T43if DATE DUE ■ ^ ■ *- — - T^nvi TTnsw CAVLOHO rniNTEDlNU-S-A. Cornell University Library The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31 9240046361 1 8 Fifth Edition, March, 1900 Cahall Water Tube Steam Boilers Manufactured by The Aultman & Taylor Machinery Company Mansfield, Ohio Thayer &C Co., Incorporated General Eastern Agents Boston, Tremont Building New York, Taylor Building Philadelphia, Drexel Building Sole Sales Agents Cahall Sales Department Pittsburgh, Pennsylvania o Q J S E tn o S K O < ^ < z <; w CAHALL WATER TUBE BOILER Evolution of Steam Generators THE steady advance toward perfection can well be exemplified in the generation of steam. Some of the older class of engineers can yet remember the struggle between the old externally fired shell boiler and its then young rival, the multi-tubular. The con- test between old-fogyism and advance was bitter, but progress won. Gradually the multi-tubular boiler, with its thin heating surfaces in large areas, demonstrated conclusively its superiority over its cumbersome, extrav- agant rival, and the shell boiler became a thing of the past. Hardly had the battle been won, when the water tube boiler entered the field to contest with the fire tube the right of existence. In the meantime the same dogged obstinacy that had fought against the introduc- tion of the fire tube boiler transferred its allegiance from the discarded externally fired type to the fire tube type, and the war was waged all over again, and again progress won. For years past, in all high grade powei' plants, the water tube boiler has been selected as a matter of course. But in this, as in the evolution of the human species, there is no such thing as rest. There is no point where we can stop and say, " Thus far shalt thou go and no farther." The water tube type of boiler hardly becomes the possessor of the field when another struggle occurs and the contest is on between the vertical and the horizontal water tube. Until within the last ten years the horizontal held the field because it zi'as a water tube boiler ; and a water tube boiler of anj' kind, horizontal or vertical, is so much superior to the fire tube boiler that it naturally survived, being unques- tionably the fittest. But experience during the last decade has shown that types ot water tube boilers may CAHALL WATER TUBE B(3ILER 5 themselves differ from one another in their glory, even as the stars do. The horizontal water tube boiler, although far superior to its predecessor the fire tube, is in its turn being supplanted by the vertical. When the vertical first made its appearance, it in its turn was scoffed at and ridiculed by the fraternity at large, because it was new, different, a strange thing, untried — was looked at as an innovation, and had to fight its way inch by inch into popularity over old-fogyism and prejudice; but the battle is now practically won. The increased circulation, which is positive and unintermit- tent ; the freedom from formation of scale within the tubes in heavy masses, and the freedom from the accumulation of foreign substances outside of the tubes owing to their vertical position ; the great capacity and high efficiency shown in repeated comparative tests between the newcomer and its firmly entrenched rival, have given it the preference to-day that the horizontal water tube boiler held fifteen years ago. The vertical water tube boiler is an unqualified success, and will occupy the field until it in its turn must give way in the future to some new design, even as the others have done in the past. Such is the law of life and progress. It would be interesting to note, if space permitted, the step-by-step evolution of the ^•erti- cal boiler from the crude experiments in which tubes of distorted shapes and different lengths were used, which, though handicapping the vertical type to a very con- siderable extent, still demonstrated in no uncertain wav that, even in spite of these great mechanical faults, the vertical type as a lypc was superior to the horizontal, even with its perfection of mechanical detail, which had been laboriously evolved through a long period. But inventive genius, never sleeping, eliminated feature by feature these mechanical defects, until to-day the verti- cal water tube boiler stands perfected, not only in its CAHALL VERTICAL BOILER WITH CHAIX GRATE STOKER ATTACHED CAHALL WATER TUBE BOILER 7 conception and design, but in its mechanical details, as evidenced by the Cahall Vertical Boiler, manufactured by The Aultman & Taylor Machinery Co., of Mansfield, Ohio. Test after test has been made on this boiler for efficiency, capacity, durability and safety, and from every trial it has emerged with flying colors, until it would seem that the results obtained left nothing to be desired. In the matter of capacity it has repeatedly devel- oped, for long periods of time, more than twice the amount of power for which the boiler was designed. In the point of efficiency it has delivered in dry steam more than 85 per cent, of the theoretical analyzed value of the fuel burned on its grates. In the matter of freedom from scale accumulation it has run for a period of five years without the introduc- tion of a scraping tool in any of its tubes, and at the end of that time shown heating surfaces as clean as the day the boiler was started, although in the same works, side by side with it, using feed water from the same source, containing the same amount of sediment, horizontal water tube boilers have, within a period of one year from their first steaming, had tubes filled solid with scale. As to durability in the same plant above mentioned, through this whole period of five years there has never been one penny expended on the boiler proper for repairs from any cause whatever. Such a record may well cause engineers to wonder how it will be possible for a rival to arise that can equal, much less eclipse, a record like this. o o < Pi o 33 < < Q < o CAHALL WATER TUBE BOILER A Perfect Steam Boiler The late Mr. George^ H. Babcock, of Plainfield, N. J., ex-president of the American vSociety of Mechani- cal Engineers, was probably a closer student of steam boiler design and construction than any other engineer who has lived during the present century. Shortly before his desith he wrote that the result of his engi- neering expedience and scientific investigation for a period of over fifty years in the field of steam boiler practice had ' established twelve requirements of a perfect steam boiler. That any steam generator should combine every one of these points, all engineers of to-day who have no particular "axe to grind" will readily admit, and we unhesitatingly agree with Mr. Babcock in his deductions. Read carefully these twelve requirements, which are, as stated, the result of over fifty years' hard work, study, research and untiring experiment, and then read the description of the Cahall Vertical Water Tube Boiler which follows, and you cannot fail to be impressed with the wonderful fidelity with which this boiler fulfills every one of these absolute essentials : Requirements of a Perfect Steani Boiler 1st. The best materials sanctioned by use, simple in construction, perfect in workmanship, durable in use, and not liable to require early repairs. 2d. A mud drum to receive all impurities deposited from the water in a place removed from the action of the fire. 3d. A steam and water capacity sufficient to pre- vent any fluctuation in pressure or water level. o CAHALL WATER TUBE KOILER II 4th. A large water surface for the disengagement of the steam from the water in order to prevent foaming^ 5th. A constant and thorough circulation of water throughout the boiler, so as to maintain all parts at one temperature. 