chimneys, pipe defined in 1909 yearchimneys, pipe - Chimneys, Pipe;
chimneys, pipe - No one can deny that for certain purposes a great convenience is effected by the use of sheet-iron pipe for the conveyance of smoke from a stove, or from a portable cooking-range, etc., in instances where a brick chimney is not conveniently near. It may be that the pipe is carried the whole way as far as is necessary for it to constitute a chimney of itself; but more often this pipe is used to connect the stove with some existing brick chimney not far away; in the same or next room, perhaps.
It is considered a very simple matter to fix up a stove in this way; we have to provide a suitable non-inflammable base, fit the pipe on the nozzle of the stove and carry it to the chimney-breast, there inserting it in a hole prepared to receive it. It is important that the pipe be large enough, and numbers of failures have been due to error in this direction.
Stoves that are always closed - that is to say, cannot have the fire opened except for feeding or stoking - can generally be worked successfully with a smaller-sized chimney (whether pipe or brick) than open grates, but of course a man should never fall into the error of making his chimney of less sire than the nozzle provided on the stove by the maker, With stoves, the whole of the air passing into the chimney has to pass through the fire and become heated and rarefied. This by itself is sufficient to bring about a keen draught. Further than this, there is a total exclusion of cold air, and so the chimney itself is not chilled; and altogether, we as a rule get a draught with a stove that needs to be checked and controlled carefully by means of dampers. Now, the keener the draught the less size the chimney maybe to work effectively. This explains why stoves may have smaller pipes, when of the close description, than any form of open grate or convertible arrangement, which permits air to pass into the chimney without being heated.
With any form of stove that is of a portable character, fixed out in a room, but works with an open fire (under the conditions of an open grate), the pipe that may be used with it should never be less than 9 in., and even larger than this is necessary, if the stove is actually of large size. They really should have pipes equal in size to the chimneys provided by a builder when he builds a house - viz., 9 by 9, or 14 by 9 square.
Makers might well make the nozzles larger; it would be practically impossible to make them too large, and, up to a certain point, the stoves would be decidedly benefited. If an instance occurred in which the pipe had to be carried conspicuously, it would then be time enough to reduce the size to the least limit by means of a reducing piece.
It has to be acknowledged that the unsightliness of the pipe-flue increases in proportion with its increase in size; but, strange to say, no one, at least very few people, think of overcoming the ill-appearance of the pipe by decorating it. A 9-in. pipe, coloured to match its surroundings, has a decidedly better appearance than a 6-in. pipe left its natural black colour, yet everyone seeks to reduce the evil by using a smaller pipe, much to the detriment of the stove.
To decorate these pipes, only water colours or washes can be used - merely the colouring matter, with water, and a little size as a fixative. If a little lime-white be made, and coloured with burnt umber, this will give the pipe as good an appearance as could be desired, and the heat will not affect it nor cause it to peel. The appearance can be further improved by ornamental stencilled bands round the pipe here and there in a darker shade. Of course, a brown shade will not suit all surroundings. It would not agree if the general decorations were blue, but the white wash can be tinted just as may be required. In the latter case a light slate colour might be applicable. A skilled decorator could probably choose his colour so that the pipe in some situations, although in full view, would scarcely be noticed at all.
If we fix a stove in a room, and carry a pipe from it into the chimney breast some few feet away, as Fig. 1, we shall get bad results if the pipe joints are not sound by reason of cold air passing in as indicated by the arrows. The ill results in this instance are two-fold, for we not only get the cooling influence of the air passing in at these fissures, but the draught which we depend upon to pass through or near the fire in the stove, only does so to a lessened extent with proportionately lessened good results.
It matters not how small the crevices may be, they should be tightly stopped. Occasionally a chimney may be of such a height or character that its draught is strong enough to ignore small leakages; that is to say, the draught is of such strength that a leakage merely takes a small proportion of it, and there is still abundantly sufficient passing through the fire to keep it burning properly. A chimney of this efficiency, though, is no excuse for bad pipe joints. Bad joints are evidence of bad workmanship or carelessness.
It is hardly possible to get air-tight joints in iron pipes without the aid of some packing material, and for this purpose nothing excels common glazier's putty. It is necessary to first paint the surfaces before the putty is applied. This insures the putty adhering to the metal surfaces. A very imperfect joint is made without paint. The peculiarity of putty is that it hardens with heat, and after a little time the joint will not only remain sound, but it will be found firm enough to require a genuine effort to unmake it.
