Spons' Household Manual / A treasury of domestic receipts and a guide for home management

by Unknown

The causes of explosions at present known are, firstly, stoppage in both the circulating pipes, caused by frost or by the terrible practice of putting stop taps in these pipes, which prevents escape of steam generated in the boiler, and steam must and will escape if it bursts the boiler to effect its release.

Secondly, failure of water supply. This is sometimes caused by a hidden or unnoticed leakage, or in country residences where the water is pumped this failure is not an uncommon thing (but only rarely results in an accident). If the want of water is unnoticed for a time, the boiler will empty itself by evaporation and afterwards become red hot; should the water then run in, steam will be generated so rapidly that the pipe outlets will not be sufficient for its free escape, and the boiler bursts; all this happens in much less time than is occupied in explaining it, in fact so quick that there is no time for escape if any one is unfortunately near; this, however, under ordinary circumstances cannot occur with the No. 1 system.

There is another though rare cause of accident (which, however, once came under the writer’s notice) that may occur with either system, and that is the ends of the circulating pipes nearest the boiler becoming stopped by incrustation; this incrustation, as has been before explained, takes place in the greater proportion of boilers, and also to a less extent in the pipes, especially near the boiler, and in course of time the pipes will both become completely stopped, but the reason that accidents from this cause are rare is that abundant notice is given by the steam making a variety of unpleasant noises and sometimes violent shaking, in forcing its way through the partly closed pipes, but this noise must not always be confounded with the sounds produced when pipes are imperfectly run or “trapped” and contain air, but whenever noises are heard a practical man should be consulted at the earliest convenience, and if a tap is opened and no water should flow, after it has been open say one minute, the fire should be immediately extinguished and kept so until the reason of failure of water is discovered and remedied. No alarm need be experienced at the rumbling noise to be heard when the water is boiling, but this water has no need and should not be permitted to boil; when the noise is heard, 4 or 5 gal. should be drawn off, this will be replaced in the tank or cylinder by the same quantity of cold water, and the temperature will be reduced; the damper which regulates the boiler flue should be out only when the water is cool and requires rapid heating; even then it must not be pulled out so far that the flame, &c., roars as it passes under the boiler, as the boiler will not experience the full benefit of the heat.

It has been suggested by some authorities that to prevent the water in pipes becoming frozen (this may be considered the most likely cause of explosion) a tap or taps should be left a little open at night so that the water is kept in motion; this, however, cannot be relied upon in a really severe frost, and it is also a waste of water, which is a consideration where the supply is by manual power, &c. Another method suggested is to empty the whole apparatus every frosty night; this is a very good plan to save damage to pipes as well as prevent accidents, but there is the doubt that but few would care to practise this on account of the trouble, and there is a serious risk if it is forgotten to turn the water on until after the fire is lighted. Tolerable reliance can be put on felting or casing the pipes, but the most efficient remedy is to see that the boiler is fitted with a safety valve, which, as the name betokens, is a source of safety and most probably of comfort also; if it is not convenient to attach a safety valve direct into the boiler, it should be connected by a short length of pipe, which however is a weakness, as the pipe may eventually be stopped by incrustation, and on that account it should be of good size and should be cleared, if necessary, every time the boiler is opened for cleaning. Safety valves should always be fixed in sight so that they can be tested whenever desired. The working principle of a spring safety valve (which has general preference just now) is, firstly, a brass sealing which closes the opening leading to the boiler and is held in position by a spring and central pin, and the whole works in a strong brass case which is perforated with several good-sized holes; when the valve is fixed, the workman can and does set the spring (generally by a screw-down cap at top) so that it withstands about 3 or 4 lb. more pressure than the boiler is subjected to by the pressure of water; when by any reason an undue pressure is exerted inside the boiler it causes the seating to rise, and the steam and some water escape into the brass case and through the holes above referred to, and the boiler is relieved. The noise occasioned by this escape is very plainly heard, and notice is thus drawn, but the fire need not be extinguished.

It would be a desirable feature if every boiler fixed (except open ones) was provided with a valve, as it is purchasing freedom from risk at a low price (a few shillings only).

There is a common cause of complaint and annoyance in having at some taps to draw off a quantity of cold water that lies stagnant in the service pipe before the hot water can be obtained from the circulation; this is caused by the draw-off service being a long and single pipe, and can be only remedied by “returning” it something after the manner shown in the illustrations, and so cause the water to circulate along it; this trouble is not only a source of annoyance but a practical loss also, as for every quantity of hot water drawn a certain quantity is left in the service to get cold, and this happens every time the tap is used, excepting such taps as are in constant use, and the water only remains stationary 2 or 3 minutes, but this in domestic purposes only applies to the scullery service at certain hours in the day.

It may have come to many people’s notice that when some lever-handle taps are shut a noise and jarring in the pipe ensues; this is caused by the sudden stoppage of the flow of water when the pressure is considerable; when the vertical pressure is say 50 or 60 ft. (height of cistern above the tap) and the tap is opened, the water rushes out and gains a strong momentum; by turning the handle or lever of the tap the stoppage is so sudden that a shock is sustained almost the same as an object falling from a height being suddenly stopped by coming in contact with the ground; this concussion and noise is not only unpleasant but does harm, which is quickly noticeable with light lead pipe, which is either stretched or has protuberances formed upon it, and a continuance of the shocks or really blows will then cause it to split; it will be therefore commonly found that screw-down taps are used with lead pipe where any pressure exists, and the screw-down tap would meet with more favour but for an objectionable feature, which is the number of times it has to be screwed or unscrewed to shut and open it; but there are now made screw-down taps that open or shut with one turn, and these no doubt will come into more general use if found practically good and when the patent expires.

Retarded circulations arise from a variety of causes, amongst which may be mentioned incapacity of the boiler for the work, caused by the boiler not having sufficient heating surface; this is shown by the whole apparatus becoming fully charged with hot water late in the day after several hours firing; the only remedy is to reduce the work the boiler has to do or change the boiler itself. Another cause is by pipes being dipped or trapped. The flow pipe having an inclination or dip downwards, which causes the circulation to become air-locked, this causes noises in the pipes and shakings as the steam is passing or trying to expel the air; this air is eventually expelled, but occurs again when the apparatus is emptied and recharged in boiler cleaning, repairing, &c.; to remedy this the pipes must be traced up and the defect so discovered. Another cause is by incrustation in the pipes; this can be noticed by its gradual growth, also incrustation in boiler, but if boiler is kept clear as referred to earlier in the chapter, the pipes will keep in very fair order. The only remedy for furred pipes is to take them out and by heating and striking to dislodge the deposit; this costs as much almost as renewing the service; with care in regular cleaning it will not occur. Obstructions either stationary or floating are sometimes found in the pipes and retard circulation; these are generally caused by the workmen failing to look through the tubes before fixing them, or the obstruction may be in the form of sediment in rural districts, &c.; the only efficient remedy that can be suggested is to engage the services of an experienced hot-water fitter in any of the cases mentioned, as it lies beyond the power of the householder to remedy them.