6th. The_. water, space divided into sections, so arranged that should any section give out, no general explosion can occur, and the destructive effects will be confined to the simple escape of the contents ; with large and free passages between the different sections to equalize the water line and pressure in all. --— • 7th. A great excess of strength over any legitimate strain ; so constructed as not to be liable to be strained by unequal expansion, and, if possible, no joints exposed to the direct action of the fire. 8th. A combustion chamber, so arranged that the combustion oTgases commenced in the furnace may be completed before the escape to the chimney. 9th. The heating surface as nearly as possible at right angles to the currents of heated gases, and so as to break up the currents and extract the entire available heat therefrom. loth. All parts readily accessible for cleaning and repairs. This is a point of the greatest importance as regards safety and economy. iith. Proportioned for the work to be done, and capable of working to its full rated capacity with the highest economy. 12th. The very best gauges, safety valves, and other fixtures. u Q ►J •J a w Ik M ^ z OS t o , is t o ■S^ o s ^ D o: & <: ^ o c < a CO w CM D Q P < CO M O K CAHALL WATER TUBE BOILER 13 The Vertical Water Tube Boiler Manufactured by The Aultman & Taylor Machin- ery Co., of Mansfield, Ohio, and for which the Cahall Sales Department, Pittsburgh, Pa., are sole agents in the United States, consists of two drums arranged one above the other, made of best mild open hearth flange steel, and connected with four-inch lap-welded best charcoal iron tubes. These tubes are vertical, are per- fectly straight throughout their entire length, and are expanded into the drums at each end, making lasting and absolutely tight joints. The upper or steam drum has an opening through its center for the exit of waste gases. These gases, although reduced to a very low temperature in passing through the closely grouped tubes of the boiler, will impart most of their retained surplus heat to the metal sides of the passage through this upper drum, thereby tending to slightly superheat the steam in the chamber above. The water line in the upper drum is about two feet above the bottom of the drum, the drum itself being about seven feet high in the clear inside, leaving a space of five feet between the surface of the water and the point at which the steam is drawn off from the boilers, which prevents the carrying over of water with the steam, either in the form of supersaturation or mechanical entrainment. An external circulating pipe comes out from the upper or steam drum, just below the water level, and is carried downward, outside the brick work, to a point just below the tube sheet of the lower drum, where it enters that drum. There being no steam whatever in this external circulating pipe, and no possibility of making any, and there being, in the tubes connecting MAIN BOILKR HOUSE, APOLLO IRON & STKEL CO. CONTAININ(i 1(1,111111 H. P. CAHALL VERTICAL WATER TUBE BOILERS Cahall water tuhe ]!iiiler 15 the two drums, steam in greater or less proportions, the result is (the volume in the external pipe having a considerably greater specific gravity than the mixture of steam and water in the tubes) a very rapid, positive circula- tion in one direction ; the water in the tubes connecting the drums ascending to the steam drum, delivers this mixture of water and steam there, where- upon the steam separates from the water, and after traveling the space of five feet from the water level to the top of the drum, escapes, and the water which is left behind enters the circulating pipe and is carried down to the mud drum and again arises with its mixture of steam. The boiler rests upon four iron brackets riveted to lower, or mud drum, supported upon four piers of the foundation, the entire structure standing without contact with the brick work, allowing the boiler every freedom for expansion without in any way straining the brick setting. In all places where pipe connections are made to the boilers through the walls, they are encased in expansion boxes. Circulattnj^ Pipes Vertical Ho on Cahall iler o r^- J < r^ CJ < ►J ■< 3 t^ o •A < _.mitii.^,— CAHALL WATER TUBE BOILER I9 upper drum (which is sufficiently large to admit of a man standing upright and walking around in it) in five minutes examine the condition of every tube in the boiler, and in case scale or sediment is discovered in any of them, can in a few minutes run a scraper through such tubes and render them perfectly clean. The scraper used for cleaning these tubes is made in sections a trifle less than six feet long. Four of these sections are used, and the man who is cleaning the boiler takes them into the upper drum and pushes the first section down as far as it will go, then connects the second sec- tion to that, and continues doing this until the scraper has gone entirely through the tube, forcing any scale matter that may have deposited on the sides of the tube straight through to the bottom drum. This form of scraper is very easily handled and takes little time to connect or disconnect, and will thoroughly remove every particle of scale that may form. It will be found in actual practice that the use of the scraper in these boilers will be very seldom necessary, as, for instance, many boilers in use for over five years have never, up to and including the present time, had a cleaner in a single tube. Right here it might be well to mention that very seldom is a tube in a water tube boiler burnt out on account of a general or uniform deposit of scale on its surface. Most tubes failing are burned because a light scale having accumulated in the tubes, patches of it become loose and fall to the bottom of the tube, and remain there, because the tube lies in an approximately horizontal position. There are many instances where boiler tubes scale uniformly to the thickness of an inch, without any loss from burning. On the other hand, a single patch of scale less than an inch in diameter and one-eighth inch thick, on an otherwise clean tube, frequently causes the tube to burn out at the point 8 ^ o =; •J X CAHALL WATER TUBE BOILER where the scale is deposited. It will be seen that, from the arrangement of the tubes in the Cahall boiler, any scale that might loosen will at once fall to the mud drum at the bottom, and, if small enough, will be blown out through the blow-off pipe ; if too large for this, it can be removed through the man-hole on regular cleaning day. As the entire lower drum is removed from direct contact with the fire, the presence of scale in this drum can act in no way to the detriment of the boiler, as, the fire not being in contact with the drum, it could not burn, even were the drum allowed to become half filled with scale. Ample provisions are made for removing defective tubes from the boiler, in the following manner: An examination of the steam-drum cut will show the reader that in the upper or top head of the steam drum there are placed hand holes, which are closed by means of plate, yoke and bolt, in the usual manner ; that there are, in addition, other holes used, one for the steam pipe connection, the other for the pop valve connections. By means of these openings a tube needing removal, after having been cut loose from the tube sheets can be pushed up through the tube hole from which it has just been cut and through the most convenient of these openings in the top head, and removed from the boiler. The new tube to replace the defective tube is passed into the boiler through the same openings. In the waste heat type of boiler the same provisions are made, and in addition, as the whole top of the steam drum is completely covered by the cone-shaped hood forming the base of the smoke stack, there are placed in the sides of the cone, at proper distances, openings, closed by doors, through which the tubes, after having been pushed up through the drum, are taken out and the new ones passed back again, without interfering at all with the stack. ■f. o a: < H -J " a S > O s w 25 CAHALL WATER TUBE BOILER 23 All materials furnished in and with this boiler are of the very best ; the workmanship is of the highest grade known