Last reviewed 3 October 2022

In this feature article, Caroline Raine looks at the current requirements and problems encountered with fire extinguishers.

Historical developments

Over the last twenty years there have been significant changes to the fire extinguisher requirements of the Agreement concerning the International Carriage of Dangerous Goods by Road (ADR) for vehicles carrying dangerous goods, this article reviews the current requirements and problems encountered with fire extinguishers, as well as other related matters.

Until the 2001 edition of ADR, the basic provisions for the number of fire extinguishers to be fitted were one 2kg dry powder or equivalent fire extinguisher for fighting a fire in the cab or engine compartment and an additional one 6kg fire extinguisher. This could be reduced to a further one 2kg extinguisher for vehicles with a maximum permitted gross mass of 3.5 tonnes or less.

There were some further exemptions in those days which continue to this day for small loads corresponding to of the ADR and for infectious substances of Class 6.2.

That situation changed in the 2003 edition of the ADR to what we have today, that there are break points for vehicles with a maximum permissible mass of up to 3.5 tonnes, between 3.5 tonnes and 7.5 tonnes and over 7.5 tonnes.

Transport unit maximum permissible mass

Min no of fire extinguishers

Min total capacity per transport unit

Extinguisher suitable for engine or cab fire. At least one with a min capacity of

Additional extinguisher(s) requirement. At least one extinguisher shall have a min capacity of

3.5 tonnes





>3.5 tonnes

≤7.5 tonnes





>7.5 tonnes





The capacities are for dry powder (or an equivalent capacity for any other suitable extinguishing agent).

Lengthy transitional periods were granted for vehicle operators to increase the number of fire extinguishers but these have long since ended.


There are a few exemptions concerning fire extinguishers which should be considered.

  • reminds us that no matter how big the vehicle is, even a 44 tonner, only one 2kg extinguisher is required for a vehicle carrying a load within the exemptions.

  • Special Operating Provision S3 exempts vehicles from the need for the full set of fire extinguishers, allowing one 2kg extinguisher to suffice. This applies to the four UN numbers of Class 6.2, ie UN 2814, UN 2900, UN 2191 and UN 3373. At one time this exemption went so far as to say that the extinguishers fitted to vehicles carrying these substances were exempted from the need for an examination but that has long since been removed so that even these must be subjected to this routine.

Fire extinguishers and the, and exemptions

It is implicit that if the carriage conforms to and complies with the exemptions in, and of ADR, then fire extinguishers are not required.

Fire extinguishers, Excepted Quantities and Limited Quantities

It is worth mentioning that the fire extinguisher requirements of ADR do not apply to vehicles carrying exclusively Excepted Quantities nor those carrying Limited Quantities. For Excepted Quantities, this is made clear in and for Limited Quantities it is made clear by 3.4.1 (h) which only makes applicable from the whole of part 8. The exemptions for Limited Quantities were revised in the 2011 edition of the ADR to make clearer those parts which continue to apply but these changes do not affect Limited Quantities.

Nevertheless, this does not prevent such vehicles being fitted with fire extinguishers. If I were an operator of such vehicles, I would want my vehicles to be fitted with fire extinguishers if only to reduce the risk to my capital investment in them.

Standards — why not just EN3? of ADR states that fire extinguishers shall comply with the relevant requirements of the European standard EN3 Portable fire extinguishers, Part 7 (EN 3-7:2004 + A1:2007). However,, second paragraph, requires all fire extinguishers to bear a mark of compliance with a standard recognised by a Competent Authority, which is puzzling.

Why is a decision by a competent authority required when specifies the standard to which they should comply? A possible reason for this is that the ADR now has over 50 contracting Member States, including Tajikistan and Nigeria which are not European countries; not to mention that there are some North African contracting States. These States would be under no obligation to recognise EN3 and may, indeed, have their own national standards which their Competent Authorities may wish to approve. Nevertheless, the two paragraphs may appear to be somewhat contradictory on this point.

Instructions in Writing — use of fire extinguishers

An important decision was taken during the debates which led to the development of the four-page generic instructions in writing for drivers ( of ADR). This was that drivers should not attempt to fight a fire in the load.

