This consists, in its most simple form, of a steam nozzle, the end of which extends somewhat into the second nozzle, called the combining or mixing nozzle; this connects with, or rather terminates in, a third nozzle or tube, termed “the forcer.” At the end of the combining tube, and before entering the forcer, is an opening connecting the interior of the nozzle at this point with the surrounding space. This space is connected with the outside air through a check valve, opening outward in the automatic injectors, and by a valve termed the overflow valve. The injector nozzles are tubes, with ends trumpet mouthed to receive and deliver the fluids with the least possible loss by friction and eddies. As a thermodynamical machine, the injector is nearly perfect, since all the heat received by it is returned to the boiler, except a very small part which is lost by radiation; consequently its thermal efficiency should be in every case nearly 100 per cent. Note.—The operation of the injector is based on the fact, first demonstrated by Giffard, that the motion imparted by a jet of steam to a surrounding column of water is sufficient to force it into the boiler from which the steam was taken, and, indeed, into a boiler working at a higher pressure. The steam escaping from under pressure has, in fact, a much higher velocity than water would have under the same pressure and condition. The rate of speed at which steam travels—taking it at an average boiler pressure of sixty pounds—when discharged into the atmosphere, is about 1,700 feet per second. When discharged with the full velocity developed by the boiler pressure through a pipe, say an inch in diameter, the steam encounters the water in the combining chamber. It is immediately condensed and its bulk will be reduced say 1,000 times, but its velocity remains practically undiminished. Uniting with the body of water in the combining tube, it imparts to it a large share of its speed, and the body of water thus set in motion, operating against a comparatively small area of boiler pressure, is able to overcome it and flow into the boiler. The weight of the water to which steam imparts its velocity gives it a momentum that is greater in the small area in which its force is exerted than the boiler pressure, although its force has actually been derived from the boiler pressure itself. Fig. 513.—See page 252. Fig. 514.—See page 251. All injectors are similar in their operation. They are designed to bring a jet of live steam from the boiler in contact with a jet of water so as to cause it to flow continuously in the direction taken by the steam, the velocity of which it in part assumes, back into the boiler and against its own pressure. There are three distinct types of live steam injectors, the “simple fixed nozzle,” the “adjustable nozzle,” and the “double.” The first has one steam and one water nozzle which are fixed in position but are so proportioned as to yield good results. There is a steam pressure for every instrument of this type at which it will give a maximum delivery, greater than the maximum delivery for any other steam pressure either higher or lower. The second type has but one set of nozzles, but they can be so adjusted relative to each other as to produce the best results throughout a long range of action; that is to say, it so adjusts itself that its maximum delivery continually increases with the increase of steam pressure. The third type, double injectors, are those in which the delivery from one injector is made the supply of a second, and they will handle water at a somewhat higher temperature than single ones with fixed nozzles. The double injector makes use of two sets of nozzles, the “lifter” and “forcer.” The lifter draws the water from the reservoir and delivers it to the forcer, which sends it into the boiler. All double injectors have fixed nozzles. The action of the injector is as follows: Steam being turned on, it rushes with great velocity through the steam nozzle into and through the combining tube. This action causes air to flow from the suction pipe, which is connected to the combining tube, with the result that more or less vacuum is formed, thus inducing a flow of water. Note.—The motive force of the injector is found in the heat received from the steam. The steam is condensed and surrenders its latent heat and some of its sensible heat. The energy so given up by each pound of steam amounts to about 900 thermal units, each of which is equivalent to a mechanical force of 778 foot pounds. This would be sufficient to raise a great many pounds of water against a very great pressure could it be so applied, but a large portion of it is used simply to heat the water raised by the injector. The above explanation will apply to every injector in the market, but ingenious modifications of the principles of construction have been devised in order to meet a variety of requirements. Fig. 515.—See page 252. Fig. 516.