to the boiler-making art ; the safety valves are all of the latest improved pop type, with nickel seats ; the fittings and valves are all specially designed, extra heavy, and the best that money can procure. We are determined to make this the world's standard water tube boiler, and no care or expense will be spared to make it such. The external combustion chamber, roofed with a heavy fire-brick arch, becomes incandescent shortly after the boiler is fired, and radiates directly on top of the green coal its intense heat, and enables the Cahall boiler to be operated with less smoke than any other boiler can with the ordinary smoke-preventing devices attached. Furthermore, owing to the direct upward passage of all gases, and full, free openings, it can with a comparatively short stack obtain in the furnace a draft pressure that is not possible with most other boilers. For instance, in tests made with a stack only 50 feet high a draft pressure in the furnace of over one-half inch was attained, which is a result that we doubt could be obtained from any other water tube boiler with a stack 100 feet high. This heavy draft causes a very rapid combustion of fuel per square foot of grate, with the consequent high initial temperature of gases which all engineers admit is the primal requisite to efficiency in boiler practice. To sum up, we furnish a boiler equaled by none built in quality of material, in excellence of workman- ship, in surplus capacity per nominal unit, in evaporative efficiency, and in ease of examination and cleaning. a: ■I. = < r- CAHALL WATER TUBE BOILER 25 Cahall Boilers for Blast Furnace Gases From the foregoing description it is noticeable that this boiler is most admirably adapted for the use of blast furnace gases ; the external combustion chamber, imparting as it does its intense heat to the entering gases, puts them in a condition that enables them to take fire instantly and burn freely and quickly. None of the heavy metal sheets of the boiler being in contact with these flames, the intense heat thus generated can have no harmful effect, as it is thrown directly against the very thin metal surfaces of the tubes, the heat from which is readily absorbed by the water contained therein, in the thin columns into which it is subdivided. In tests of boilers using blast furnace gases for fuel, an initial temperature of combustion of over 3,000 degrees has been obtained, and yet the gases are brought so thor- oughly in contact with these thin heating surfaces that by the time they reach the opening in the upper drum their temperature is reduced to between 400 and 500 degrees, thus giving an efficiency higher than has ever been obtained by boilers of any type using blast furnace gases as fuel. These highly heated gases, impinging directly on the thin heating surfaces, of course make steam with extreme rapidity, and the heating surface in these boilers being figured more conservatively than in that of any other water tube boiler, allows a great excess over the nominal or rated capacity of the boilers to be taken from them without materially affecting the economy. The use of fine ores is becoming more general every year, their low first cost more than counterbalancing the disadvantages which are claimed by some furnacemen ►J Pi < < o u J O a C 2; CAHALL WATER TUBE BOILER 2/ to result from their use. One of the principal among these is the fact that a large quantity of fine ore is carried over with the gases to the boilers. Where boilers with horizontal or approximately horizontal heating surfaces are used, this really becomes a serious drawback, as the ore, together with the other dust always present in furnace gases, piles up so rapidly that it soon stops up all the passages for the heated gases. The Cahall boiler, from its construction, is freed entirely from this trouble, as the surfaces being prac- tically vertical, there is no chance for the accumulation of dirt of any kind on the heating surfaces. It all falls to the bottom part of the boiler, where ample provision is made for readily and easily removing it whenever occasion requires. ■z, s 2; S CAHALL WATER TUBE BOILER 20 Cahall Boilers for Utilizing Waste Heats For many years it has been a problem, not only in rolling mills but in many other industries, how best to utilize the waste heats from heating or puddling fur- naces. In many instances manufacturers have gone to the enormous expense of building elaborate regenerative furnaces of various types, which not only necessitate a very high first cost, but great expense for repairs, which also require considerable time to effect. In any plant where furnaces of any kind for heating or puddling are used, and where there is any steam power required, the ideal method for utilizing the heat from these gases is to make steam with it. We have a special design of boiler (cuts of which are shown) intended solely for the purpose of utilizing these waste heats. It is much cheaper to build a good reverberatory furnace and attach a boiler thereto, than it is to build a first-class regenerative furnace, and in most plants, especially in the iron and steel industry, sufficient steam power can be generated from waste heats to run the entire works, thereby not only saving the cost of the fuel now being burned under existing boilers, but saving the room occupied by those boilers and the wages of the firemen necessary to handle the coal and ashes. In general practice, the waste heat boiler applied over a heating or puddling furnace will deliver a horse power for each five pounds of coal fired in the furnace per hour, and with coal at §i a ton, a horse power of steam costs, with boilers direct fired, about $25 per annum. A heating furnace, therefore, consuming the equivalent of 600 pounds of coal an hour, will deliver steam from its waste heats aggregating 120 CAIIAT.L VERTICAL BOILER FUR WASTK HEATS CAHALL WATER TUBE BOILER 31 horse power, or a money value of about $3,000 per year, with coal at $1 per ton, delivered. This amount of saving will, each year, more than pay the entire cost of the boiler plant complete, ready for steam ; in fact, in the Pittsburgh district, where coal can be procured at the very low price of sixty cents per ton, delivered, we have several plants of these waste heat boilers running on which the saving on coal alone pays an annual dividend of from 115 to 140 per cent, on the first cost of the boiler plant complete. This is a very important subject, and one that requires careful consideration on the part of manufacturers having places wherein to make installations of this kind, and we would like very much to open correspond- ence and furnish drawings and estimates for installing these waste heat boilers in places where it is possible. FEDER.'\L STEEL CO.'S LORAIN! BLAST FURNACES, LORAIN,: OHIO 0,(1(111 H. I'. CAHALL VERTICAL BOILERS (A B J O B « H CA M I-' J 2; o h u IP. O >5 CAHALL WATER TUBE ROILER 33 Cahall Horizontal Boilers The illustrations given show the horizontal type of boiler manufactured by the Aultman & Taylor Machinery Co., of Mansfield, Ohio. Some time ago, finding that there were many locations where it was impossible, on account of lack of space, to install a vertical boiler, the Aultman & Taylor Machinery Co. decided to build a horizontal water tube boiler in addi- tion to their vertical. After thorough investigation they decided that the sectional header type had .shown the best results of any of the horizontal water tube boilers in the market, and they therefore adopted this type for their horizontal boiler. These boilers are built in sizes of from 125 horse power up to 850 horse power in single units. They also build what is known as the "double-decker" type of this same boiler. The boilers are built for working pressures of from 160 pounds to the square inch up to 500 pounds to the square inch. The factories of the Aultman & Taylor Machinery Co., at Mansfield, Ohio, are ample in size, are new, and equipped with the very latest tools and