Anyone who is likely to have to use fire fighting equipment should be trained in its use and in basic fire-fighting techniques. It is also essential that the right type of extinguisher is used for the fire.
Choosing the wrong type of extinguisher can have life-threatening consequences. Using a water extinguisher where electricity is present could result in electrocution. Some water spray and water mist extinguishers are approved for use on electrical equipment. Approved extinguishers will be marked on the body of the extinguisher as “Approved to 35 kV dielectric test”. This means that they have been tested to 35,000 Volts at one meter. Water spray and water mist extinguishers do not conduct electricity through the spray or mist because, unlike a water jet extinguisher, there is no continuous path.
Carbon Dioxide (CO2) and dry powder extinguishers prevent oxygen reaching the fire and extinguish it but they do not cool the burning material as water does, so if the powder gets blown away the fire can reignite.
Foam extinguishers are primarily designed for use on Class B fires, they are also effective on Class A fires because they are predominantly water-based. Foam spray extinguishers often also carry dielectric test approval.
Using a fire extinguisher
Fire extinguishers should not be used by people who have not been trained. Before tackling a fire with a fire extinguisher make sure you or someone else has sounded the fire alarm and that you have a safe evacuation route.
Using the correct type of extinguisher for the fire, use the four-step PASS technique.
- Pull: Pull the pin, this will break the tamper seal.
- Aim: Aim low, pointing the nozzle or hose at the base of the fire. Do not touch the horn on a CO2 extinguisher, it gets very cold and can damage the skin.
- Squeeze: Squeeze the handle to release the extinguishing agent.
- Sweep: Sweep from side to side at the base of the fire, the fuel source, until the fire is out.
If there is the slightest doubt or uncertainty about tackling the fire evacuate the building immediately.
Marsden Fire Safety offers a range of training courses including practical fire extinguisher training.