Fire Extinguisher - the right one

Hang on, a fire? When has anyone had their 'Seven' catch fire on a run, or even experienced a fire in the garage or workshop? That it has not happened does not mean that it will not happen. Having seen a friend's 1934 Riley in superb condition and then a week later it was a burned out wreck, I soon had second thoughts.

Petrol vapours, or an electrical fault, may ignite at anytime on a run or at home in the garage. Several members have a workshop and do some welding or paint spraying and probably have a small quantity of petrol or paraffin in an open container for cleaning parts.

In reality we all have a potential fire waiting to happen, so how can we be prepared if it does? Yes, you can go into any motor factors and buy a small hand held extinguisher for about £12, which may seem to be the ideal Christmas present. But is it the correct one for the type of fire, is it of a suitable capacity, what is the shelf life, does it have a gauge to indicate condition, can it be recharged after use, is the size suitable to be carried in the 'Seven', will it 'separate' and be useless at the moment of need? Having the wrong sort of extinguisher, or one that is of incorrect size, could be worse than not having one at all.

I looked at websites and then sought expert advice from Chubb Fire, probably the leading company for extinguisher sales and service, and was soon in contact with their Cornwall representative, who offered the following advice.

fire ext 1 For carrying in the car a 2 litre spray foam extinguisher is recommended, complete with a transport bracket. These should be discharged and refilled every 5 years. No harm would come to the contents under vibration as long as the bracket is fixed securely. The cost of the extinguisher and transport bracket is about £35.00 plus vat. However, the extinguisher measures 405 mm x 112 mm and this is perhaps too large for the 'Seven' interior.

The smaller size 1 kg dry powder extinguisher is 350 mm x 80 mm and can be used on car fires. However these are not recommended for use in confined spaces due to the density of the powder. If it is discharged into the engine compartment a quick jet wash would be required, but if it is discharged into the interior the cleaning up would be a long and labour intensive process.

With a foam extinguisher you can stop and start the operating procedure without losing any pressure once the operating handle is released as the contents will form an airtight seal. With powder extinguishers there is only a short discharge time and you have to empty the entire contents, you cannot have a second go as the pressure will not hold once you operate it. The difference with powder is that once operated the dry powder content is trapped around the seal causing a dropping of pressure to zero even when the operating handle is released. Note that with any partial discharge of an extinguisher you will require a refill and re-pressure.

For anyone who has a workshop the advice is to have a 1 x 6 litre spray foam extinguisher and a 1 x 2 kg CO₂ extinguisher which requires a discharge test every 10 years.

Foam extinguishers are ideal for multi-risk environments, where the source of the fire could be solid materials such as wood or paper, or flammable liquids like petrol or diesel. Spray foam works by cooling fires and sealing the vapours to prevent re-ignition, providing the operator with greater all round safety. The spray nozzle gives a wide coverage and foam is safe if sprayed on electrical equipment.

It seems that the physical size is a difficulty for the small internal dimensions of the pre-Ruby 'Sevens', only the 1 kg extinguisher is likely to fit. However, can we afford not to be safe as a fire in the car could be rather expensive, let alone the loss of use for a few club runs?

As with everything you can take advice and make your choice, and by means of Yellow Pages shop around, but buying an extinguisher at a motor factors without some thought as to what you are buying is not a good idea.

Seek expert advice, buy and correctly fit the right extinguisher.

This article, written by Doug Castle, originally appeared in CA7C Seven Focus in April 2005 pp6-7.

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