machinery. With the exception of the hydraulic and pneumatic plant, all the tools in the factory are direct electrically driven. The factory has an annual capacity of 400,000 horse power of Cahall Vertical Boilers and 200,000 horse power of Cahall Horizontal Boilers with the present facilities. Going into specific detail as to the manufacture of these boilers, we will begin with the steam drums. These are made of best open hearth flange steel, the heads for the drums being of the same material, hydraulically flanged. AH the sheets are beveled on FR(.)N'r VIKW OF Sr,ll IIP. CAHALL Hi IRIZl iX'i'AL I'.OII.ER CAHALL WATl'.R TUBK liOILER 35 the edges, bent into shape, and the rivet holes drilled after bending. This insures absolutely round holes without crystallization and allows calking of all seams, both inside and out. In boilers the working pressure of which is not to exceed i6o pounds to the square inch, the longitudinal seams in the drums are double riveted. In the higher pressure boilers, that is, from i6o up to 500 pounds, all horizontal seams are butt and double strapped joints with six rows of rivets. This makes the very finest possible joint, and when made with the care that is always exercised in our factories, is really a piece of fine art in boiler manufacture. Each drum is provided at both ends with the Cahall patent swinging man-head. This device, although very simple, is something of great importance. Engineers who have been annoyed with the laborious and tedious practice of taking man-heads out of boilers and lifting their heavy weight to a place of security, and then going through the annoyance of putting them back in their places again after the work in the boiler is finished, will appreciate fully the device which is furnished with these boilers. By simply loosening the nuts on this man-head, a slight push swings the head in as though it were a door, and it fits back in place against the drum, without occupying any appreciable amount of room, and when the time arrives to again close it, it is pulled back to its place Being hinged, as it is, the seats come together in exactly the same place every time, and the joint being made tight once is tight for all time, less than one minute being required to open the man-head and close it perfectly tight. The flanges on the steam drums for the steam and safety valve openings are all drop forged, from flanged steel plates. It will be noticed from the rear view of the boiler in the accompanying illustration, that each section of (a M o 'J. u. o o 5 a o >< Q < W CAHALL WATER TUBE BOILER 37 tubes is connected by nipples to cross-boxes, or saddles, on the steam drums. In all other boilers of this type made at the present time, these cross-boxes are man- ufactured either of flanged steel plates or cast iron. Both of these are improper. If made of cast iron, it is impossible to have the curvature of the box conform exactly to the curvature of the drum, and when they are riveted in place either one of three things must occur : (i) The sheets in the drums are distorted, (2) the cast iron is cracked from the pressure, or (3) a leaky joint is made. The leaky joint is the most frequent result. When the manufacturers find this they generally attempt to calk up the space with various metals, lead or babbitt metal having been u.sed in many cases, with the result that might be expected. After the boilers have been tested and accepted, the metal melts out and serious and irreparable leaks develop. The flanged cross-boxes are wrong for the reason that they are made of a flat sheet, which through successive heatings and applica- tions of hydraulic pressure is bent around sharp corners, resulting in a great pull or strain or stretch on these corners, which frequently reduces the thickness of the metal in places to the danger point. Moreover, at the ends of the cross-boxes, where the outside nipples go in, the recess inside the cross-box is so shallow that it is impossible to remove a nipple after the boilers are once erected without tearing down a portion of the brick work to do it. In the Caliall Horizontal Boiler these cross-boxes are made from open hearth steel, which is melted and run into molds, making what we have termed "flowed" steel. This steel, after cooling and annealing, presents all the chemical and physical properties of regular boiler plate steel, physical tests on a large number of coupons from these forms showing an elonf^ation of over 25 per cent., a reduction in area of over 50 per cent., with a tensile strength of over 60,000 o X X < Q CAHALL WATER TUBE BOILER 39 pounds to the square inch. Manufacturing the cross- boxes under this process allows any thickness of metal desired at all points in the cross-box where it is most desirable, and, moreover, permits making sufficient depth in the cross-box to make renewals or repairs of connecting nipples without interfering with any other portion of the boiler. This is a feature that is bound to become recognized as one of great value within a few years, when the troubles that are certain to arise from the use of forged steel cross-boxes and headers become more generally known. The steam drums in their entirety are made of the very best of materials, and the workmanship is exact, everything being done to templates, and all parts fitting to a hair's breadth before the drums are even tested. As will be seen from the illustrations, the headers or manifolds into which the tubes are expanded are of the standard sinuous type. These headers are made of a special mix of cast iron. The Aultman & Taylor Machinery Co. have been building steam engines and other machinery requiring very intricate and deli- cate castings for nearly thirty years, and have a most thorough knowledge of the best mixes of iron to accom- plish given results. To secure the best effects with these headers the mix must be a tough, close-grained iron, and the mix that we use for this purpose shows a tensile strength nearly 25 per cent, higher than that used heretofore in the manufacture of headers of this type, as shown by actual hydraulic stress applied in numerous instances. AVe also make these headers about 25 pounds heavier that has been customary with other manufacturers of these boilers in the past, and distribute this additional weight almost entirely in the form of fillets where sharp corners have heretofore been allowed. There are no sharp corners permitted in the headers of our manufacture, every corner being filled out to a KliAl-; \-IE\V OF :;r,ll I-l. p. CAHALL IK iKIZON'I'AL KOlUiR SUSPENDED READY FuR PRICK WORK CAHALL WATER TUBE BOILER 4I perfect curve by the use of these fillets. The result is, that while cast iron headers as heretofore made will break at an applied pressure of from 1,400 to 1,600 pounds to the square inch in nearly all cases, we repeatedly subject those made at our works to a pressure of 2,000 pounds to the square inch without any sign of rupture. The holes in these headers for the reception of the tubes, and into which the tubes are expanded, have in other makes of sectional header boilers been generally left rough as they come from the sand. As it is impossible to get a perfect seat in this way, leaky joints have been very frequent. We have designed a special tool for reaming all these holes to an absolutely perfect seat, preventing the possibility of this leakage ever occurring. The seats on the opposite side of the manifold covered by the hand-hole caps, for access to the tubes after the boiler is erected, are cut down and milled to a perfect face and the caps which fit over these are also milled and smooth finished, so that when they are put in position they make a steam and water tight joint without the inter- vention of packing of any kind. The hand-hole guards which go inside these hand-hole plates, to which the bolt for fastening the hand-hole plates in position is fastened, are made of drop-forged steel and are elliptical in form, so that they cover almost entirely the inside of the hand-hole. This is done as a safeguard, so that in case a bolt fastening the hand-hole plate in position should break from any cause, there can be no sudden rush of steam or water through the hand-hole, which has frequently occurred with considerable damage to men and property. The bolts used for fastening these hand-hole caps in place are of the very best iron, 1 li inches in thickness. It can be seen from the side view of the boiler that it stands on wrought iron supports and cross beams, independent of the brickwork, so that the entire structure is free to contract and expand without 0-9 Bf 3P> m a! H O M J <: z o fj 2 o I ■=■:.,(. . , ^ ■•?