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 From 
 
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 LIBRARY 
 HKiymSJJY OF CALIFORNIA 
 
 PaVis 
 
CONDENSERS. 
 
 A series of Lectures and Articles upon the Subject 
 reprinted from the columns of 
 
 NEW YORK: 
 
 The Power Publishing Company, 
 
 World Building. 
 
 1901. 
 
 LIBRARY 
 
 UNIVERSITY OF CALIFORNIA 
 
 DAVIS 
 
Entered accotding to act of Congress, in the year 1900, by The Power Publishing 
 Company, in the office of the Librarian of Congress at Washington. 
 
LECTURE VIII.— CONDENSERS. 
 
 BY F. R. LOW. 
 
 If you build up a solid column of bricks the pressure which it 
 exerts on its base will increase directly as the height of the col- 
 umn. A column ten feet in height will press twice as hard on 
 its base as a column five feet high, and a column ioo feet high 
 ten times as hard as a io-foot column. 
 
 Now, the point I want to make is that the pressure per square 
 inch of base depends altogether on the height and not on the 
 width or diameter of the column. A column 2 feet square will, 
 it is true, press on its base with four times the pressure of a col- 
 umn one foot square and of the same height, because there are 
 four times as many bricks in it and it weighs four times as much, 
 but there is also four times as much base to it, so that the pres- 
 sure per square inch of base is entirely independent of the cross 
 section and depends upon the height alone. 
 
 The same thing is true of water. A cubic foot of fresh water 
 weighs 62.355 pounds at 62 degrees Fahrenheit. It is easy to 
 remember this weight approximately, for it is the same as the de- 
 grees and 62 is a standard temperature in dealing with water. A 
 cubic foot rests on a base of 144 square inches and is a foot high, 
 so that the pressure per square inch on the base would be 
 
 62.355 ~r-T44 — °-433 of a pound 
 and for every foot in height that we build our column or fill our 
 pipe with water we gain 0.433 °f a pound pressure per square 
 inch. If one foot or 12 inches gives us 0.433 of a pound it would 
 take a column 
 
 12 -— .433 = 27.71 inches 
 in height to exert a pressure of- one pound per square inch. For 
 
Fluid Pressure is Dependent upon Height of Column. 
 
 every 27.71 inches in vertical height between the point at which 
 you are measuring and the top of a column of still water there wilt 
 be a pressure of a pound to the square inch, and it makes no dif- 
 ference whether you are measuring the pressure at the bottom of 
 a one- eighth inch pipe, a twenty foot stand-pipe, or a lake, or the 
 ocean itself. Every once in a while we have to explain this to- 
 the man who believes it takes more power to feed into the bot- 
 tom of a tank than into the top, on account of the weight of 
 water in the tank. The bottom of the tank holds up all the 
 water except the column directly over the opening of the deliv- 
 ery pipe, so that the additional pressure on the pump is due only 
 to the depth of water in the tank, not to the size of the body, 
 and it is impossible to feed into the top without increasing the 
 height of the column fully as much. It makes no difference 
 whether the height is due 
 to the depth of the water 
 inside the tank or an ad- 
 ditional length of pipe 
 outside. The difference 
 between the water and 
 the column of bricks is 
 that while the pressure 
 of the latter can act only 
 vertically that of the 
 water can act in all di- 
 rections so that as you 
 
 lower a body into the water the pressure upon its surface in all 
 directions increases one pound per square inch for every 27.71 
 inches of depth of water above it. In Fig. 1, for instance, the 
 pressure due to the column of water P will act upward upon the 
 piston A and sidewise upon the pistons B and G as well as down- 
 ward upon the piston D. 
 
 We live at the bottom of an ocean of air. The winds are its 
 currents, we can heat it, cool it, breathe and handle it, weigh it, 
 and pump it as we would water. The depth of this atmospheric 
 ocean cannot be determined as positively as could one of liquid, 
 for the air is elastic and expands as the pressure decreases in the 
 upper layers. It is variously estimated at from 30 to 212 miles. 
 We can, however, determine very simply how much pressure it 
 exerts per square inch. 
 
 
 
 
 
 
 
 ^1 
 
 
 
 
 
 
 r 
 
 P 
 
 / 
 
 1 
 
 : 
 
 
 
 =fe= 
 
 
 ;- 
 
 z^^s. 
 
 
 
 B 
 
 ; — ; ' p 
 
 
 
 —~^== = 
 
 
 
 Fi 
 
 9- 
 
 
 EfT^ 
 
 
 
 
 
 
Measuring the Pressure of the Atmosphere. 
 
