Fire Prevention and Fire Extinction Part 11

There ought to be at least half a dozen keys for each engine-house, which should be kept by the firemen, watchmen, and those connected with the establishment, that the necessity of breaking open the door may not occur.

DESCRIPTION OF TOOLS WITH WHICH EACH ENGINE IS PROVIDED.

Having considered the sort of fire-engine which is best adapted for general purposes, I shall now notice the different articles which, in London, are always attached to, and accompany, each engine of this kind:--

7 coils of hose, 40 feet each.

4 bundles of sheepskin and lay-cord.

4 lengths of suction-pipe, each between 6 and 7 feet long.

2 branch pipes.

3 jet pipes or nozzles and an elbow for jet.

3 wrenches for coupling-joints.

2 lamps.

2 lengths of scaling ladder.

1 fire-hook.

60 feet of patent line, and 20 feet of trace line.

1 mattock.

1 shovel.

1 hatchet or pole-axe.

1 saw.

1 iron crow-bar.

1 portable cistern.

1 flat suction strainer.

1 standc.o.c.k, and hook for street plugs.

1 screw wrench.

1 canvas sheet with 10 or 12 rope handles round its edges.

9 canvas buckets.

1 hand-pump with 10 feet of hose and jet pipe.

Of these articles I shall endeavour to give a description as they stand in the above list.

The article of hose being first in order, as well as importance, merits particular attention.

The sort used is leather, made with copper rivets, and is by far the most serviceable and durable hose that I have yet seen.

Manufacturers of this article, however, for a very obvious reason, are not always careful to select that part of the hide which, being firmest, is best adapted for the purpose. Indeed, I have known several instances wherein nearly the whole hide has been cut up and made into hose, without any selection whatever. The effect of this is very prejudicial. The loose parts of the hide soon stretch and weaken, and while, by stretching, the diameter of the pipe is increased, the pressure of the water, in consequence, becomes greater on that than on any other part of the hose, which is thereby rendered more liable to give way at such places.

Hose are frequently made narrow in the middle, and, in order to fit the coupling-joints, wide at the extremities--a practice which lessens their capability of conveying a given quant.i.ty of water, in proportion to the difference of the area of the section of the diameters at the extremity and the middle part.

In order to make them fit the coupling-joints, when carelessly widened too much, I have frequently seen them stuffed up with brown paper, and in that case they almost invariably give way, the folds of the paper destroying the hold which the leather would otherwise have of the ridges made on the ends of the coupling-joints.

In order to avoid all these faults and defects, the riveted hose used are made in the following manner:--

The leather is nine and five-eighths inches broad (that being the breadth required for coupling-joints of two and a half inches diameter of clear water-way), and levelled to the proper uniform thickness. The leather used is taken from hides of the very best description, perfectly free from flesh-cuts, warble-holes, or any other blemish, and stuffed as high as possible.[M] Not more than four breadths are taken from each hide, and none of the soft parts about the neck, shoulders, or belly are used. No piece of leather is less than four feet long.

The leather is gauged to the exact breadth, and holes punched in it for the rivets. In the operation of punching, great care must be taken to make the holes on each side of the leather exactly opposite to each other. If this precaution be not attended to, the seam when riveted takes a spiral direction on the hose, which the heads of the rivets are very apt to cut at the folds. Care must also be taken that the leather is equally stretched on both sides, otherwise the number of holes on the opposite sides may be unequal. The ends are then cut at an angle of thirty-seven degrees; if cut at a greater angle, the cross-joint will be too short, and if at a smaller, the leather will be wasted. This must, however, be regulated in some degree by the number of holes in the cross-joint, as the angle must be altered a little if the holes at that part do not fit exactly with the holes along the side.

The different pieces of leather necessary to form one length, or forty feet of hose, are riveted together by the ends.

Straps of leather, three inches broad, are then riveted across the pipe, ten feet apart, to form loops for the purpose of handing or making fast the hose when full of water. The leather is then laid along a bench, and a bar of iron, from eight to ten feet long, three inches broad, and one inch thick, with the corners rounded off, is laid above it. The rivets are next put into the holes on one side of the leather, along the whole length of the iron bar. The holes on the other side are then brought over them, and the washers put on the points of the rivets, and struck down with a hollow punch. The points of the rivets are then riveted down over the washers, and finished with a setting punch. The bar of iron is drawn along, and the same operation repeated till the length of the hose be finished.

The rivets and washers should be made of the best wrought copper, and must be well tinned before being used.

