Types of Fire Extinguisher
There are several different types of fire extinguisher available, and it can often cause confusion on which ones are required. Below is a quick reference guide to the most common types of fire extinguisher likely to be required and the types of fires that they can be used on.
Water Fire Extinguishers
Water fire extinguishers are one of the most common types of extinguishers found, they work by cooling the fire which then extinguishes it.
Classes of fire
- Class A – Flammable Solids.
Pros
- Clean with no adverse environmental impact.
- Cheap and easy to refill.
Cons
- Will freeze if left outdoors in cold weather unless a low freeze additive has been used. As an example, water fire extinguishers would not be a good choice for use on a construction site or petrol forecourt as during the winter months it is possible that they will freeze and not be able to be used.
Foam Fire Extinguishers
Foam fire extinguishers are similar to water but include a foam concentrate which is added to the water. When discharged the extinguisher produces a foam solution that can be used to smother fires.
Classes of fire
- Class A – Flammable Solids.
- Class B – Flammable Liquids.
Pros
- Can be used on both Class A and B fires making it versatile.
Cons
- Will freeze if left outdoors in cold weather unless a low freeze additive has been used.
- Most foams are not environmentally friendly.
Carbon Dioxide Fire Extinguishers
CO2 fire extinguishers are one of the most common types of fire extinguisher found and are normally provided to provide protection for electrical equipment which may catch fire. They work by displacing the oxygen around a fire removing one of the essential components of the fire triangle.
Classes of fire
- Class B – Flammable Liquids.
- Electrical – Whilst there is no specific class for electrical fires, CO2 extinguishers are commonly provided and used on this type of fire.
Pros
- Clean.
- Can be used on fires involving electrical equipment.
- Non-conductive and non-corrosive when used on electrical equipment.
- Can also be used on small Class B fires making it a dual-purpose fire extinguisher.
Cons
- Can be loud when discharged.
- Parts of the extinguisher can become very cold when discharged posing the risk of cold burns to the hands if touched. CO2 fire extinguishers sold with “frost free” discharge horns reduce this risk.
- May be unsuitable for use outdoors where wind may disperse the CO2 away from a fire.
- Should be used with caution in confined areas.
Powder Fire Extinguishers
Powder fire extinguishers are versatile as they can be used on multiple different types of fires. They work by smothering the fire with powder.
Classes of fire
- Class A – Flammable Solids.
- Class B – Flammable Liquids.
- Class C – Flammable Gasses.
- Fires involving electrical equipment.
Pros
- Can be used on Class A, B, C and fires involving electrical equipment.
- Will not freeze in cold weather.
- Powder fire extinguishers often have the highest firefighting ratings.
- Can be used on running fuel fires.
Cons
- Very messy when discharged.
- Potential to contaminate equipment or food.
- Should not be specified for use indoors unless justified by a health and safety risk assessment as they can cause respiratory distress.
Class D Fire Extinguishers
Class D fire extinguishers are a specialist type of fire extinguisher and are not commonly found.
Classes of fire
- Class D – Flammable Metals
Pros
- Able to put out fires involving flammable metals.
- Easy to refill
Cons
- Expensive when compared to the more common types of extinguisher.
Wet Chemical Fire Extinguishers
Wet Chemical fire extinguishers are intended primarily to fight fires involving cooking oil. They work by the process of saponification where the cooking oil is turned into a substance that will not burn. They will commonly be found in places like fish and chip shops and commercial kitchens where deep fat frying takes place. Cooking oil fires can be dangerous and if the wrong extinguisher is used serious injuries can occur and the fire is likely to become much worse. If you have a premises where deep fat frying takes place it is vitally important that you have the correct fire extinguisher to provide cover for this fire risk.
Classes of fire
- Class A – Flammable Solids.
- Class F – Cooking Oil.
Pros
- Safe to use on cooking oil fires.
- Dual purpose – can also be used on class A fires.
Cons
- More expensive when compared to the more common types of fire extinguisher.