Sometimes a portable form of cooking-range is fixed standing out in a room or kitchen. This is done for various reasons: for convenience, or commonly is to avoid interfering with a large existing range. Portable ranges are frequently fixed in front of existing ranges with a pipe-flue carried into the chimney. Now, when a range is used with a pipe-flue, the question of joints is a very important one. With almost any form of portable range the passage that the air or draught has to take from the fire opening to the chimney is so much the reverse of straight or direct that a certain resistance is caused, and a much stronger draught is needed than with stoves with the straight passage through them.
It is probably known to everyone that the direction the draught has to follow in passing through a close fire-range is as indicated by the arrows in Fig. 2. This means that, in the first place, the air has to travel in directions quite contrary to that which it is natural to follow. It was explained earlier that the action brought about by subjecting air to heat causes the warmed air to take a directly ascending direction. We, however, in this cooking-range require the draught (around the oven) to first pass along a horizontal flue, then descend, then travel horizontally again before it can ascend in the slightest degree. In addition to this, these flue-ways are invariably narrow, and this, with the abrupt angles, brings about considerable resistance to the passage of the air and the smoke it conveys. It must also be understood that a sluggish draught will never do for a close fire-range; it may possible work it for one day, but the deposit of soot is so abundant from the dull-burning fire that nothing can be done with the range unless the flues are cleaned daily, and even with this care the range is a very limited success.
It is always necessary, when fitting up stoves and ranges in this way, to see that the joints in these articles themselves are sound. Range-fitters (the men who actually fit the castings together) are so apt to think that all ranges are set in openings with brickwork round them (which goes to stop up all leaky joints), that a deal of carelessness is often introduced. It is also very necessary to see that where the pipe fits on the nozzle of the stove, and also where it enters the chimney breast, are made air-tight. In other words, see that all the air which enters the chimney first passes through the fire. This is strictly necessary. Many a range has been a temporary failure wholly because one of its soot-doors has been left out of place or lost. The failure has been remedied the instant the door has been put in its place, and the opening thus stopped.
This brings to mind the third possible cause of failure in fixing stoves or ranges in this way. This error is in omitting to stop or close the brick chimney off below where the pipe enters it. When we carry a pipe into an existing brick chimney through the chimney breast, it follows that some form of grate or range is at the bottom of this chimney, or it may be that the grate or range has been removed, and a bare opening exists. Whichever may be the case, it is absolutely necessary that all passage of air into the chimney in this direction be stopped. If it is an old-fashioned register grate that is there, the register flap can be tied down, and if necessary jointed with putty (the register can be opened when the chimney has to be swept). If it is an old open range then the open mouth of the chimney over the range must be closed across in an air-tight manner with a sheet of iron. To prevent the removal of this sheet every time the chimney is swept, a well-fitting door must be provided in it for the sweep to operate through. In any case, whatever opening exists at the bottom must be stopped. If a close-fire range exists at the bottom of the chimney, and is not used, then see that the dampers are pushed in tightly, and that no doors are left off, or openings exist.
When it is possible or convenient, it is a good plan to stop the chimney just below where the pipe enters, and only leaving room for a soot door and frame for the removal of soot, as Fig. 3. It may be thought that the omission of some provision to close the chimney at the base is very unusual, but it is far from being the case. Numbers of failures have been due to this cause, and if it is a portable range that has been fixed, it is a failure of a very pronounced character when this oversight occurs. It is so much easier for air to pass up this clear and directly-ascending passage, than it is to pass through a fire and a maze of flues, that the range is almost ignored altogether.
A fault, that is pronounced with iron pipe flues, its rapid loss of heat, or the cooling influence the air has upon it when outside the building, can be obviated very successfully by a covering of some compound that is very poor in conducting heat; a non-conductor as it is commonly called. To make the pipe approach a brick chimney in effectiveness, the covering must be of a nature to absorb and hold heat, as well as to prevent its ready transference through its substance or thickness. Silicate cotton is an exceedingly good material in this respect, but it is a little difficult of application. There are other patented compounds of a cement nature that can be applied very well, one of these being Leroy's composition, a material largely used for covering steam boilers, etc., and is well spoken of. This remedy, however, is seldom resorted to, as the temporary nature of the work does not warrant it, and if this expense can be gone to, then, as a rule, a brick chimney may as well be put up. The cost would be but very little greater.
