Fighting the
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FIRE _Menace
DESTRUCTIVE as a fire is in itself, the damage caused in getting it under control may be even worse. The fire brigade cannot be fussy, and often has to attack a section of a building not immediately menaced in order to prevent the flames from spreading, because when a fire gains a firm hold, water has little chance of reaching the structure or material that is burning.
The modern method of dealing with certain types of fire is by chemical appliances, the object being to deprive the fire of the oxygen needed for its combustion. There are, however, certain materials which give off their own oxygen, and so combustion can be supported despite the application of de-oxydizing agents. Celluloid is one example of such a material, and a fire involving large quantities of it is a difficult proposition to tackle.
As with illness; prevention is better than cure, and although fires occur in spite of every precaution, there are many measures which can be taken, not only to
reduce the risk, but to hold a fire in check should one develop. First, I will set out a few of the more general causes of fire.
(I) Matebes.—A glowing match thrown amongst oily cotton waste has caused more than one fire.
(2) Smoking.—This should never be permitted in the vicinity of highly inflammable substances. Whilst smoking is now permitted in many works, it is a wise precaution not to allow it in garages.
(3) Cigarette Ends.—Always see that your cigarette end is properly stubbed out before throwing it away. When knocking out a pipe, stamp on the ash or the glowing tobacco.
(4) Rubbish.—The gutterings of garages and other buildings should be kipt clear of paper, dry leaves, birds' nests or other similar material. Should a spark start a fire in a guttering, it may attain dangerous proportions before being discovered.
(5) Naked Lights.—Whilst it should be obvious that . naked lights in any form should not be allowed near petrol .pumps, many people are far too casual in this direction. It is of no use to plaster the premises with "No Smoking" notices unless the instruction be enforced.
(6) Electric Wiring.—Many fires are caused by neglecting faulty electric switches, failing to treat " live " but probably unconnected wires correctly, and the use of fuse wire of the incorrect type or gauge.
(7) Gas.—Swinging gas brackets are a great danger unless they are against bare stone walls. If you have to search for a gas leak, use soapy water.
(8) Oil Stores.—These should be kept as clean as a dairy; milk will not burn, but okl will. There is no excuse for allowing the floor to become oil sodden.
The foregoing represents but a small proportion of the possible causes of fire and means for spreading it in works and garages. According to a representative report issued some time ago by the London County Council's fire brigade, lighted material, such as matches and cigarettes, carelessly thrown away was directly responsible for 28.2 per cent. of fires; sparks, 13.1 per cent.; electricity—various causes-9.3 per cent.; gas— various causes-5.0 per cent. It is obvious from these figures that the biggest single percentage-28.2 per cent. —is attributable to carelessness.
Generally speaking, the principles of extinguishing a fire may be divided into (a) cooling down to a point where combustion ceases, and (b) smothering by cutting off, or diluting, the air which supplies the oxygen to support combustion.
In order to establish the principle of extinction which should be applied, it is necessary to consider and classify the nature of the material which has to be dealt with, and a broad classification is as follows:—(1) Freely burning or carbonaceous substances, such as wood, paper, fabrics and coal; (2) highly inflammable liquids, such as fats, waxes, oils, petrol, paints and varnishes; and (3) electrical fires caused by short circuits, overheating, fusing, and so on.
In the case of the first-mentioned, the burning materials tend to char and become incandescent if left to burn. They may reach a high temperature throughout their mass. Generally speaking, the most effective method of subduing such a fire is by cooling.
Highly inflammable liquids, solids and semi-solids burn only on the surface, the mass remaining comparatively cool during the early stages of an outbreak, For this reason, the smothering or air-dilution method is applicable, as it is really a question of dealing with burning gases.
Fires caused by electrical faults may become complex, because, whilst the outbreak may start in a motor which is not made of freely burning material, the fire
may easily involve such material. Then, again, the application of water in the case of an electrical fire may have serious consequences for the fire fighter, as the current may pass back through the column of water. Ile medium used must be a non-conductor, and the ;mothering method should, of course, be.adopted.
