There are a number of different extinguishing agents on the market, developed and designed to extinguish different types of fire. Fire are classified according to the combustible material involved.

Classes of Fire

Class A fires - are fires involving organic solids like paper, wood etc, as well as soft furnishings, fabric, textiles

Class B fires - are fires involving flammable liquids like petrol, oil or paints

Class C fires - are fires involving flammable gases

Class F fires - are fires involving cooking oil and deep fat fryers

Electrical equipment, like computers, does not fit in to any of the above classifications but has also been considered in this article.

It is essential to know which extinguishing agent should be used on which class of fire.

Types of Extinguishers

Water Extinguishers

are good for tackling fires involving burning paper, wood and soft furnishings, as the water soaks into the materials (Class A fires). This type of extinguisher does not leave a residue , but does have a comparatively low rating. Due to this factor water extinguishers are larger and heavier to overcome their lacking in fire fighting power. It is important to remember that water is a electrolyte and conducts electricity. Care must therefore be taken with regards to accidental use on mains power. These problems can, however be overcome by installing water extinguishers with additive. This type of   extinguisher has a higher fire rating, which therefore reduces the weight of the extinguisher and removes the risk of self-electrocution.

Foam Extinguishers

are suitable for flammable liquids and areas where soft furnishings and carpets are present (Class A and B fires). Foam extinguishers are safe to use with regards to electrical risk. This type of extinguisher usually contains additives which are carcinogenic, making the cleaning process of the premises after the vent of a fire more problematic.

CO2 (Carbon Dioxide) Extinguishers

contain only pressurised CO2 gas and leave no residue. This type of extinguisher is suitable for use on fires involving burning liquids (Class B fires), but is also an excellent solution for quenching fires involving computer equipment and other electrical appliances , as it does not cause damage to the electrical items and does not cause the system to short circuit. It is important to remember that when using CO2 extinguishers there is a possibility that once the gas has floated away the fire may reignite if the source of the fire is not removed (eg switching off the power supply). Please be aware that CO2 extinguishers that are not fitted with double-lined swivel horns may cause your fingers to freeze to the horn during the     deployment of the CO2 gas.

PowderExtinguishers,

also called ABC extinguishers, or dry powder extinguishers are suited to fight class A,B and C fires. Powder extinguishers have a good fire fighting capacity, but this agent does not soak into materials and does not  have a cooling effect on the fire. This could result in the fire reigniting, if it is not properly extinguished. Care must be taken when using powder extinguishers and they should not be used in small confined spaces where there is a risk of inhalation of the powder.

Wet Chemical fire extinguishers

are suitable for use with fires involving burning oil and deep fat fryers (Class F fires). These extinguishers come with a special application lance which lays a cooling layer of foam on top of the burning oil. Alternatively a fire blanket can be placed over the pan containing the burning oil. The pan should then be left to cool down. NEVER carry the pan outside or lift the fire blanket after a short period of time to inspect the burning oil as introducing oxygen through this action could reignite the fire. NEVER use pressurised water, powder or foam extinguisher on fires involving burning oils as the pressurised jet will cause the burning oil to be carried out of the pan onto surrounding surfaces causing more damage and a larger fire to tackle.

 

Regulations and Servicing of your Extinguishers

By law, employers must provide their staff with adequate means of tackling a fire in the workplace. There is also a legal obligation for a competent person to annually service the fire extinguishers to standard BS 5306 part 3. In addition, all fire extinguishers must  be maintained in working order and in good repair in between the services. This means that workplaces must also ensure that they carry out their own checks, at least monthly.

Monthly Visual Inspection:

Check for any sign of tampering. This may be missing or broken tamper tags or pins. Look for any signs of discharge. This may be water, powder or foam traces on the hose or horn of the extinguisher. Gauges showing low or high pressure (usually indicated by red). Any damage to fire extinguishers, rust, dents, missing parts etc. Workplaces with a high risk of damage to their fire extinguishers such as those kept on haulage vehicles should be particularly vigilant. Any damaged extinguishers must be replaced immediately or repaird by a servicing company

Competent Person

A ‘competent person’ is defined by the British Standard as: ‘a person with the necessary training and experience, with access to the relevant tools, equipment and information, manuals and knowledge of any special procedures recommended by the manufacturer of the portable fire extinguisher, to be capable of carrying out the relevant maintenance procedures of this standard’. We recommend using a BFC or BAFE registered company which employs qualified technicians, who undergo refresher training every 3 years to keep their industry knowledge up to date.

Annual Service

During a basic annual service, the fire extinguisher technician carries out various procedures on the fire extinguishers depending on their make and type. Generally, the service includes: Checking all fire extinguisher parts such as: valves, safety devices, gauges, and operating mechanisms. Checking that the pressure and weight is within the stated range. Issuing a ’Certificate of Inspection’ - a legal record of the maintenance carried out on the fire extinguishers to be kept by the customer and technician.

Extended Service (Discharge and Refill)

Extended service generally involves carrying out a test discharge on the fire extinguisher, checking internal and external parts, then recharging the fire extinguisher ready for use, if deemed safe by the engineer. BS 5306 - 3, states that water fire extinguishers, foam fire extinguishers, powder fire extinguishers and wet chemical fire extinguishers require an extended services every 5 years. Co2 fire extinguishers must have an overhaul & pressure test every 10 years. Most companys carry out a ‘service exchange’ for co2 and powder fire extinguishers due to be discharged. This entails exchanging your old extinguisher for a new or refurbished extinguisher. Buying new fire extinguishers from Budget-Fire may prove to be more cost effective than service-exchanging old units.

Fire Extinguisher Wall Signs

Each extinguisher must be accompanied by appropriate fire extinguisher wall signage. These signs indicate the type of extinguisher and give instructions about the use of the specific extinguishers.

Wall mounting

All fire extinguishers should, where possible, be wall mounted on a suitable bracket or placed on a fire extinguisher stand. All our extinguishers are supplied with the relevant wall bracket. Fire extinguishers should never be used to prop doors open - Especially fire doors which should remain shut unless an automatic fire door retainer has been fitted.  

Further information
This fire extinguisher guide is only a brief introduction. For further information please refer to: BS EN3 BS 5306 part 3 and 8, Regulatory Reform (Fire Safety) Order 2005

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