—See page 252. After the water commences to flow into the injector it receives motion from the jet of steam; it absorbs heat from the steam and finally condenses it, and thereafter moves on through the forcer tube simply as a stream of water, at a low velocity compared with that of the steam. At the beginning of the forcer tube, it is subjected only to atmospheric pressure, but from this point the pressure increases and the water moves forward under a diminished velocity. That the condensation of the steam is necessary to complete the process will be evident, for if the steam were not condensed in the combining chamber, it would remain a light elastic body and, though moving at high speed, would have a low degree of energy. Some injectors are given special names by their makers, such as ejectors and inspirators, but the term injectors is the general name covering the principle upon which all these devices act. The exhaust steam injector is a type different from any of the above-named, in that it uses the exhaust steam from a non-condensing engine. Exhaust steam represents fourteen and seven-tenths (14.7) pounds of work, and when the steam entering the injector is condensed the water is forced into the boiler upon the same general principle as in all injectors. The injector can be, and frequently is, used as a pump to raise water from one level to another. It has been used as an air compressor, exhauster and also for receiving the exhaust from a steam engine, taking the place, in that case of both condenser and air pump. The injector is not an economical device, but it is simple and convenient; it occupies a very small space, is not expensive and entirely free from severe strains on its durability; moreover, where a number of boilers are used in one establishment, it is very convenient to have the feeding arrangements separate, so that each boiler may be a complete generating system in itself and independent of its neighbors. The following text is intended to describe the instruments illustrated on pages 244, 246, 248 and 250. Fig. 517. Fig. 518. The “Manhattan” automatic injector is shown in perspective and outline upon page 244. This instrument is made by Messrs. Schaeffer & Budenberg of New York City. This injector is designed for portable and semi-portable engines and boilers, and is also adapted for stationary boilers requiring no high lift. Its main features are simplicity and positive automatic action. It works under pressures ranging from 30 to 150 lbs., either lifting or non-lifting. The letters in the outline cut refer to the parts: a. Steam Nozzle. The “Peerless” automatic injector is shown on page 246. This is, in effect, the same instrument as the “Manhattan” except it has a steam spindle with handle to regulate the flow of steam. See figure 514. Two classes of Peerless injectors are made, viz.: Class A—for high pressures ranging from 50 to 200 pounds. and they are stamped accordingly. They are adapted for any service requiring the lifting of water. Class A is made for lifts up to 12 feet. but if so ordered, they can be arranged for higher lifts. They may also be used as non-lifting injectors. The temperatures of feed water taken by these injectors, if non-lifting or at a low lift, can be as follows:
The spindle acts as a valve for the steam inlet; an extra seam valve is therefore not absolutely required, but recommended for convenience of detachment. The letters in Figs. 520-533, page 254, relate to the names of “the parts” of the Peerless injector. a. Steam Nozzle. The Monitor injector, Fig. 513, page 246, was designed originally for locomotive work. It consists mainly of two parts, viz., 1, the lifting device which raises the water into the injector and, 2, the forcing device which “picks up” the water and causes it to flow into the boiler. The Metropolitan double tube injector is shown in the two figures on page 248. These are made by the Hayden & Derby Mfg. Co. This instrument is of the double-tube design and in that particular resembles the Korting injector described on page 264. Both the lifting and forcing, as well as the overflow valves are controlled by one handle. The Metropolitan single tube injector is represented by the Figs. 517 and 518, page 250. The internal parts of this injector, as may be seen from the sectional engraving, are stationary. The steam is regulated by the handle, K, which is attached to the stem, M; the water supply adjusts itself automatically. The capacity of the leading injectors is nearly the same under similar working conditions as represented by the following Table.
