Advice for tackling office based fires

Although water has been used to tackle fires for thousands of years, the type of fires which water-based fire extinguishers can defeat are somewhat limited, especially in an office environment.

Electrical appliances are a chief source of office-based fires. After all, most offices these days are full of computers, printers, monitors, scanners and photocopiers so this really should come as no surprise. Of course, using a water-based extinguisher has some major drawbacks in this type of environment.

Firstly, it is not always possible to turn off the power supply when a serious incident happens very quickly. So, even though water may well suppress or even extinguish an electrical fire, it will also conduct electricity, thereby putting your life at great risk. Indeed, the jet of water between the extinguisher in your hands and the target fire will connect you to the electricity and create a circuit that will result in you being electrocuted. However, there is a solution available. Water extinguishers with additives or even dry water mist extinguishers are safe to use near electrical items.

Secondly; even if you did have the presence of mind to switch off the power before tackling the fire with water, you will most likely cause further damage to the circuitry and electronics of other expensive equipment which may not directly be involved in the fire. Of course the same limitation applies to foam extinguishers and powder fire extinguishers.

Whilst water fire extinguishers are a very clean option and additives etc are available for them it is important to know their limitations to ensure both you and your work colleagues always remain safe.

In general we would for the above reasons recommend powder extinguisher, CO2 fire extinguishers and dry water mist extinguishersin offices. These types of fire extinguishers do not conduct electricity and will limit the damage that could be caused to office equipment.

Browse our pages further to learn more about occupational fire safety and fire extinguishers.

Introduction to foam fire extinguishers

When foam fire extinguishers first came into being, it was fair to say that they weren’t a massive success. Indeed, these early variants produced foam which was thick, gloopy and, because of the high animal protein content, smelled absolutely terrible. Thankfully, today’s Aqueous Film Forming Foam (AFFF) extinguishers are a distinct improvement.

AFFF extinguishers are painted red with a cream panel and are widely considered to be one of the best all-round units available. AFFF foam extinguishes and smothers flames when it is initially sprayed onto a fire. After this, it seals in combustible vapours under the film of foam and penetrates any absorbent materials, cooling the fire as the water in the foam evaporates. The spray nozzle on foam extinguishers allows a fire to be coated quickly and evenly. Furthermore, some foam extinguishers have been dielectrically tested to 35,000 Volt and are safe near live electrical equipment.

Foam is particularly effective on Class A fires (those involving paper, wood, etc) so they are a very good choice for offices or similar environments which contain a lot of fabrics. When used on flammable liquid fires (Class B), AFFF foam forms a film that prevents re-ignition of the flammable liquids by sealing the liquids off from oxygen. Class B fires also include man-made fibres which might liquefy in the heat of a fire.