Some objections have been made to riveted hose on account of the alleged difficulty of repairing them; but this is not so serious a matter as may at first view appear. Indeed, they very seldom require any repairs, and when they do, the process is not difficult. If any of the rivets be damaged, as many must be taken out as will make room for the free admission of the hand. A small flat mandrel being introduced into the hose, the new rivets are put into the leather, and riveted up the same as new pipe; the mandrel is then shaken out at the end.

If the leather be damaged, it may be repaired either by cutting out the piece, and making a new joint, or by riveting a piece of leather upon the hole.

The manner of attaching the hose to the coupling-joint is also a matter of very considerable importance. If a joint come off when the engine is in operation, a whole length of hose is rendered useless for the time, and a considerable delay incurred in getting it detached, and another subst.i.tuted.

To prevent this, the hose ought to fit as tightly as possible to the coupling-joint, without any packing. In riveted hose, a piece of leather, thinned down to the proper size, should be put on to make up the void which the thick edge of the leather next the rivet necessarily leaves; the hose should then be tied to the coupling-joint as firmly as possible with the best annealed copper wire, No. 16 gauge.

When the hose are completely finished in this manner they are proved by a proving-pump, and if they stand a pressure of two hundred feet of water they are considered fit for service. I may also add, that when any piece of hose has been under repair it is proved in the same manner before it is deemed trustworthy.

The proving of the hose is of very considerable importance, and the method of doing so which I have mentioned is greatly superior to the old plan of proving them on an engine or fire-c.o.c.k. By the latter method, no certain measure can be obtained by which the pressure can be calculated. In the first place it must depend on the relative height of the reservoir from whence the water is obtained and that of the fire-c.o.c.k where the experiment is made; and as the supply of water drawn from the pipes by the inhabitants may be different on different days of the week and even in different hours of the day, it is quite evident that by this method no certain rule can be formed for the purpose required, the pressure being affected by the quant.i.ty of water drawn at the time.

The method of proving by an engine is considerably better than this; but when a proving-pump can be obtained it is infinitely better than either. One disadvantage of an engine is, that it requires a considerable number of men; but even the proof, that of throwing the water to a given height on the gable of a house or other height, is not always a test of the sufficiency of the hose. As the temperature is low or high, the wind fresh or light, the degree of pressure on the hose in throwing the water to the required height will be greater or less. Indeed, in high winds it is a matter of extreme difficulty to throw the water to any considerable height.

With an engine of 7-inch barrels and 7-inch stroke, fitted with eighty feet of 2-3/8-inch hose, I have found from several experiments that when the water is thrown seventy-five feet high, the pressure on the hose is equal to one hundred feet. The same engine, with 160 feet of hose, and the branch-pipe raised fifty feet above the level of the engine, when the water was thrown fifty-six feet from the branch, occasioned a pressure equal to 130 feet on the hose. From these experiments, I am convinced that the pressure will not be equal to 200 feet, except in very extreme cases, or when some obstacle gets into the jet pipe.

I tried the extreme strength of a piece of riveted hose 4 feet long and 2-3/8 inches diameter, and found that it did not burst till the pressure increased to 500 feet; and when it gave way the leather was fairly torn along the rivet-holes.

Every possible care should be taken to keep the hose soft and pliable, and to prevent its being affected by mildew. After being used, in order to dry them equally they should be hung up by the centre, with the two ends hanging down, until half dry. They should then be taken down and rubbed over with a composition of bees'-wax, tallow, and neats-foot oil,[N] and again hung up to allow the grease to sink into the leather. When the hose appear to be dry they should be a second time rubbed with the composition, and then coiled up for use. In order that the hose undergoing the operation of greasing may not be disturbed or used till in a fit state, it is better to have a double set, and in this way, while one set is in grease the other is in the engine ready and fit for service. More time can also be taken for any repairs which may be necessary, and they will in consequence be more carefully done, and at fires where a great length of hose is required the spare set will always be available. When the weather is damp, and the hose cannot be dried so as to be fit for greasing in two or three days, a stove should be put into the room in order to facilitate the process. The greatest care, however, must be taken in the use of artificial heat. The whole apartment should be kept of one equal temperature, which ought never to be higher than is requisite to dry the hose for greasing in about forty hours.

_Coupling-joints._[O]--So much of the efficiency and duration of the hose depend on the proper form given to the bra.s.s coupling-joints, that I deem it useful to give a detailed description, both of those generally made use of and of those adopted by the Edinburgh fire-establishment, and also to point out their various defects and advantages.

