Dry Powder Fire Extinguishers

How do powder fire extinguishers work?

Dry powder fire extinguishers remove oxygen from the fire by smothering the flames in a thin dust layer. They are filled with the active agent monoammonium phosphate and the fine particles spread easily across the fire when discharged, cutting off the fire from the surrounding oxygen in the air. This acts to supress the fire and ultimately extinguish it.      

Dry powder fire extinguishers are suitable for use on Class A, B and C fires. They are also safe for use on fires involving live electrical equipment.

• Class A (solid materials such as paper, wood, cardboard, plastics etc.)
• Class B (flammable liquids or liquefiable solids such as paint, oil, wax etc.)
• Class C (flammable gases such as natural gas, LPG etc.)

Where to use dry powder fire extinguishers

Powder fire extinguishers should be used outdoors, with the exception of boiler rooms, garages and some warehouses. Dry powder fire extinguishers are versatile and are recommended for use on garage forecourts, open workshops, goods yards and on vehicles. They are ideal for use outdoors as they will not be affected by freezing conditions like water-based extinguishers.

Using powder fire extinguishers indoors is not recommended as it could reduce visibility which may make it difficult to escape. When discharged indoors, the dry powder spreads quickly across a wide area. Dry powder fire extinguishers are non-toxic, however, there is a high risk of inhalation which can cause health problems such as respiratory issues and stomach irritation. Contact with the skin can cause redness and itching and contact with eyes can be harmful. Soft furnishings that come into contact with the powder are also very hard to clean.

Are dry powder fire extinguishers banned?

Powder fire extinguishers are not banned as they are not toxic, but they are mainly recommended for outdoor use, due to the possibility of reduced visibility and a risk of inhalation when used indoors.

ABC Powder Fire Extinguishers

An ‘ABC’ Powder Fire Extinguisher (or dry powder fire extinguisher), often referred to as general or multi-purpose, is designed to tackle Class A, B and C fires. This type of extinguisher typically use ammonium or a mono-ammonium phosphate mixed with other powders and works by smothering the fire, to starve it of oxygen. Dry powder extinguishers can be used in a number of locations but are most often found at petrol forecourts, in vehicles and garages, or where fire involving flammable liquids and gases could be a hazard. Whilst these extinguishers are versatile, being suitable for use on most common fire types, their use indoors is not encouraged due to the mess powder creates and the potential impairment of vision and effects on respiration it can cause.