 Here is a U-tube, Fig. 2, into which a quantity of mercury 
 "has been poured. It stands at an equal height in both legs. Into 
 one leg I pour some water on top of the mercury, and the mer- 
 cury is depressed in that leg, and rises in the other. ^ 
 The difference in level of the mercury is a meas- 
 ure of the weight or downward pressure of the 
 water. 
 
 The mercury below the line A B balances in 
 lx>th legs and the mass of mercury above that 
 line in the right leg just balances the weight or 
 pressure of the water in the other. The pressure 
 of the atmosphere makes no difference in this ex- 
 periment, for it is exerted on both columns equal- 
 ly. Now we can find the pressure of the atmos- Fig. 2. 
 phere in a similar way by making it act on one 
 end of the mercury column as does the water here and keeping it 
 away from the other. 
 
 Here is a glass tube about a yard in length and filled with mer- 
 cury. Closing one end 
 with my thumb to pre- 
 vent a premature escape, 
 I invert it in a bowl of 
 mercury as in Fig. 3. 
 This is handier than the 
 U-tube but the principle 
 is the same. The bowl 
 is in effect the other leg 
 of the tube and no mat- 
 ter what its size may be 
 the atmosphere exerts a 
 certain pressure on each 
 square inch of its surface, 
 except at the point 
 covered by the tube, 
 and here the mercury 
 rises until it forms a 
 column high enough to 
 exert the same pressure 
 per square inch, so that the height of the column is a measure 
 
4 Nature and Measurement of a Vacuum. 
 
 of the atmospheric pressure. This column will be approximate- 
 ly 30 inches, and as a cubic inch of mercury weighs about a 
 half a pound, each two inches of height will be equal to a pound 
 pressure, so that the pressure exerted by the atmosphere is about 
 1 5 pounds per square inch. This pressure depends first upon the 
 nature of the atmosphere. You know that steam or aqueous 
 vapor is lighter than air at the same pressure, so the more moist- 
 ure there is in the air the lighter the column of atmosphere 
 above us, and the less the height to which our column of mer- 
 cury will rise to balance it. Also the warmer the air becomes 
 the lighter it is. Again, if we carry our apparatus to the top 
 of a high mountain we shall find a considerable difference in the 
 height of the column, because we have lessened the height of 
 the column of air above us. This arrangement, which is 
 known as a "barometer," is therefore of use in indicating coming 
 changes in the weather, and elevations above the sea level, at 
 which our experiment is supposed to have been made. 
 
 We are then subjected all the time to a pressure of 15 pounds 
 to the square inch all over our bodies, yet we suffer no inconven- 
 ience, in fact, it took mankind a long while to find it out, be- 
 cause the pressure is the same in all directions, it is exerted in- 
 side as well as out, and there is no unbalanced pressure. It is 
 only when the atmospheric pressure is removed from one side and 
 allowed to act upon another that we get any effect. In a space 
 from which the air has been removed without allowing anything 
 else to enter, a "vacuum" is said to exist, and the vacuum is 
 more or less complete according to the more or less complete re- 
 moval of the air. In the space A in Fig. 3, exists the most per- 
 fect vacuum we are able to create, for the mercury in receding 
 has left nothing behind it, except possibly a little mercurial va- 
 por if there have been no air bubbles and no moisture between 
 the mercury and the glass. With this complete vacuum above it 
 the mercury will rise about 30 inches, and we would say that we 
 had "30 inches of vacuum." What we mean is that the pressure 
 has been so completely removed from the space A that the at- 
 mospheric pressure is able to support 30 inches of mercury 
 against the pressure that is left. Suppose we let a little air into 
 A. The mercury would fall more or less according to the amount 
 of air admitted, because this air would exert some pressure, there 
 
Nature and Measurement of a Vacuum. 5 
 
 would be less difference between the pressure in A and that of 
 the atmosphere, and the atmosphere would be able to support a 
 lesser column against this greater pressure. If the column now 
 was 18 inches high we would say that we had 18 inches of vac- 
 uum, and should mean that the atmospheric pressure could sup- 
 port 18 inches oi mercury against the pressure in our vacuum. 
 These are the "inches" of vacuum upon the ordinary vacuum 
 gage. When the pointer stands at 26 inches it means that there 
 is difference enough between the pressure in the condenser and 
 that of the atmosphere to support a column of mercury 26 inches 
 high. If with an absolute vacuum the barometer stood at 30 
 inches, and if a cubic inch of mercury weighed half a pound the 
 atmospheric pressure would be 15 pounds, and two inches would 
 equal one pound. As a matter of fact the height of the barome- 
 ter varies and mercury weighs only .49 of a pound to the cubic 
 inch, so that the atmospheric pressure is nearer 14.7 than 15 
 pounds. When you put your hand over an opening into a space 
 containing a vacuum you feel it drawn to and held down very 
 hard upon the opening. This is due not to any attractive power 
 of the vacuum, but to the pressure of the atmosphere upon the 
 back of your hand unbalanced by an equal pressure on the area 
 in contact with the opening to the vacuum. 
 