<». .K >^ .»M-"'*i£-" BUCHANAN & LYALL, BROOKTA'N, N. Y. nun H. P, CAHALL HORIZONTAL BOILERS CAHALL WATER TUBE BOILER 49 their places again after the work in the boiler is finished, will appreciate fully the device which is shown in the cuts on page 47. By simply loosening the nuts on this man-head, a slight push swings the head in as though it were a door, and it fits back in place against the drum without occupying any appreciable amount of room, and when the time arrives to again close it, it is pulled back to its place. Being hinged, the seats come together in exactly the same place every time, and the joint being made tight once is tight for all time; less than one minute is required to open the man-head and close it again perfectly tight. BORINGS A\l) TURNINGS FROM "FLOWKD" STKEL H •J, O m W < o < K o Q Z -^ '- o S w P < W X Q K K < CAHALL WATER TUBE BOILER S3 the plain fiat grate, or hand firing, of from lo to 15 per cent., and about three-fourths of the labor expense is saved in a steam plant thus equipped, the stokers be- ing automatic. The fact that the majority of the lead- ing mill owners throughout the country are having all their modern plants equipped with this device, and in many cases are having their old plants modern- ized through tearing out the old flat grates and sub- stituting therefor the chain grate stoker, should, we think, speak volumes for the worth of the device. IIANSFIULD CHAIX GRATE STOKKR Sliowing how it can be withdrawn from under bi.'iler XEW YORK & STATEN ISLAND ELECTRIC CO., STATEN ISLAND, N. Y, 2,450 H. P. CAHALL HORIZONTAL BOILERS CAHALL WATER TUBE BOILER 55 The Advantages of the Cahall Boiler 1 . Absolute safety from disastrous explosions, and the total absence of all cast metal in its construction. 2. Accessibility for cleaning, examination and repairs. 3. vSpecial adaptability to situations where feed water is impure. 4. liigh pressure, every boiler being designed to carry a constant working pressure of 150 pounds. 5. Perfect circulation, tending toward preserving uniformity in the temperature in all parts of the boiler, thus doing away Avith the excessive strains due to the sudden heating and cooling of metals and the consequent loosening of parts. 6. The marked ease with which a tube may be re- moved and replaced. This feature is in striking con- trast to the horizontal type, in which, in case a tube ruptures and gets out of shape, it frequently cannot be withdrawn through the hole in the tube sheet, but must be taken out by cutting away, on the side, above or below, as the case may be, as many tubes as prevent its removal. 7. Economy in fuel, OAving to the judicious arrange- ment of baffle tiling, by which the largest proportion of heat units contained in the gases are utilized in the most efficient manner, and the gases leave the boiler at a low temperature ; owing also to the provisions that have been made for keeping both the inner and outer heating surfaces clean and free from accumu- lation of scale on the one hand, and soot and ashes on the other. This also tends to promote the durability and prolong the life of the boiler, as the danger of tubes w o r J O < ^ o 5 K CAHALL WATER TUBE BOILER 57 burning out is reduced to a minimum when they are kept clean both inside and out. 8. Economy in maintenance, due to its extreme simplicity, the ease with which it can be cleaned, and the readiness with which defective tubes may be removed and new ones inserted. MANSFIELD CHAIN GRATE STOKER WITHDRAWN FROM BOILER SHOWING FIRE o w Q B m t^ o a m Q < H ffi J ■< O o s^ o .J d o 2 E o W P5 P P o M 2 CAHAI.I, WATIiR TUUE UOILER rn Tests of Cahall Boilers The Armstrong Cork Company, of Pittsburgh, Pa., having in use a 250 horse power Cahall boiler run- ning in connection with other water tube boilers of a very well known make, and wishing to determine the exact performance of their Cahall boiler, from time to time made, through their own engineers, tests for efficiency and capacity. The results they obtained from their Cahall boiler in these tests appeared to them too high, being so very much better than anything they had ever been able to secure from the other water tube boilers in use at their works, so arrangements were made to have tests conducted to check theirs, by well known engineers from other cities. There have been in all nine tests made on this boiler, and we present them herewith. It will be noticed on test No. 7, the boiler being run at 60 per cent, above its rating, showed an efficiency of over 71 per cent., while on test No. 6, the boiler being run only about 3 per cent, above its rating, showed an efficiency of nearly 86 per cent., while on test No. 2, with the boiler 1 1 per cent, above rating, the efficiency is nearly 82 per cent. Test No. 5, running 32 per cent, above rating, showed an efficiency of 79 per cent. The nine tests made by different people at different times, with coals that vary in their general composition, extending over a period of eight months, during which time there was never a tube in the boiler scraped, show a wonderfully uniform series of results ; the efficiency bearing almost a direct fixed ratio to the capacity in every test ; the minimum efficiency being about 70 per cent, with the boiler driveh at double its rating, the maximum over 85 per cent, with the boiler at about its normal horse power. SUMMARY OF NINE TESTS MADE ON ONE 250 H. P. CAHALL BOILER AT FACTORY OF THE ARMSTRONG CORK CO., PITTSBURGH, PA. 1 ' 2 ; 3 ' '>: '^^ ^^ , ^""'- By Armstrong By Armstronf? C.I,, ot (_hi- Cork Co. Cork Co. n'icoNoMy 1 (Economy.) (Capacity.) Date of test Duration of test . No. of boilers. . . . Average Pressure of Steam in Boiler by Gauge. Average Temperatures : of feed water enterin,^' builer Oi steam in b, liler .hours ....lbs Ian. n, ISOli !) 1 .30. ■? 3a6 Apr. 22, 181113 6S 333.9 Fuel (kind of eoal) ^ Cost per tfin of 3,000 pounds delivered Calorifie power by calorimeter 11. T. I'. Total quantity consumed lbs. Total ash, clinkers and unl:)urned eoal lbs. Proportion of ash, &c., to coal ]^cr cent. Total c.03 24.64 .3.505 .3318 Apr. 23, 1890 9 1 65 343.2 Nut and slack .Summer Hill .W1.95 12,430.4 14,466 1,211 8.3 13,355 1,6073 1,473 4.5.92 43.08 .618 ..566 Water— iVnrount apiiarenLl\- ex'aporated I'^actor of e\'aporation Equi\-alent e\'aporation into dr\- sic at 313» F ; 90,112.75 Economic Evaporation — per pound of eoal : Water aetualU- e\-apoiaLed Dis. Equivalelrt from and at 213^ 1'' Iljs. Per pound of combustible water- actually e\'ap- orated lbs. Equi\-alenl from and at 312" V lbs. Evaporation per Hour: Water actually evaporated II is. Equivalent fro:n and at 312^ 1' I Ijs. Per square foot heatiuK^ surface — water aetiudl\- evaporatcd lbs. Equivalent from and at 213^' \^ lbs. Per square foot ^^rate suid'aee — water .iclualh- evap- orated Ills. Equi\'alent fronr and at 313'-' 1' lbs. Efficiency : Percentage of total calorific power utili/.ed, or efTi- eiency . . ,■ ]-)er cent. Water evaporated per ^l.oo worth of fuel lbs. Cost of evaporatmg 1,000 lbs. of water cents. Coal consumed per horse power pei- h.mr lbs Cr.st of same eenls 1.3IH 1.1881 II9,;573 86,471.69 8.648 10.533 8.87 10.54 9. 