The figure below shows how the connections or piping should be made in attaching the Manhattan and Peerless injectors. The dotted lines indicating pipe and fittings in connection with the suction represent the way the water supply is to be received from a tank located above the level of the injector. Fig. 519. The makers of these two instruments have kindly furnished the following general rules to govern their connection with steam supply: 1. Place injector in a horizontal position. (See illustrations 512 and 514.) The flap nozzle must in all cases open upward in direction of air valve. In taking injectors apart be careful to replace it in that position. 2. Take steam from the highest part of boiler; never connect to pipes furnishing steam for other purposes. 3. Have all joints perfectly tight, especially the suction pipe, as no injector will lift water unless atmospheric air is excluded. 4. Have all pipes thoroughly cleaned from red or white lead and scale before the injector is connected; it will save trouble afterwards. 5. All pipes must be of the same or larger diameter than the corresponding parts of injector. 6. Avoid all short bends, and have all pipes as short and straight as practicable. 7. Use a strainer at the end of suction pipe; the holes in the strainer should be small, but their total area larger than the area of the supply pipe. 8. Insert stop valves in suction, steam and delivery pipes, to facilitate disconnection in cleaning injector and check valve in delivery pipe. Figs. 520-533. 9. Have valve stems packed well; they often leak. 10. To remove incrustations caused by water containing lime or other impurities, place parts for a reasonable time in a bath of mineral oil or diluted muriatic acid consisting of 4 parts of water to 1 part of acid. Note.—The lettered parts shown above apply to both the “Manhattan” and the “Peerless” injectors. See page 252 for the names of the parts corresponding with the letters. The exhaust steam injector utilizes the escaping vapor from the engine cylinder, hence the saving in fuel and water is very marked where certain conditions are favorable. It condenses by means of the smallest possible quantity of cold water the largest possible quantity of exhaust steam and puts it into the boiler without the aid of any other power than the exhaust steam itself. It can be attached to any class of non-condensing engine, and its use increases the power both of the engine and boilers. Figs. 534 and 535. It is worked by waste steam, just as ordinary injectors are worked by live steam from the boiler. The first cost and subsequent wear and tear of pumps are avoided. The power required to work pumps, of whatever construction, is saved: the exhaust injector doing the same work by the condensation of waste steam. The waste steam, in passing through the injector, heats the feed-water to a temperature of about 190° F. The condensation in the injector of so large a quantity of waste steam reduces It is not uncommon for these injectors to form a vacuum of a half-inch of mercury within the exhaust pipe, which of course helps the engine to that extent. Fig. 536.—See page 260. These injectors work with great success on stationary engines and boilers, also on steamers, tugs, dredges, etc., as their operation during the roughest weather is not affected by the motion of the vessel. The high pressure exhaust steam injector is shown in Figs. 537 and 538—the last being an outline exhibiting the internal arrangement of the instrument: these injectors are made to work at all pressures up to and not exceeding 150 lbs. to the square inch. Fig. 537 and 538. The high pressure exhaust steam injector is worked by waste steam up to 75 lbs. pressure only, and a little live steam is introduced at the top of the injector to force water against pressures higher than 75 lbs. It will be noticed from sectional cut that the live steam does not come in contact with the water until after the exhaust steam has been condensed and has done its work. The exhaust steam alone gives an impetus to the water equal to 75 lbs.; it also heats it up to about 190° F. Its advantages are the same as those of the plain exhaust injector, the heat of the small jet of live steam which is used to overcome the excessive pressure being brought back into the boiler. It raises the temperature of feed-water up to 90° Fahr. if working against a pressure of 105 lbs., and up to 86° Fahr. against 120 lbs. boiler pressure. It is regulated in the same manner as the plain exhaust steam injector. It is not necessary to use live steam while working against any pressure below 75 lbs., when exhaust steam alone will suffice. Fig. 539 represents the piping of the high pressure exhaust steam injector, the operation of which is described in the following paragraphs: This injector can be worked under various conditions. 1. If boiler pressure does not exceed 75 lbs. per square inch, exhaust steam only is required. In this case steam is admitted by valve A. Fig. 539. 2. For pressures exceeding 75 lbs. exhaust steam is admitted as before, also a little live steam, slowly, by valve C. 3. If engine is not running, live steam is gradually admitted by valve B, so that it may expand in pipe F. In case of high boiler pressure additional live steam is introduced by valve C. To start this injector. 1. Open steam valves as described. 2. Then open water valve. 3. Regulate water valve, and, if necessary, screw up or down nut R at the lower end of injector until overflow ceases. If desired, a gauge indicating both pressure and vacuum (a compound gauge) can be furnished with exhaust steam injectors. Table of Sizes.—Pipe Connections.
The ejector is a low lift pump; it works on the same principle as that of an injector. It has less parts than the latter and is less expensive. The following table applies to ejectors. Table.
