire extinguishers are no longer permitted for use in the European Union due to their ozone-depleting substances. Exceptions include use in civil aircraft, the armed forces and the emergency services.

Class F – cooking oils and fats

Fire rating system

Fire rating refers to a fire extinguisher’s fire-fighting capabilities.

Although fire is categorised into 5 classes, only classes A, B and F carry a fire rating.

You will find the rating printed on the body of the extinguisher – for example: 13A/75F.

In this example, the prefix numbers 13 and 75 refer to the size of the fire and the letters A and F represent the Class of Fire on which to use the extinguisher.

The higher the prefix number the greater the fire extinguisher’s fire-fighting capabilities.

In this instance, the extinguisher is suitable on a Size 13 Class A (Combustible Solids) fire and also on a Size 75 Class F (Cooking Oils & Fats) fire.

In Class A the size refers to 13 metres in length, while in classes B and F the 75 represents volume in litres.