384 11.43 9.37 11.14 10,012.5 12,195.3 S.0R4.11 9,607.96 3.85 4.69 3.19 3.7 380.07 34S.43 230.97 374.51 130,503 1.1943 8.33 9.95 9.01 10.86 13,.: 15,t >.S8 1.74 5.15 6.15 3,S3.55 456.87 77.7 81 97 77.39 9,o:iK :;2, 186.1 30,895 .0.52 .1145 .a47f 3.37 3.3.S 3.46 .1)018 .0015 .OOIC Horse Power : Actually (Icvelnped (in Ixisis uf 34i_, lbs, waLcr evap- orated per hiiur from and at '^13'^ F Commercial ratiny: Proportion capacit}' de\-tlf coal by the ' ' Bomb Calorimeter" 12,854 B. T. U. 48 Efficiency of boiler j^erforraance in percentage of the theoretical value of the coal as above . 85.862 per cent. 49 Cost of coal per ton (2,000 lbs. ) . . . 95 cents 50 Possible evaporation for one lb. of coal, actual conditions ....... 11. 2214 lbs. 5orf Actual evaporatiim imder working conditions (see item 31) . . . . . . . 9.6347 lbs. 51 Percentage of possible evaporation realized under actual conditions ...... 85.862 per cent. 52 Heat units in one ton of coal .... 25,708,000 B. T. U. 53 Heat luiits required to make one ton of water into steam, actual conditions . . . 2,291,000 B. T. U. 54 Possible tons of water into steam with a ton of dry coal ........ II. 2214 tons 55 Cost of 2,000 lbs. of water into steam, actual con- ditions ....... 8.4661 cents 56 Pounds of water into steam for one cent, actual conditions ....... 236.24 lbs. 57 Horse powers of 34.488 lbs. of water per hour at and from 212'' F., A. S. M. E. code or its ecjuivalent, 30 lbs., from 100° F., to 70 lbs. steam guage pressure, for one cent . . 6.8503 H. P. 58 Cost of one horse power of steam one hour, in fraction of a cent .146 B Q Pi O CAHALL WATER TUIiE BOILER 69 59 Heat units for one cent ..... 60 Theoretical loss of possible heat units, all sources 270,620 B. T U. 14. 138 per cent. (Signed) TiioM.\s Pkay, Jk. (Case 3666 ) Cahall Boiler, 250 Horse Power (maker's rating), with Hawley Down Draft Furnace, at Armstrong Cork Co.'s Works, Twenty-fourth and Railroad Streets, Pittsburgh 1 Date of trial, May 5, 1896. 2 Duration, S A. m. to 5 !■. m. (no noon hour) 9 hours Dimensions and Proportions 3 Grate surface, 5 ft. long by 7 ft. wide ... 35 s(|. ft, 4 Water heating surface ..... 2,494 si| ft. 5 Superheating surface ...... i4{) sq, ft. 6 Ratio of water heating surface to i of grate surlace 71.257 Average Pressures 7 Steam pressure in boiler by gauge ya Error of water column .... ■;/> Correct steam gauge pressure 8 Absolute pressure per sq. in. • 9 Barometer (U. S. Signal Service) <)// Atmospheric pressure in lbs. per sq. in. 10 Force of draft in inches of water 100.5S lbs. 12,592 lbs. 87,9X8 lbs. I02.6:j9 lbs. 29,95 ill. 14. 71 1 lbs. .6324 in. Average Temperatures n Of external air 78^ F. 12 Of fire room ........ ijG" F. 13 Of the steam at 102.699 Ib.s. per square inch . . 329.5° F. 14 Of escaping gases ....... 477.772° F. 15 Of the feed water 6S.2° F. Fuel 16 Total amount of coal from the pile 17 Moisture in the coal 17a Moisture in the coal 12,893 lbs. 2 per cent. 257.86 lbs. u ■fi 'A O ^ f/: ^ o 5 o '— ' o ^ ►J '-' < X < u 0,' K CAHALL WATER TUBE BOILER 71 18 Dry coal ig Ashes and cinders 19a Ashes and cinders 19^ Pounds of moisture igc Total losses in coal 20 Pounds of combustible 21 Dry coal consumed per hour 22 Combustible consumed per hour ashes and cinders from all causes 12,635. 14 lbs. 1,614 lbs. 12.774 per cent. 1,871.86 14.51SS per cent. 11,021.14 I 403.9 lbs. 1,224.59 lbs. Results of Calorimetric Tests 23 Quality of the steam, dry steam being taken as unity 24 Moisture in the steam ...... 25 Number of degrees of superheat .... 25a Percentage of superheat ...... 26 Total quantity of water pumped into the boiler and apparently evaporated ..... 27 Water actually evaporated, corrected for the quality of the steam ...... 28 Equivalent water evaporated into dry steam at and from 212° F. ...... . 28rf Factor of evaporation ...... 29 Equivalent British Thermal Units from the fuel 30 Equivalent water evaporated into dry steam at and from 212° F., per hour ..... 1. 01443 0. 000000 26 499 1.443 107,234 lbs. 108,780 lbs. 129, 130 lbs. 1 . 1 87 1 I4S,030, ,*■■ — -"■ 'f'^- CAHALL WATER TUBE BOILER 73 Rate of Evaporation 3g Water evaporated at and from 212° F. per sq. ft. of heating surface each hour .... 5.88691135. 39a Water evaporated at and from 212° F. per sq. ft. of grate surface each hour .... 409.94 lbs. Commercial Evaporation 43 Horse power of boiler, per American Society of Mechanical Engineers' code, on basis of 30 lbs. of water per hour evaporated from tempera- ture of 100° F. into steam of 70 lbs. gauge pres- sure = 34.5 lbs., from and at 212° F. . . 416.055 44 Horse power of boiler (builder's rating), 10 sq. ft. of heating surface per horse power . . . 250 H. P. 45 Excess of maker's rating in the performance of the boiler 66.422 per cent. 45a Square feet of heating surface for one horse power 5.9945 451^ Square feet of grate surface for one hor.se power . .084318 Efficiency 46 Heat units accounted for in the water for one lb. of dry coal 9,869 B. T. U. 47 Heat units in one lb. of coal by the calorimeter (3 tests) 13,850 B. T. U. 48 Efficiency of boiler performance in percentage of theoretical value of the coal as above . . 71.259 per cent. 49 Cost of coal per ton (2,000 lbs. ) .... 95 cents 50 Possible evaporation per lb. of coal, actual conditions 12.0S2 lbs. 50a Actual evaporation under working conditions (see item 31) ....... 8. 6094 lbs. 51 Percentage of possible evaporation realized under actual conditions . . . . . . 71.259 52 Heat units in one ton of coal (2,000 lbs.) . 27,700,000 B.T.U. 53 Heat units required to make one ton of water into steam, actual conditions .... 2,292,740 B.T.U. 54 Possible weight of water into steam with a ton of dry coal ....... 12.0S2 tons 55 Cost of 2,000 lbs. of water into steam . . . 7.863+ cents 56 Pounds of water into steam for one cent . . 254.35 lbs. 57 Horse power of 34.4S8 lbs. of water per hour at and from 212° F., American Society Mechanical Engineers' code or its equivalent, 30 lbs, from 100" F. to 70 lbs. steam gauge pressure for one cent 7.375s H. P. BULLOCK ELECTRIC MANUFACTURING Co., CINCINNATI, OHIO 500 H. P. CAHALL VERTICAL BOILERS AND CHAIN GRATE STOKERS CAHAl.I, WATER TUHl', 11(111. ER 75 58 Cost of one horse power of steam mie hour in frac- tion of one cent ...... .136 59 Heat units for one cent ...... 291,582 B. T. U. 60 Theoretical loss of possible heat, all sources . 28.741 percent. The Bomb Calorimetric results were done for me at Cornell Univer- sity, and received on May 26, at which time I was hundreds of miles away on similar work; could not finish the computations sooner. Boston, May 14, 1896 (Signed) Thomas Pray, Jr. ARMSTRONG CORK CO., PITTSBURGH, PA. 500 H. P. CAHALL VERTICAL BOILERS ^ o 5 ^ t; _:= CAHALL WATER TUBE I!U1LER 7 7 Final Report and Results of Tests made at Armstrong Cork Company, Pittsburgh, Pa., May 4 and 5, 1 896 (Cases Nos. 3665 and 3666) Full Report Herewith, as Rendered This final report deals only with the chemical analyses of coal used on days as above, and the results as computed by me in my usual practice, items 46 to 60, inclusive (these items are computed strictly with the code of the A. S. M. E., but are not recognized in that code as it now stands on the Transactions of that Society). Chemical analyses were made at the Cornell University for me, and the determination of the theo- retical British Heat Units in a pound of coal was also made at Cornell. In the computation of the B. T. U. of coal with so high a percentage of volatile, the most reliable formulas are sadly at fault, hence I have adopted the "Bomb Calorimeter" determination, in place of some of the so-called utterly unreliable " Coal Calorimeters," and in such tests prefer to employ entirely disinterested persons to do this work, than to do it myself, although familiar with the work. The coal used was sampled from each two hundred pounds and a final sample drawn from this amount and put into a tin can, soldered up in the yard, and sent away to the chemist each day. The coal was shoveled off the cars in the yard of the Armstrong Co., 'msi^ AIIERICAX FILE CO., PAWTUCKET, R. I. CAHALL WATER TUBE l;OILER 79 at various times each day, or