Frequency of inspection — 12 months too long?

At, the ADR requires extinguishers to “bear a mark of compliance with a standard recognised by a competent authority and a mark indicating the date (month and year) of the next inspection or of the maximum permissible period of use”. The ADR does not indicate how long these periods should be.

The general understanding, based on recommendations in standards and based on best practice is that they should be inspected (or taken out of service) after 12 months have elapsed to “guarantee their functional safety”. The containers in which they are held are often insufficiently watertight to stop ingress of water from road spray, etc.

This water may be salty from gritting during wintertime and I have seen many examples of corrosion, particularly to the base. The deterioration, it seems to me, becomes more marked the longer they are in service over six months. You have to remember that any recommendations that say 12 months is the suitable period in standards and so on, are based on the assumption that the extinguishers are on a hook in a warm office where nothing more untoward happens to them than the accumulation of dust. To my mind, formal inspections should take place on vehicle mounted extinguishers at no more than six monthly intervals.

I usually recommend that where there is a possibility of water getting inside the containers a drainage hole is made.

There are other problems with fire extinguishers concerning the marking of the next date of inspection.

  1. Inspectors may only put on the date of last inspection which is the normal practice for office fire extinguishers and not a forward date by when the next inspection should take place. Where the forward date is missing, there is a contravention of the ADR.

  2. The date may be on a label stuck on the outside of the extinguishers. These often suffer from abrasion so that the details become unreadable. This, too, should not be allowed to happen.

  3. They must be sealed to show that they have not been operated. Usually with UK extinguishers this is in the form of a small plastic tie through the handle. These often become broken, especially on the 2kg extinguisher if it is in the cab, depending on where it has been installed.

Examine weekly/shake up?

Good operators will ensure for example, that their drivers are checking the extinguishers regularly, ie weekly, to ensure that they:

  • remain pressurised (tell-tale indicator in the green)

  • are in date with the date of next inspection clearly visible

  • are sealed

  • have not been accidentally discharged.

It is not uncommon to find that externally mounted (larger) extinguishers self-discharge through all the jolting they suffer.

Dry powder extinguishers may suffer from compacting of the extinguishant. As part of the weekly checks, drivers should be told to invert them (once) and then to shake them up.

Fixed in place — a loose canon in the cab?

I have seen many 2kg extinguishers in cabs of vehicles which have not been properly installed. Unsecured, these could become a loose canon in the cab in an accident and cause physical harm to the vehicle crew.

Accessibility vs. theft

The ADR requires fire extinguishers to be installed “in such a way that they are easily accessible”. I have seen the small extinguishers located under the passenger seat in cabs of vehicles, on the rear wall where the driver would have to clamber over the bed in a sleeper-cab, under the bed and even in a sealed box. This sort of thing should not be accepted. Remember, the small extinguisher may actually save a driver’s life if he or she can get hold of it easily and quickly.

Many operators are concerned that externally mounted fire extinguishers may be stolen. Precautions may be taken to reduce this risk such as by locking them in their container or at least sealing them with plastic ties. They may also be mounted on the vehicles in a less easily accessible place. Recently I saw two 6kg extinguishers mounted on the outside rear wall of the cab of a tractor unit towing a box van. The tractor unit was fitted with fairings to reduce drag between the back of the tractor unit and the semi-trailer. These were far from accessible in my opinion and the operator would be well advised to reconsider where they had been mounted.


Statistics published in the UK concerning roadside inspections show that by far the most frequent failings concern fire extinguishers. Either they:

  • are missing or are insufficient in quantity

  • are out-of-date

  • are depressurised

  • have broken seals.

DGSAs acting for vehicle operators would do well to pay lots of attention to fire extinguishers!


  • The requirements for the numbers and types of fire extinguishers to be carried on a vehicle are clearly outlined in ADR.

  • Despite this many still get it wrong carrying incorrect quantities, have them out of date or missing entirely.

  • Fire extinguishers are important and can save lives (not to mention saving a fine or two!).

  • Check them and make sure you have it right — if you are in any doubt get in touch with your company’s Dangerous Goods Safety Advisor (DGSA).