Figs. 540 and 541. The accompanying Figs. 540 and 541 represent an ejector with a foot strainer. The table, page 259, gives an idea of its pipe sizes and capacities. Application of ejectors. The Fig. 536, page 256, shows two ejectors applied in different ways. One is mounted to lift and force water, and the other to force only; the latter is submerged in the water to be elevated, and placed in a vertical position to reduce the condensation of operating steam to a minimum. In both of these examples of the use of the device it will be noted a strainer is attached to the suction pipe. The arrows show the direction of the flow of both the steam and water. Certain ejectors will not work well when the steam pressure is too high. In order to work at all the steam must condense as it flows into the combining tube. Therefore, when the steam pressure is too high, and the heat is very great, it is difficult to effect complete condensation; so that for high pressure steam good results can only be obtained with cool water. It would be well when the feed water is too warm to permit the ejector to work right, to reduce the pressure, and consequently the temperature of the steam supply, as low pressure steam condenses quickly, and therefore can be employed with better results than high pressure steam. Note.—This instrument is marketed as “Van Duzen’s steam jet pump” (Cincinnati, Ohio), and credit should be given the makers for the useful table on page 259. For high elevations and high temperature of liquids, ejectors should be submerged from three to six feet; the suction pipe should always be provided with a strainer and the makers of the instruments recommend the placing of a check valve in the force pipe to facilitate the cleaning of the suction pipe by steam, when made necessary through the raising of impure substances. To start the ejector open the steam valve slowly until the suction works satisfactorily, when full amount of steam should be quickly admitted. Fig. 542. Fig. 543. Fig. 544. A double tube ejector is represented in Fig. 542. This is calculated to use steam economically by reason of its having two tubes, besides it is well made and properly proportioned to raise water to high elevations. Fig. 543 is a cheaper form of apparatus and is designed to elevate water to very moderate heights and where a saving of steam is not of so much consequence as in localities where the price of coal is high. The jet pump presented in Fig. 544 is another compact form of this style of ejector and is adapted for its own particular class of work which is but little known to those unaccustomed to use these appliances. When working either an injector or ejector from a long lift or with a long pull through horizontal piping, it takes several minutes to exhaust the air from the pipe when steam is turned on, resulting in a considerable waste of steam each time the injector is started. This waste can be done away with by the use of a foot valve. Fig. 545. Fig. 546. Fig. 547. Universal double-tube injector (original Korting injector). This instrument is the combination of two jets (see Figs. 545 and 546); it is proportioned for extreme temperature and for quick and strong action, which includes maximum high suction. The discharge is into the upper jet, where the water receives the additional strong impulse to carry it into the boiler. The pressure and volume from the lower jet corresponds to the steam pressure, and this is as it should be to answer the requirements of the upper or forcing jet. The varying volume insures the proper working at high steam pressure as well as at low, and an increased pressure admits of increased high temperature. The action of the injector is thus explained; its favorable operation is due to the double-tube principle; the pieces composing the Korting injector are shown in the numbered cuts, page 263, and the names of the parts are given below. Number and name of piece. 1, Body; 2, handle lever; 3, side rods; 4, connecting fork; 5, cross head for shaft; 6, nuts for cross head; 7, starting shaft; 8, nuts; 9, yoke bar; 10, lower steam valve; 11, upper steam valve; 12, lower steam nozzle; 13, upper steam nozzle; 14, lower water nozzle; 15, upper water nozzle; 16, front body caps; 17, side body caps; 18, overflow nozzle; 19, check valve compressor; 20, overflow valve compressor; 21, stuffing-box; 22, fol. for stuffing-box; 23, nuts for stuffing-box; 24, cross head for overflow; 25, links for overflow; 26, pin for links; 27, screws; 28, bell cranks; 29, coupling nuts; 30, pipe unions; 31, spanner wrench; 32, sokt. nozzle wrench; 33, un. for cop. pipe.—Regulator complete replaces pieces 10 and 16. Table.
Note.—The above table relates to the double tube injector. The acid syphon pump, shown in Fig. 548 below, is used by many chemical works, in lifting their acids and other chemicals to be conveyed to any part of the building. The machine is made of lead, encased in an iron shell for strength, and fitted with a platinum steam nozzle to give that part durability. This device is named a syphon pump because it becomes a syphon by turning down the delivery pipe and making that end longer than the suction end. The apparatus, shaded in the figure, is really a jet pump and it is simply used to operate the syphon, i.e., by turning on the steam the acid will flow through the syphon. At this point the steam should be shut off and the flow of acid will continue. Fig. 548. Noiseless Water Heater. This instrument, Fig. 549, is used for warming of liquids; it avoids the noise that is otherwise caused by the action of steam led for that purpose direct into cold liquids. In operation, the liquid is drawn through the holes in body and discharged through shank, causing a circulation of the liquid in tank. Table of Dimensions.
Fig. 549. Water Pressure Ejector. This instrument, Fig. 550, is worked by water pressure and used to advantage in excavations, cellars, etc., where water pressure can be had and the required elevation does not exceed 12 feet. It has to be inserted into the water pressure pipe in such a manner that it will be entirely covered by the water to be raised. It will raise double the quantity of water which it obtains from the pressure pipe, i.e., it will deliver two gallons for every one it receives from the pressure pipe. Fig. 550. Table of Dimensions.
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