Powder fire extinguishers are some of the most versatile fire control options. They work not only for class A and class B fires (normal fires and flammable liquids), but also on class C fires, which involves gases like butane and propane. They’re also safe to use on electrical fires because the dry powder contained in these extinguishers is non conductive. Powder expelled from these extinguishers work to knock down flames. Flammable liquids and gases are particularly susceptible to being put out by this method.
These fire extinguishers come in a number of types, but they are all filled with powder and pressurized using nitrogen. The jet can travel four to seven metres, and a full discharge takes between six and twenty seconds. How long your fire extinguisher will take to discharge and how far the jet will go depends on the exact type of extinguisher you’re using. Some have control devices and controlled discharge, which help with maintenance. Here are a few of the types of powder fire extinguishers you might encounter.
BC extinguishers are rated for liquids and gases, but not for other types of fires. These are filled with potassium bicarbonate or sodium bicarbonate, and leave a sediment behind. This material should be cleaned off immediately, as it’s mildly corrosive, and can damage materials that it’s in contact with for long periods. ABC dry powder fire extinguishers work on class A fires as well, and are filled with monoammonium phosphate. This yellow powder also leaves a residue, and can damage electrical equipment. Avoid using it around this kind of equipment.
It’s important to read the instructions on a fire extinguisher and familiarize yourself with its use. Don’t allow it to sit until you have a fire. To use a powder fire extinguisher, pull the pin, aim the extinguisher, and squeeze the trigger. Be sure that the jet of powder is aimed at the base of the flames, then sweep it from side to side, covering the fire. If the fire is in a container, or is burning spilled liquid, aim the powder jet at the near side of the fire, then use it to propel the fire away from you until it goes out.
Flowing liquid which is on fire should be treated differently. Aim the jet at the base of the flames, then move it upward. If you need to use a powder fire extinguisher on an electrical fire, and there are no other options, turn the current off first. Once the fire looks like it has gone out, wait a while to make sure the air is clear, and investigate the site of the burning. Some fires may reignite, so be ready to discharge the extinguisher again.
Powder fire extinguishers should be located in an obvious and easy to get to position. They can be identified by the blue band or label on the outside of the red extinguisher. Older powder fire extinguishers may be entirely blue. If you have one of these, it’s important to make certain that it’s still in working condition. Make sure you maintain yours once a month, and have them serviced yearly. After a number of years, have a powder fire extinguisher pressure tested to be sure that the cylinder remains safe. When you buy new extinguishers, look for the kitemark of approval, which says that the extinguisher has been tested. All sizes of extinguishers, from tiny 1 kg models to large, wheeled, 100 kg models, should be kitemarked.
Keep powder fire extinguishers around the home or workplace in any location where a fire may start. Since these extinguishers work well on liquids and gases, they may be stored by stoves and furnaces, in garages, or in any other place where a non-electrical fire is a hazard. Be careful when using them, and always learn how to operate an extinguisher in advance of an emergency. Remember that you’re not obligated to fight a fire. If you’re unsure of what to do, or the extinguisher runs out before the fire is out, be willing to leave. Never allow the fire to get between you and an exit, and don’t stand in a location where smoke or fumes might be a danger.