If it is required to erect a pipe-chimney outside a house, and which is intended to be of a permanent character, then cast-iron pipe or pipe of earthenware material is used. The cast pipe will last an endless period, as its substance, if of good quality, will be 5/16 in. or 3/8 in., and the joints are of a sound and lasting kind. This pipe requires supporting in a thoroughly substantial manner. Earthenware pipe, when used, is the kind that is made for drainage purposes, glazed inside and out. This latter pipe possesses the advantage of nearly approaching brickwork in its composition; in fact, the material of the pipe may be said to be identical with that which constitutes a brick. Earthenware pipes make splendid chimneys but they are somewhat expensive, particularly in the means that have to be adopted to support them. Brick chimneys are now being built with glazed pipe linings, and the result is very satisfactory.
With every kind of pipe-chimney there should be provision made for sweeping. This is effected by means of doors or plugs at the elbows, as Fig. 4, or wherever the pipe takes an abrupt turn. Even if the angle is very obtuse, it should never be arranged for the sweep's brush and rods to push past it. The pipe itself may not be injured by so doing: but there is a tolerable certainty that the joints will be strained after it has happened a few times. The reader will also understand how necessary it is that all doors and such openings in pipes be carefully made, so that when closed no in-leakage of air occurs.
If we have two stoves into one chimney, as Fig. 5, for instance, and both fires are alight, there will be a draught passing through each into the main chimney. There is nothing objectionable in this provided each has its fire alight, and it is understood that both are close stoves (or close fire kitchen ranges). Each will furnish and contribute its supply of heated air and also the hot gases, which go to make the draught themselves, and which also furnish heat to the brickwork in the way that has been explained. Now if we extinguish the fire in one of the appliances, what is the result? It is precisely the same as having a large sized hole in an ordinary chimney by which cold air can pass directly in, and effect all its ill and troublesome results. It will be seen that when we put out the fire in one stove we do not put a stop to the pulling power of the chimney, and consequently cold air will be drawn through this particular stove into the chimney, and seriously affect the activity of the one that is working. The difference is all brought about by having cold air passing into the chimney instead of heated air and hot gases.
The method adopted to prevent this trouble is to provide a well-fitting damper to each pipe or branch chimney. This should be placed somewhere near the stoves where it can be got at easily. When a stove is not in use the damper is closed; but it will be understood that it should be one which when closed will really prevent air passing through. A sliding damper is best. Those dampers commonly used with pipe flues, and which are merely a disc of metal within the pipe and operated by a handle outside, are not satisfactory. They cannot be made to fit the pipe tightly - that is in an air-tight manner, and unless they are most accurately balanced they will not remain as they are set. The draught itself will move them unless they are fitted very precisely.
The other particular points to be considered when working two stoves into one chimney is firstly to see that the chimney itself is of full size. A 9 by 9 chimney will not do this unless it is a high one, with (consequently) a very effective draught, or unless the stoves are only of moderate size. The pipes (or branch chimneys) which connect the stove with the main chimney must both be of full size, the same as if one stove only was connected. The joints in the pipes must be sound, and all the other points already explained have to be thought out.
An unusual experience that occurred to the writer in connection with pipe-chimneys was an instance in which a portable cooking-range of large size was placed in a building for temporary cooking purposes. It was fitted up with a pipe chimney of full height, and correctly erected in all other ways except that the pipe was only 7 in. diameter. This sized pipe was found insufficient, for although the range did manage to cook when the pipe was quite clean, it worked very sluggishly, and this brought about a rapid accumulation of soot. Of course, as the soot accumulated in the pipe so the passage-way became reduced, and altogether it became necessary for something to be done.
Upon examination nothing could be found to account for the inefficient results except the smallness of the pipe, and it was decided that a larger one was needed, and it was suggested that it should be of double the area or size of the existing one. This alteration was left for the owners of the range to do, as they had men and abundance of the necessary stores, but this is where the peculiar part of the work occurred.
It was discovered that there was plenty of 7-in. pipe ready made, but none larger, and it occurred to the engineer, that as a pipe of double the area of a 7-in. pipe was needed, why not use two pipes of this size, instead of making a new pipe for this temporary purpose. This idea was acted upon. The existing 7-in. pipe was disconnected at the range, a short length of larger pipe made with a junction-piece, and placed at that point and a second pipe run up as Fig. 6. (This illustration shows straight pipes for the sake of making the explanation clear. They were not exactly straight, but they ran side by side all the way.)
The result of this arrangement was a most pronounced failure, and until the cause was discovered it was a most difficult failure to account for. All the usual causes were searched for, such as leakages, openings, bad joints, etc., without avail, and the pipes were found to be quite clear. Ultimately it was noticed that what smoke did pass into the chimney only issed from one pipe, and the idea was entertained that the second pipe, for some reason, was refusing to act, and the work was being done by one pipe as before. A moment's thought, however, showed that this theory did not quite meet the case, for the range was working in a much worse manner than when it had one pipe only, and if it was now a case of one pipe being actively working, and the other idle, the results ought at least to have been as good as before, which, however they were not by any means.
