Dry Powder Fire Extinguisher

Dry Powder fire extinguishers are the most versatile portable fire-suppressant available on the market, and are suitable primarily for Class B or Class C fires (although only on small liquefied gas fires that belong to Class C). Dry powder can also be used on Class A fires if necessary but it is not the best type of extinguisher for that class. Specific dry powders are also available for certain situations, such as metal fires or for use in the motor industry. Dry powder is also a good choice for fires involving electricity, however if the fire involves computers or other delicate machinery, CO2 is a better choice as it does no damage to the equipment. Dry powder leaves a sticky and corrosive residue behind that could cause damage.

A dry powder fire extinguisher is identifiable from other types by the blue band on the upper half of the canister covering less than 5% of the total surface. The rest of the surface of the unit is bright signal red, the same as other types. A pressure gauge will be present towards the top of the unit, near the trigger and nozzle. There will always be a nozzle to direct the extinguishing agent, but larger models (usually any with a weight of 3kg or more) will come equipped with a hose to allow better control over the direction of the dry powder.

Dry Powder Fire ExtinguisherMost dry powder canisters come in three different sizes – 1kg, 2kg and 6kg, although 12kg is also available. The size of the canister is dependant on the fire risk in the area in which it is installed. Smaller models are ideal for the home and small offices or workshops, or even cars. This type of extinguisher is also suitable for storing in colder environments such as garages or outhouses, as they are capable of operating between the temperatures of -30°C and 60°C.

These types of extinguishers are filled with an inert chemical powder and pressurised by a gas (usually nitrogen). Different powders can be used, most commonly Monoammonium phosphate or Sodium bicarbonate. The powder works on release through a chemical reaction with the fire, which causes the particles to expand, inhibiting the combustion and eliminating the oxygen, causing the fire to die.

How to use a dry powder fire extinguisher

Using a dry powder fire extinguisher requires some skill as the technique is different to using some other types of extinguisher, and individuals should always be trained in using one if the extinguishers are present. For fires involving liquids in containers or spilled liquids, the nozzle needs to be directed at the near edge of the fire, and a rapid sweeping motion of the nozzle applied gradually towards the far edge. On fires involving flowing liquids, the nozzle should be directed at the base of the flames and swept upwards. If electricity is involved (or suspected), the main supply must also be shut off before any attempts to tackle the fire are made.

Dry powder extinguishers should never be used in confined spaces, as the chemical reaction caused by using it removes oxygen and has been known to do the same to the human lungs, which can cause asphyxiation. In extreme cases, this reaction can also cause cardiac arrest. Cases of death caused by usage of a dry powder fire extinguisher are very rare, however, and should not count against an otherwise excellent multi-purpose extinguishing agent.

Category: Fire Extinguisher Types