 Here is an implement which every schoolboy knows under the 
 name of a "sucker," a circular pad of leather, thick, but pliable, 
 with a string through its center. It has been soaking in water. 
 I press it against the smooth wooden seat of this chair and am 
 able, you see, to lift the chair with a string. The boys used to 
 get themselves into disrepute with the householders in the vicin- 
 ity of the school by pulling the bricks out of the sidewalk in this 
 way. This action is not due to any attractive or adhesive prop- 
 erty of the leather, but to the fact that there is a pressure of 
 about 15 pounds per square inch pushing the leather against the 
 chair, and the atmosphere owing to the more or less complete 
 contact of the wet leather with the surface on which it rests can- 
 not get to the under surface to balance it. The disk is four 
 inches in diameter, having an area of 12.5 square inches, and the 
 atmosphere exerts a pressure on its surface of 14.7 X I2 - 5 = 
 183.75 pounds with which the "sucker" would resist separation 
 from the surface to which it was attached, if the pressure was 
 
How Water is Lifted by Means of a Vacuum. 
 
 entirely removed from its under-side, and other surface, and the 
 leather perfectly air tight. 
 
 We are accustomed to say that water is ' 'sucked up' ' or ' 'drawn 
 up" by a pump as though there was some pulling property to the 
 vacuum which it creates, when as a fact the water is pushed up 
 by the atmospheric pres- 
 sure acting on the sur- 
 face of the water in the 
 well. If in Fig. 3, we 
 had a tube of water in- 
 stead o f mercury w e 
 should find that the 
 water would rise in it 
 about 34 feet instead of 
 30 inches. We have 
 seen that it takes a col- 
 umn of water 27 71 in- 
 ches high to exert a 
 pressure of one pound, 
 then the atmospheric 
 pressure of 14.7 pounds 
 could support a column 
 of 
 
 2771 X r 4 .7 =33 94 ft 
 12 
 
 In Fig. 4, we have a 
 steam pump drawing 
 water from a well. 
 Steam acting on the pis- 
 ton A pushes the piston 
 B toward the left, forcing 
 the water before it 
 through the upper valve 
 to the discharge pipe and leaving behind it a more or less complete 
 vacuum in the space C. Connected to the space C through the 
 lower valves is the pipe P, the lower end of which is immersed in 
 the water of the well. Here we have a reproduction (Fig. 4) of 
 Fig. 3. The well is the bowl, the pipe P is the glass tube, the 
 vacuous space C corresponds with the vacuous space A. There 
 
Limitations of Lift. 
 
 is this difference, however, the pipe P is not so long but that the 
 atmospheric pressure can force the water clear through it, through 
 the valve into the cylinder C, ready to be forced out again when 
 the piston moves in the other direction. The difference in pres- 
 sure between the cylinder and the atmosphere must be sufficient 
 to lift the water from the level in the well to the level of the 
 pump cylinder, to lift the valve and to induce a flow sufficiently 
 to keep the cylinder full behind the receding piston, and these 
 considerations limit the distance that we can place a pump above 
 its source of supply, in other words its "lift." In the first place 
 we cannot get a perfect vacuum in contact with water. You re- 
 member that the boiling point of water de- 
 pends upon the pressure. In a boiler with 
 a pressure of 60 pounds by the gage, the 
 water will not boil until it is over 300 . 
 Under the pressure of the atmosphere it 
 boils at 212 , and as you reduce the pres- 
 sure below that of the atmosphere the boil- 
 3 ing point lowers rapidly. You can even boil 
 water at 32 ° if you reduce the pressure 
 power.y.r. sufficiently. In the table on page 8 are 
 
 Fl £- 5- shown the relations of pressure and tempera- 
 
 ture for water at from 32 ° to 212 . This means that if we had 
 an arrangement like Fig. 5, starting with a complete vacuum in 
 chamber A the mercury in the tube would not rise above the level 
 in the cup because there is a complete vacuum both in A and B. 
 Now if water of 32 ° be introduced into A it would boil and give off 
 vapor until the pressure in A arose to .089 of a pound, and the 
 mercury would rise in B 181 thousandths of an inch. A complete 
 vacuum as given by this table is 14.7 pounds, or 29.922 inches, 
 but the introduction of the water even at 32 ° has reduced the 
 vacuum to 29.922 — .181=29.741 inches. The heat necessary to 
 convert the water into vapor, which you will remember from an 
 earlier lecture was considerable in amount and was called the latent 
 heat, coming from the water and its surroundings, the water would 
 be frozen, and I have seen ice made by simply spraying water into 
 a space in which a high degree of vacuum was maintained. If 
 the water was 6o° the vacuum would be impaired .571 of an inch 
 or . 254 of a pound. This is the reason it is so difficult to pump hot 
 
