Protect Your Unmanned Buildings with Automatic ABC Powder Fire Extinguishers

Unmanned buildings, rooms and even vehicles can be at high risk of fire. As there is no one around to notice, react and respond appropriately, the fire can spread and cause untold damage — to the environment, your site, your equipment and your stock.

If you manage any unmanned or currently unoccupied sites — such as server rooms, transformer buildings, mainframe clean rooms, chemical storage facilities, or you have an infrequently visited boat, for example — you absolutely need to install, inspect and maintain a well-designed automatic fire extinguisher system that is appropriate to the likely class of fire.

What is an automatic fire extinguisher system?

Automatic fire extinguishers work to control and eliminate fires without manual intervention. This kind of extinguisher can be used to great effect in unmanned sites, or for when buildings are untenanted or left empty with equipment running. As the fire suppression system is triggered — usually by heat, but also flames or smoke in some cases — the extinguisher’s contents are  dispersed over the affected area, and the flames die out.

Historically, automatic extinguishers would water or, more recently, dispense a mist. Unfortunately, though, water is not effective in tackling oil and fuel-based fires, or electrical fires (classes B and C). As a result, dry powder extinguishers are now the standard — they have the added benefit of causing only very minimal damage to the site, as opposed to the sometimes extensive damage that water can cause.

What is ABC powder?

ABC powder is usually a mix of monoammonium phosphate and ammonium sulphate, and can be used to effectively extinguish Class A, Class B and Class C fires — common combustibles like wood or paper, oil and fuels and electrical fires, respectively. The dry powder extinguisher achieves this by smothering the fire, stopping the flames from spreading and preventing any heat/fuel/oxygen chain reaction.

The key difference between ABC and standard dry powder fire extinguishers is that the latter are not as effective on class A fires, as they frequently allow combustibles to re-ignite.

How does an automatic ABC system work?

The ABC powder is contained in a pressurised cylinder or container, which is positioned above or next to the likely fire risk. This container is linked to a trigger, typically consisting of a glass bulb with a thermo-sensitive liquid inside. When the liquid reaches a certain temperature (usually around 68°C), the bulb breaks and the container is vented. The powder disperses over the area extremely quickly — between eight and 30 seconds, depending on the capacity of the container — and the enclosed space is covered, suppressing the fire quickly and effectively.

Where should you install an automatic ABC fire extinguisher system?

This kind of extinguisher works best in an enclosed, unmanned or unmonitored space. If you picture a server room or a small boat, for example, there are inherent fire risks. In the first, you have a densely packed array of electrical equipment with the associated heat build-up; in the second you have a fuel store and extensive electrical equipment that could ignite due to temperature changes, poor storage, malicious activity or short-circuits. Both environments can be unmanned for long periods, and a fire in either could be catastrophic — your server room likely contains your most up to date business critical information, and the boat will likely be rendered unusable.

Automatic fire extinguishers also work well for protecting any unoccupied building and larger models are available on the market to suit bigger areas. You will need to install them in all rooms, or at least all rooms that present a greater fire risk, in order to properly protect your property.

Installing an automatic ABC extinguisher system gives you 24/7 fire safety protection, as well as an immediate response — waiting for fire and rescue services can waste valuable time as the fire spreads, destroys and gets out of control.


The capacity you choose is entirely dictated by the size of the space you are protecting. As discussed, these extinguisher systems work best in enclosed spaces, and as a general rule the size of system for the room space is as follows:

  • 1 Kg automatic ABC powder fire extinguisher – for spaces up to 3m2
  • 2 Kg automatic ABC powder fire extinguisher – for spaces up to 6m2
  • 6 Kg automatic ABC powder fire extinguisher – for spaces up to 9m2
  • 10 Kg automatic ABC powder fire extinguisher – for spaces up to 15m2
  • 12 Kg automatic ABC powder fire extinguisher – for spaces up to 18m2

Installation and maintenance

The biggest drawback of this kind of fire response system is that unlike a standard, hand-held extinguisher, you can’t just place it in the room and be done. The system needs to be professionally installed to ensure that it is effective (and to meet BS 5305 relating to the installation and commissioning of fire extinguishers), and to provide the best level of protection.

Maintenance and inspection activity should take place on a scheduled basis, at an absolute minimum every twelve months, but once a quarter where possible.

Other benefits

In addition to round-the-clock, fast emergency response, automatic ABC fire suppression systems are an affordable option, and can also reduce fire insurance premiums in many cases.

As with all health and safety and fire management measures, make sure to check what your obligations are under the relevant health and safety legislation, and consult with a fire safety professional where necessary.

Author Bio: First Mats started life as safety matting specialists, but have since expanded to become a complete industrial and commercial supplies company. The focus of First Mats is to provide safety-focused products that improve the wellbeing of staff through quality approved products, backed up by extensive knowledge.

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