[Ill.u.s.tration: FIG. 3. Old Coupling]

Fig. 3 is the construction commonly made by engine-makers. Its defects are as follows:--From the form of the furrows and ridges where the leather is tied it does not hold on well against a force tending to pull the hose off end-ways; screw-nails are therefore often employed, as at A, to secure the hose on the bra.s.s. The points of these nails always protrude more or less into the inside of the joint, and materially impede the current of water. The mouths of the joints are also turned outwards, and form a shoulder, as at B. The intention of this is probably to a.s.sist in securing the leather in its place, and to prevent the lapping from slipping. The effects of it are as follows:--First, from the leather being strained over this projection, it becomes liable to be cut by every accidental injury, and very soon cracks and gives way, when a portion must be cut off and a fresh fixing made; second, the leather being stretched over the projection, does not fit the other part of the joint, and must be loose or filled up with pieces of leather, or, as is sometimes done, with brown paper; third, the irregularity of the calibre of the conduit which this shoulder occasions diminishes the performance of the engine.

[Ill.u.s.tration: FIG. 4. New Coupling]

Fig. 4 is the coupling-joint adopted in Edinburgh. The furrows at the tying place are shallow, but their edges present a powerful obstacle to the slipping of the leather. No screw-nails are employed, nor is there any shoulder, as at B; there is therefore no impediment to or variation in the velocity of the current, as the calibres of the coupling joints and of the hose are so nearly uniform. It will be seen also that as the lapping projects above the leather this latter can never be injured by falls or rubbing on the ground.

Another great advantage attending the joints used here is the manner in which their screws are finished. On examining the figure minutely, it will be observed that the male-screw ends in a cylinder of the diameter of the _bottom_ of its thread, consequently of the diameter of the top of the thread of the female-screw. The effect of this is, that, when the screws are brought together, the cylindric portion serves as a guide to the threads, and the most inexperienced person cannot fail to make them catch fair at the first trial. The advantage of this in the circ.u.mstances attending fires is obvious.

These joints, although requiring three or four turns to close them up, yet as it is only the ring D which requires to be turned, it can easily be done with the hand alone without the use of wrenches.

Although, when the whole length of hose has been jointed, it may be as well to send a man with a pair of wrenches to set the joints firm; this, however, is by no means absolutely necessary; if the joints are kept in proper order a man can secure them sufficiently with the hand.

There is also a facility in taking turns out of the hose, which no other but a swivel joint affords. By slackening a single turn any twist may be taken out, without undoing the joint or stopping the engine, while, from the number of turns required to close the joints, there is no chance of the screw being by any accident undone. In order to prevent the threads from being easily damaged, they should be of a pretty large size, not more than five or six to the inch. For the same reason also the thread should be a little rounded.

As it sometimes happens that the screws are damaged by falling on the street, or by heavy bodies striking them, whenever the hose have been used the joints should be tried by a steel gauge-screw, to be kept for that purpose. This ought to be particularly attended to, as, on arriving at a fire, it is rather an awkward time to discover that a joint has been damaged, while the delay thus occasioned may be attended with very serious consequences.

_Four Bundles of Sheepskin and Lay-cord._--These are simply four or five stripes of sheepskin, each about three or four inches broad. When a leak occurs in a length of hose which cannot be easily replaced at the time, one or more pieces of sheepskin are wrapt tightly over the leak and tied firmly with a piece of cord. This is but an indifferent method of mending, but I do not know of any other which can be so readily applied with the same effect. If another length of hose can be subst.i.tuted for the leaky one it is better to do so; but that is not always at hand, nor does it always happen that time can be spared for the purpose.

_Four Lengths of Suction-pipe._--These are generally made of leather, riveted tightly over a spiral worm of hoop-iron, about three-quarters of an inch broad, a piece of tarred canvas being placed between the worm and the leather. They are usually made from six to eight feet long, with a copper strainer screwed on the farther end, to prevent as much as possible any mud or dirt from getting into the engine with the water. It is of advantage to carry four lengths of suction-pipe, as they can be joined to reach the water; if one is damaged the others will still be serviceable.

The suction-pipes are more troublesome to rivet than the common hose, and are done in the following manner:--After the joints are fixed on the spiral worm, and it is covered with the tarred canvas, an iron mandrel longer than the worm is put through it, the edge being rounded to the circle of the inside of the worm. The projecting ends of the mandrel are supported to allow the worm to lie quite clear. One end of the mandrel has a check, that the bra.s.s joint may not prevent the worm from lying flat on the mandrel. The leather is then put over the worm, and the rivets being put into one side, a small thin mandrel is laid over the canvas and the rivets struck down upon it. If the small mandrel be not used the heads of the rivets are apt to lie unequally on the worm.