as the men had the time to do it. The test of the Cahall boiler for capacity is one of the best I have seen, in over four thousand boilers already tested, without one exception ; a boiler rated by builders as 250 horse power, under American Society of Mechanical Engineers' code, of 34.4876 pounds of water at and from 212 degrees Fahrenheit, or its equivalent, which calls for the use of 33,305 B. T. U. an hour, whatever the pressure and temperature may be under actual conditions. That this boiler did for nine hours easily, and could have done for nine days, one hundred and sixty-sLv and four Imndred and tiventy-tiuo one tlwnsandths per cent, of that rating, or 416.055 horse powers, with an efficiency of 10.22 pounds of water at and from 212 degrees Fahrenheit with one pound of dry coal, and the fires not managed at their best, is certainly not other than an extraordinary result ; no sort of change was made from its usual every day conditions ; it was not, as in some similar cases, done with a grate surface cut down, or some other factor changed, but it was an every day test, by the regular fireman of the concern who owned the boiler, and this man ran it to suit himself (it was not a particle of use to suggest to him), and under these con- ditions, 71.259 per cent, of the possible heat units by laboratory test were accounted for in the water and steam ; the whole day had a superheat in the steam amounting to 1.443 per cent, or 26.499 degrees Fahren- heit above temperature due to pressure. I regret not being able to send this final report sooner, but it requires time to do properly the chemical analyses of coal, and in these cases more than one deter- mination of each has been made ; the variation between any two is almost immaterial, but the average of three in each case is considered as final. o < o t- u o O J to J D ^ K ;^ C y: CAHALL WATER lUBE EOILER 8i When the analyses came, I was away, and now improve first day possible to forward you, and am cer- tain that the results will interest steam users who are looking for facts. All of which is respectfully submitted. Thomas Prav, Jr. Boston, June 2, i< 95 Milk Street, Room 71. BOILER HOUSE, LANCASTER MILLS, CLINTON, MASS. 2V50 H. P. CAHALL VERTICAL BOILERS X < < CAHALL WATER TUBE BOILER 83 Test Made on a Cahall Waste Heat Boiler at the Republic Iron Works, Pittsburgh, Pa., by the Pitts- burgh Testing Laboratory, June 2 and 3, i 893 Duration of Test. — The test was run from 4 p.m. on June 2 to 3 a.m. on June 3(11 hours), which was from charge to charge of furnace. During the last half hour, while they were making new bottoms, no gas was used. Boiler. — The boiler tested was a Cahall Patent Vertical Water Tube Boiler, having seventy-two 4-inch and six 5-inch tubes, on 1332.4 square feet of heating surface. Diameter of steam drum, 60 inches; height, 80 inches; diameter of mud drum, 78 inches; height, 42 inches; diameter of up-take through mud drum, 38 inches. Rated by the makers as 125 horse power. The boiler was connected with a single re-heating furnace, and used the waste gases as fuel. During the test seven heats were made, and the total weight of the finished iron was 25,300 pounds, being rather more than the amount finished by other furnaces in many works running eight heats. Fuel. — The fuel used by the re-heating furnace was natural gas. The following is an analysis of same : Carbon dioxide 0.7 per cent. Illuminants . • o. 2 " " O.xygen . . . . . . . . o. i " " Carbon monoxide . . . . . 0.5 " ■' Hydrogen None. Marsh gas 64-5 per cent. Nitrogen 34-o " 1 00.0 per cent. ST. LAWRENCE SUGAR REFINING CO., MONTREAL, CANADA USING 1,500 H. P. CAHALL HORIZONTAL BOILERS 71 62 per cent. 5 15 92 .. 11 51 " 10 30 50 per lOO .00 cent CAHAl.L WATER TUBE UOILER 85 The large amount of free nitrogen in the gas would account for its rather low efficiency. The heat units per cubic foot of this gas were 682.36 B. T. U. The following is the analysis of the coal on which this boiler had been previously run and tested : Carbon ....... Hydrogen ...... Sulphur ...... Oxygen and nitrogen Ash Moisture The number of heat units per pound of coal was 13,617.7 B. T. U. Or, theoretically, 20 cubic feet of natural gas used was equal to one pound of this coal, or 40,000 cubic feet equal to one ton. Two analyses were inade, which checked with each other, showing that the gas was of the above composition. The method of firing the furnace was through a manifold, which had seven fingers J^^-inch in diameter, alternating with seven fingers one inch in diameter. The pressure was measured by water gauge, the aver- age pressure being 3.13 inches of water. The amount of gas used was 101,515 cubic feet. Water. — The water used was measured in two barrels, first barrel being filled until the tell-tale ceased dripping, when it was emptied into a second barrel and then fed into the boiler with a Mack In- jector. The weight of water by scale and by this method we compared, and found results to agree within less than a pound. Injector used steam from boiler tested. The total water evaporation was 50,700 pounds. At the start of the test, the height of the water in the water gauge was noted by a band around the gauge. At the close of the test the water was brought to this mark. Analysis made of the gas taken SICILIAN ASPHALT PAVING CO., NEW YORK CITY 300 H. P. CAHALL VERTICAL BOILERS CAHALL WATER TUBE BOILER 87 from the stack during the test showed the following results : Carbon dioxide . . . . . 5, 90 per cent. Carbon monoxide ...... None Oxygen ....... 5,30 per cent. Nitrogen, j Sulphur dioxide, |- . . . . 8S.80 " " Aqueous vapor, ) 100.00 per cent. Steam Pressure. — The steam pressure at the start was 106^ pounds; at the close it was 105 pounds; the average pressure being 104.9 pounds. Calorimeter Tests. — Calorimeter tests were made at intervals through the test, showing, as an average, that the steam was superheated to 73.8 degrees Fahrenheit. The steam for the calorimeter tests was taken from the main steam pipe, at a distance of about eight feet from the boiler. The pipes were not lagged. When the steam was allowed to blow into the air, no conden- sation was observed for a distance of six feet, clearly showing that the steam was superheated to a high degree. The calorimeter used was an ordinary barrel calorimeter ; the weight of condensing water being about 300 pounds, and the amount of steam condensed being from five to ten pounds. The scales were read within one-eighth of a pound. Corrections. — The barometer used was an aneroid, which was corrected by the Weather Bureau. Ther- mometers and steam gauge were all tested and corrected before the test. Observations. — Observations were taken every fifteen minutes during the eleven hours, and the average of these used in the results obtained. Attached are the complete results of the test. The results show that this boiler is equally adapted to the Mmt*w W. W. KIMBALL CO., PIANO AND ORGAN FACTORIES 435 H. P. CAHALL HORIZONTAL BOILERS CAHALL WATER TUBE BOILER 89 use of coal or gas. Probably a much better test would have been shown (although this one is in our minds very satisfactory indeed) if the natural gas used had contained a less percentage of free nitrogen, or the coal a less percentage of ash. From the rapidity with which this boiler made steam, and from the temperature of the gases in the stack, we think in this particular case the boiler could be of somewhat larger size for this furnace to utilize economically the waste gases. One of the most notable features abotit this boiler is the extremely small amount of room which it occupies, taking but little more room than an ordinar}^ stack. Consideringf the size, simplicity, low cost, its equal adapta- bility for coal or gas, and its economical steaming properties, it is without doubt the best boiler for its purposes which has come under our observation, and we recommend it cheerfully for all iron and steel works. It is interesting to note, in connection with this