It was ultimately discovered that what up-draught existed in one pipe was supplied from the other, The direction of the air or draught in the pipes was as indicated by the arrows in Fig. 7. There was a certain amount of warmed air and gases passing up from the range, but only what would j naturally rise by the fact that they were warm, not sufficient by any means I to work the range. The really active force of the draught was busy in the pipes, down one and up the other, quite ignoring the range below.
A very little consideration shows that this is a very natural result. Where-ever two chimneys exist, it matters not how exactly alike they may be built, one will work differently to the other. In this case one chimney was a little more effective than the other, and instead of drawing its air through a mass of fuel, and through a ramification of oven flues, etc., it naturally preferred to have its supply from the free and open source that the other pipe constituted. It has been explained that the rush of air into a chimney will take place equally through every opening it can find, only showing a preference when one opening is more free from obstruction than another. In this were obtained practically the same as providing a simple opening (instead of another pipe) at the junction piece, as Fig. 7.
It is somewhat strange, but instances have been known where twin chimneys something like this have worked well; but such a result could in no way be relied upon. It should never be attempted, for should results be bad there is no remedying the matter, except by putting a single full-sized chimney.
Sometimes two brick chimneys become joined in this way unintentionally, and cause a deal of trouble. It occurs through the sweep's tools or some other cause, dislodging some of the brickwork which forms the partition between chimneys when they are run up side by side. The displacement of a single brick is sufficient. A fault of this sort is usually very difficult to discover, as it probably means opening the chimney at various points, until the defect is found. Sometimes a workman has become impressed with the idea that this fault exists in a chimney, and he cuts away and does infinite damage, only to discover that the defect does not exist. This should not occur if ordinary care is used in testing the chimney to find the cause of its inefficiency.
The method that can be adopted with a prospect of discovering the fault with certainty is to make a fire in the stove or range that is giving the trouble, and stand by it and watch the results while an assistant places a sack over the top of this particular chimney and afterwards over the chimney-top next to it. Previous to doing this, the chimney-tops should be watched to see the action of the smoke coming from them.
A usual and commonly troublesome phenomenon in connection with sheet-iron pipe chimneys, is the trickling of water down inside them. Sometimes the quantity is really large, and provision has to be made for its escape. This trouble is seldom noticeable with indoor pipes, or with any that are fixed in warm situations. With outside pipes it is more noticeable, particularly if the pipe is a flue to a gas-stove and has no soot within it. When soot is present, its poor heat-conducting properties bring about results somewhat approaching those obtained by covering the pipe with material to conserve its heat. When no rapid cooling influence is manifested, the water difficulty does not present itself.
It is not so generally known as might be that of the different products or results of combustion water is one, and that it is formed very freely indeed. We never notice it with our ordinary grates and stoves, which are worked with brick chimneys, and which are always warm. The water is formed in exceedingly minute particles, so as only to form an extremely thin vapour, and this passes up and out of the chimney with the smoke, as the warmth of the chimney does not permit it to condense.
When the smoke and products of combustion from coal or gas are carried up into a pipe chimney outside a house, the cooling influence of the air through the thin metal causes the water vapour to be condensed, in the same way that steam would be; and the instant this takes place the water ceases to rise with the other products, and falls or trickles down the pipe. Sometimes the quantity of water-vapour and its condensation are such that a small but continuous stream passes down the pipe.
When a pipe gets coated internally with soot, this condensation becomes less, and commonly ceases altogether. The soot is a poor conductor of heat, and the contents of the chimney, the gases and water vapour do not get cooled, and the results are (though in a very limited way) more like those obtained with a brick chimney.
The pipe chimneys attached to gas stoves (of all descriptions) suffer most with the water difficulty in question. With these the pipes always remain clean, and any cooling influence there may be acts upon them very quickly and surely, We may also look for a little more water vapour to result from the combustion of gas than from coal, as the former has hydrogen so abundantly and so free in its constitution, much more so than with coal.
Another feature in connection with pipe chimneys which should always have consideration if coal fuel is to be used is the soot deposit, which occurs more rapidly in these than in brick chimneys owing to the greater cooling effect on the iron pipe of the outside air.
The provision of sweeping-doors at every angle, as was recommended, is particularly necessary for the removal of fallen soot - soot that falls down the vertical pipes and in other ways collects at these points. The falling of soot occurs much more frequently and readily from the smooth surfaces of pipes than from brickwork.
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