Dry powder extinguishers tackle a wide range of fires and work in freezing temperatures. But the powder cloud makes them a poor choice for most indoor spaces.

Types of Powder

  • ABC powder – the most common type. Covers Class A (solids), Class B (flammable liquids) and Class C (gases), and doesn't conduct electricity.
  • BC powder – usually sodium bicarbonate. Covers Class B (flammable liquids) and Class C (gases), and doesn't conduct electricity, but isn't suitable for solids such as wood and paper.
  • Monnex – a high-performance powder based on potassium bicarbonate, for flammable liquids and gases. It achieves much higher Class B ratings than standard powders, so it's often used on high-risk fuel and chemical sites.
  • Specialist Class D powders – for burning metals such as magnesium, aluminium swarf and sodium. They're applied gently through a long lance so the burning metal isn't scattered. Different powders suit different metals – for example, L2 powder is designed for lithium metal, while M28 suits most other metals but not lithium.

Class D powders are not for lithium-ion batteries, which aren't Class D. See Lithium-Ion Battery Fires: What You Need to Know.

Why Powder Isn't Ideal Indoors

  • The powder cloud can make it hard to see your way out.
  • Breathing it in can cause coughing and difficulty breathing.
  • It gets everywhere and is hard to clean up. Damp powder can corrode metal and electronics, so sweep or brush it up promptly. Don't use a household vacuum cleaner – the fine powder will ruin it.
  • It doesn't cool the fire, so solids can reignite.

Older British Standard guidance said powder should generally not be used indoors. The 2023 edition (BS 5306-8:2023) removed that line, and instead asks you to weigh up the pros and cons of each type through your fire risk assessment. In practice, a water-based extinguisher plus a carbon dioxide (CO2) for electrical equipment is usually the better choice inside buildings. See Which Fire Extinguisher Do I Need?.

Good to know: if you travel abroad, you may notice that much of the world uses powder extinguishers everywhere, including indoors. In the UK, we recommend following the guidance in BS 5306-3 (servicing) and BS 5306-8 (choosing and positioning extinguishers), as many UK regulations and official guides follow the same advice.

Where Powder Works Well

  • Outdoor and unheated sites, where water-based extinguishers could freeze.
  • Forecourts, yards and industrial sites with flammable liquids or fuel.
  • Workshops with specific metal fire risks (with the right Class D powder).

For outdoor and industrial sites, a 9kg ABC powder is a common choice.

Wheeled Powder Extinguishers

For large risks – such as fuel storage areas, forecourts, large industrial sites and farms – wheeled powder extinguishers carry much more powder on a trolley, with a hose to direct it. They usually come in 25kg, 50kg and 100kg sizes, with 50kg the most common. They're very effective, but less common in the UK than in the rest of the world – we'd like to see more of them in use.

Gas Fires

With a gas fire, the safest action is to turn off the gas supply and call 999. Putting out the flame while gas is still escaping can lead to an explosion.

Caravans and Vehicles

The UK's main caravan clubs advise against powder extinguishers inside caravans and motorhomes, because of the risk of breathing in the powder in a small space. See Fire Safety for Caravans and Motorhomes.

Servicing

Powder extinguishers need a basic service every year and an extended service (also known as a discharge test) every 5 years. A servicing engineer may advise replacing powder extinguishers that aren't suitable for where they're placed. See Do Fire Extinguishers Need Servicing?.

Worth remembering… your fire risk assessment is what decides what your premises need. This guide is general advice, not a substitute for it.

Not sure what you need? Get in touch with our team – we'll be delighted to help. No pressure. No sales patter.