test, the results in tests by other parties. We know of but very few comparative tests which we have made of the consumption of gas to that of coal under the same boilers, with the conditions as nearly similar as possible. The only comparative tests we know of are those of the Engineers' Society of Western Pennsylvania, and the tests of the Allegheny County Light Company and the Allegheny Gas Works. The number of cubic feet of gas required to evap- orate one pound of water, from and at 212 degrees Fahrenheit, as found by tests at the Allegheny Gas Works, was 1.33, 1.37, i-39 and 1.78, and those of the Allegheny County Light Company, 1.43, 1.78 and 1.50. Our test showed that to evaporate one pound of water, from and at 212 degrees Fahrenheit, it took 1.686 feet of gas. It must be borne in mind that on these other tests the gas was burned directly under the boilers and had •a w l-J S5 O W P5 O , o w ^ ^^ CAHALL WATER TUBE KUILER 9I no other work to do, while in our test the gas first had to heat 2 5 , 300 pounds of iron, and that the gas itself had a much less theoretical calorific value. In a series of tests made by the Fuel Oas & Elec- trical Engineering Company, theoretically, it required nearly 1,000 cubic feet of gas to evaporate as much water as 55 pounds of coal, or 36,360 cubic feet of gas equal to one ton of coal. S. A. Ford, of The Edgar Thomson Steel Works, after his long series of well-known experiments, deter- mined that 1 ,000 cubic feet of gas was equivalent to 54.4 pounds of coal, or 36,760 cubic feet of gas equal to one ton of coal ; and in our own case, we obtained by analysis that 1,000 cubic feet of gas was equal to 50 pounds of coal, or 40,000 cubic feet of gas equal to one ton of coal. It is thus clear that the quality in this case is much below that commonly used elsewhere. Ffom the above it will be seen that this boiler, using the waste g'ases from a re-heating: furnace, is very nearly equiva- lent to the other boilers noted, which burned the g:as directly underneath them. This is no doubt due to the fact that they are not so well adapted to the use of gas as fuel as the Cahall boiler. This is only natural, as the best results are obtained with long tubular or return tubular boilers, for in case of short boilers there is too little space between the flues, and between the flues and top shell — that is, they get very little advantage from the waste gases ; and no doubt if a pyrometer test had been made of the escape gases in the tests noted above, a very high temperature would have been shown. Description of Boiler. — One 125 horse power Cahall Vertical Water Tube Boiler; diameter of steam drum, 60 inches; height, 80 inches; diameter of mud drum, 78 inches; height, 42 inches; diameter of up-take through mud drum, 38 inches; number and diameter of o m < Z O X z t«1 o o CAHALL WA'IER TUBE BOILER 93 flues, seventy-two 4-inch and six 5-inch. Duration of test, 1 1 hours. 29 4 Square feet of heating surface Kind of fuel used (analysis given) . Cubic feet of gas .... Cubic feet of gas per hour Average steam gauge pressure . Average steam absolute pressure . Average draft pressure, inches <]f water Average gas pressure, inches of water Average barometer .... Average temperature of feed water Average temperature of outside air Average temperature of boiler room Quality of steam, dry taken as unity (superheat) Pounds of water evaporated (actual conditions) . Pounds of water evaporated (actual conditions) jier hour Pounds of water evaporated (actual conditions) per 1,000 cu. ft. of gas ....... Pounds of water evaporated (actual CDuditions) per i cu. ft of gas . ........ Pounds of water evaporated from and at 212° F. per 1,000 cu. ft. of gas ........ Pounds of water evaporated fn>m and at 2 [2° F. per i cu. ft. of gas ........ Cu. ft. of gas required to evaporate i lb. of water (actual conditions) ......... Cu. ft. of gas required to evaporate i lb. of water frnm and .at 212° F. Pounds of water evaporated, actual conditions, per i lb. of combustible, by analysis, equivalent of gas Pounds of water evaporated, from and at 212'' F. , per i lb. of combustible, by analysis, equivalent of gas Pounds of water evaporated per sq. ft. heating surface per hour ... Horse power actually developed Hor.se power from and at 212° F Centennial Standard ... ... Rated Per cent above rated capacity, actual .... Per cent above rated capacity. Centennial .... Sq. ft. of heating surface per horse power, actual . Sq. ft. of heating surface per horse power, Centennial 1.332.4 Natural (las. 101.515 9,228.6 104.9 lbs. 119.34 lbs. 0.40 in. 3, 13 in. 14.43 lbs. 71.16° F. 86.6° F. 100.1° F. 73 S° F. 50,700 4,609. I 499.32 0.4993 592.79 0.593 2.002 1.686 9.989 11.859 3 46 153-64 182.41 158.6 125 22.91 26.88 8.67 8.40 O o »— I . 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X Cl l- pad JI3A9P -d -H 7 ;>; = ,^- L ■, ,-; ',: e- .-. i /,-:;- 3 ,^ ^-. 7- S S Jo "-'■■-■•'■ ' -^ .! -f -T _ .[.r; ci ci ■>iut;Tj-^^ -f : t : : : : : : i i ! : : : : : : : 0^ u ■^■■-. ■^^-.-■'-■r- y. : bi r- : ^ : : ;tO ' -. i' : 5 ■ W y: v; X ir r z X x S: x X X x x X X X crj X Oct. 1 June 2-3 April 21' Mav 11 Aug. ii; Ian. 1 Jan. 14 Jan. IC Ian. 31 ■April 22 April 23 May 4 May r, June 11 [une 24 Aug. 11 Aug. 12 Sept. 311 Dec. 31 Q - ■ ■ - ^ ■ ■ ■ _; . _ ■ ■ _ ^ ■ • s • ■ o ■ : ■ A ■ £ • J : c?f : :2-Si; -Su-S 5:2 -S g Mansfield, ks, Pittsbu aron. Pa. , tonia, O. . . , Wyando ., Pittsbur New Cast ., Pittsbur Rankin St .., Pittsbur Ld., Pittsb Lockport, ., Pittsbur oal and Ir 5 H ^ Itman & Taylor, public Irun Wor aron Iron Co., SI em Iron Co., Lee chigan Alkali Co mstrong Cork C< worth Paper Co. mstrong Cork Cc rrie Furnace Co. mstrong Cork C' Tos & Laughlins, aders Paper Co., mstrong Cork C< ila. & Reading C Branchdale, Pa. rrimac Mfg. Co., hi ., Inc., Dki:x1'.i. Bcilmnc, Pnn.Ai)F;i,piiiA, Pa., January 21, 1S97 Pctin Steel Castiiii^ &-= Machine Co., Chester, l\t. Ge.mtlf;men; We have information that certain parties are claiming to be able to furnish — in fact, ofTer to furnish with their boilers — headers and other parts of ' ' iiowed " steel. As "flowed" steel is of a special mixture and our property, we would ask if you have ever furnished or are now furnishing "flowed" steel headers to any party or parties other than ourselves ? An early reply will oblige. Yours truly, (Signed) Thayer & Co., Inc. Office of Penn Steel Casting & Machine Co. Chester, Pa., January 21, 1S97 Messrs. Thayer &- Co., Inc., Dre.xel Building, Philadelphia Gentlemen: Referring to your inquiry of even date, we beg to state that we consider the special mixture for flowed steel we are making S5 z O 'J: o o: o 2 CAHALL WATER TUBE BOILER 99 for you your property, of which you have the sole right, and that we never have nor never will furnish flowed steel to any one but yourselves, unless authorized by you. Neither will we give to any one any informa- tion as to the formula mixture of which this special mixture is made. Yours respectfullv, Pk.NX S'lKEL C.\STIN(; & JL\(H1NE CO. (.Signed) Fkkd. B.vldt, Manager. "FLOWED" STEEL HEADER Hammered flat at one end and doubled back on itself without cracking m^-^m^^ 7i^ <.^^ T^^ aatSS^^iH^ HUDSON ELECTRIC LIGHT CO., HOBOKEN, N. J. 5U0 H. P. CAHALL VERTICAL BOILERS CAHAI.L W ATKR TUliE BOILER Vertical Headers for Cahall Horizontal Boilers The only object in using a header of this type is to economize space where a horizontal type of boiler is used. A header of this design enables us to install the series of headers at right angles to the steam and water drums overhead, instead of inclining them. Many points of advantage have been claimed by competitors of ours for this vertical type of header, nearly all of which are purely theoretical and are "selling points" mainly. The only valid advantage that can be claimed for this construction under any circumstances is the difference in room occupied, which amounts to about two feet in length for a 250 horse power boiler. .,t#r/4?>^- VERTICAL HEADER <; to g Pi ^ o O m p 5