When the fire is such as to call for the cooling-down method, water is the medium generally employed, and, despite its universal availability, it is not always that one finds suitable supplies or arrangements made to this end.
To stop or arrest a fire in its initial stages, fire buckets may serve, but a more useful first-aid appliance is found in the soda-acid type of chemical fire extinguisher. The liquid it projects is mainly water, which issues as a powerful jet under the influence of the. pressure of the CO, gas. This is generated by the interaction of the sulphuric acid and bicarbonate of soda solution with which such a type of extinguisher is usually charged.
Quite a small hand extinguisher will throw a 30-ft. to 35-ft. jet, so that a fire which cannot be approached with buckets of water can be attacked with some effect. Of course, the capacity of such an extinguisher is comparatively small, being from about 10 pints to 2 gallons.
Large types are available up to about 34 gallons capacity, and may be so designed as to be wheeled to the scene of the fire on a self-contained carrier. Such a piece of apparatus will direct a powerful jet for a distance of 60 ft. without manual labour.
Whilst such equipment, as mentioned, may well prove effective in putting out the fire, it is not intended for application to a blaze, which, from observation, is obviously work for the fire brigade, with its more-powerful apparatus.
In dealing with fires in which highly inflammable liquids are involved, not only is water ineffective, but its use may prove to be dangerous. The reason is that as the water is heavier than the burning liquid, it sinks below it and serves as a carrier to spread the fire. The smothering method is, therefore, adopted, in connection with which the media most generally used are foam, sand, powder, carbon tetrachloride, methyl bromide and carbon dioxide.
The basic types of foam used for fire-extinguishing purposes are known as being chemical and mechanical or air foam. Chemical foam is produced by the agency of interacting chemicals, a mechanical foam depending upon physical action for its production.
A 2-gallon chemical foam extinguisher should produce about 16 gallons of foam, or eight times its volume, its output being governed by the size of the container. In the case of mechanical foam, however, the quantity generated is governed only by the pump or hydrant, and the number of foam-making branch-pipes used. The foam-making compound may be injected into the pump, but the more general method is for the fire-fighter to carry a knapsack tank. Unless it be a big oil installation or similar organization, where one would expect to find a trained fire-fighting team equipped with the more pretentious foam-making appliances, the smaller types of hand extinguisher and manual apparatus should he found adequate.
Wherever there is large quantity of petrol or other highly inflammable liquid or substance stored, it is most desirable that some form of foam extinguisher be kept available for instant use. An advantage of the foammaking branch-pipe is that foam or only water can be used according to the type of fire being dealt with...
These foam-making branch-pipes have a tremendous output. A fire-engine pump delivering 400 gallons per minute at 120 lb. per sq. in., will operate eight F.B.2 size Pyrene foam-making branch-pipes, each capable of producing 450 gallons of foam per minute, a total output of 3,600 gallons per minute.
The point is, however, that the early application of foam to a petrol or similar fire will prove instantly effective, so that even the smallest type of foam extinguisher, if used with dispatch, may easily localize a fire that otherwise might have most serious consequences.
Yet another type of fire extinguisher is that in which carbon dioxide (CO,) forms the smothering medium. Being a non-conductor, this gas can be used with good effect on fires in which there is risk of electrocution. It is specially recommended for treating fires involving ' spray booths, enamelling ovens, oil-filled switchgear, electric transformers and so on. The gas is stored in liquid form in the container of the extinguisher, and, when released, 450 times the volume of the liquid is produced in the form of CO, gas.
Whether the premises concerned be small or large, it is possible, for a small outlay, to ensure a measure of safety against the ravages of fire. The cost of the various pieces of equipment is extremely modest, and for a capital outlay of but a few pounds it is possible to purchase such apparatus as will be capable of dealing with any class of fire, at least in its initial stages.
The following concerns will readily co-operate in giving advice on all matters appertaining to fire protection:—Pyrene Co., Ltd., Great West Road, Brentford; Minimax, Ltd., Feltham; Foamite Firefoam, Ltd, Langley, Bucks; Nuswift Engineering Co., Ltd., Protector Works, Elland, Yorks. The photographs are reproduced by courtesy of the Pyrene Co., Ltd.