Figuring out how best to put out a fire has been a debate through the ages and still, to this day, there is ongoing research which keeps improving fire extinguishers. In around 200 BC, there was a hand pump that was able to deliver water to a fire. The Romans used bucket chains, buckets passed hand-to-hand to deliver water to the fire. We’ve probably all seen that method in an old western movie where a farm house or barn is on fire. Not the most effective way to fight a fire but that’s all they had until the middle ages. It was then that ‘squirts’ were used. A squirt works like a bicycle tire pump except instead of air it sucked in about a litre of water. When the plunger was pushed it ejected water, in a stream, onto the fire.

The ‘squirt’ was one of the extinguishers used on the Great Fire of London in 1666. It wasn’t until 1819 that the first version of the modern portable fire extinguisher was invented.  These modern versions often used potassium carbonate or other substances that would interfere with the chemical reaction of the fire. These extinguishers were suitable for liquid fires, such as oil or gas, and for electrical fires. Electrical fires were fairly new at the time and it was discovered that fighting an electrical fire with a ‘squirt’ type extinguisher often caused the fire extinguisher handler to get electrocuted. Unfortunately, the vapour and combustion by-products were highly toxic and deaths did occur from using these extinguishers in confined spaces.

The late 19th century saw the invention of the soda-acid extinguisher, where a cylinder contained 1 or 2 gallons of water that had sodium bicarbonate mixed in it. Suspended in the cylinder was a vial containing concentrated sulphuric acid. The vial of acid was broken by one of two means depending on the type of extinguisher. Once the acid was mixed with the bicarbonate solution, carbon dioxide gas would be expelled, and this would in turn pressurize the water. The pressurized water was forced from the canister through a short length of hose and a nozzle. The acid was neutralised by the sodium bicarbonate.

In the middle of the 20th century we saw the modern type of extinguisher taking form. These extinguishers used different extinguishing agents and were all pressurized. It was clear that water was not always the best agent to extinguish a fire. If the fire is fuelled by a flammable liquid, such as oil or gas, water will simply disperse the flames and create more fires. Those types of fires are considered to be Class B fires and have always been difficult fires to put out. Foam or powder extinguishers were best used on this class of fires.

A fairly recent development is the water mist fire extinguisher, also called ‘dry water mist fire extinguisher’. All water mist extinguishers break up the water into fine mist particles which soak and cool the fire. The particles also evaporate just above the surface, rapidly expanding in size and thus starving the fire of oxygen. Many brands use de-ionised water, which cannot conduct electricity. This makes it a great extinguisher to have in your home or office as it is safe to put out many different classes of fires, including electrical fires. They are even safe to use on people and animals since there are no chemicals involved.

Whatever situation you find yourself in, ensure you know what extinguisher you should have on hand. You should even try one out to see what it feels like. Many extinguishers, once triggered, will only last between 30 to 60 seconds. Knowing this can help you decide whether to try to extinguish the fire yourself or evacuate and call for help. Being prepared in case of a fire is best defence.