Temperature of Steam Below Atmospheric Pressure. 
 
 water. If the water in Fig 4 was 150 the space Cleft by the 
 piston, instead of being a nearly complete vacuum, would be filled 
 with steam of 3. 708 pounds pressure, leaving only 14. 700 — 3. 708= 
 
 
 Pressure. 
 
 Vacuum. 
 
 Temperature 
 
 
 
 
 
 Inches of 
 
 Lbs. per 
 
 Inches of 
 
 Lbs. per 
 
 
 mercury. 
 
 square inch. 
 
 mercury. 
 
 square inch 
 
 Fahrenheit. 
 
 Inches. 
 
 
 
 • 
 
 32° 
 
 .181 
 
 .089 
 
 29 741 
 
 14.611 
 
 35° 
 
 .204 
 
 .100 
 
 29 718 
 
 14 600 
 
 40° 
 
 .248 
 
 .122 
 
 29 674 
 
 14.578 
 
 45° 
 
 .299 
 
 .147 
 
 29.623 
 
 14.553 
 
 50° 
 
 .362 
 
 .178 
 
 29.560 
 
 14 522 
 
 55° 
 
 .426 
 
 .214 
 
 29.496 
 
 14.486 
 
 60° 
 
 .517 
 
 .254 
 
 29.405 
 
 14 446 
 
 65° 
 
 .619 
 
 .304 
 
 29 303 
 
 14.396 
 
 70° 
 
 .733 
 
 .360 
 
 29,189 
 
 14 340 
 
 75° 
 
 .869 
 
 .427 
 
 29.053 
 
 14.273 
 
 80° 
 
 1024 
 
 .503 
 
 28.898 
 
 14 197 
 
 85° 
 
 1205 
 
 .592 
 
 28 717 
 
 14 108 
 
 90° 
 
 1.4L0 
 
 .693 
 
 28.512 
 
 14 007 
 
 95° 
 
 1.647 
 
 .809 
 
 28.275 
 
 13.891 
 
 100° 
 
 1917 
 
 .942 
 
 28.005 
 
 13.758 
 
 105° 
 
 2.229 
 
 1.095 
 
 27.693 
 
 13 605 
 
 110° 
 
 2 579 
 
 1.267 
 
 27 343 
 
 13 433 
 
 115° 
 
 2 976 
 
 1.462 
 
 26 846 
 
 13.238 
 
 120° 
 
 3.430 
 
 1685 
 
 26 492 
 
 13,015 
 
 125° 
 
 3.933 
 
 1932 
 
 25 989 
 
 12.768 
 
 130° 
 
 4 509 
 
 2 215 
 
 25.413 
 
 12.485 
 
 135° 
 
 5.174 
 
 2 542 
 
 24.748 
 
 12.158 
 
 140° 
 
 5.860 
 
 2 879 
 
 24.062 
 
 11.821 
 
 145° 
 
 6 662 
 
 3 273 
 
 23.262 
 
 11.427 
 
 150° 
 
 7 548 
 
 3 708 
 
 22.374 
 
 10 992 
 
 155° 
 
 8.535 
 
 4 193 
 
 21.387 
 
 10 507 
 
 160° 
 
 9.630 
 
 4.731 
 
 20.292 
 
 9.969 
 
 165° 
 
 10 843 
 
 5 327 
 
 19.079 
 
 9.373 
 
 •170° 
 
 12.183 
 
 5 985 
 
 17.739 
 
 8 715 
 
 175° 
 
 13.654 
 
 6 708 
 
 16.268 
 
 7 992 
 
 180° 
 
 15.291 
 
 7 511 
 
 14.631 
 
 7 189 
 
 185° 
 
 17.044 
 
 8.375 
 
 12.878 
 
 6 325 
 
 190° 
 
 19 001 
 
 9 335 
 
 10.921 
 
 5 365 
 
 195° 
 
 21139 
 
 10 385 
 
 8 783 
 
 4 315 
 
 200° 
 
 23.461 
 
 11526 
 
 6.461 
 
 3 17,4 
 
 205° 
 
 25.994 
 
 12 770 
 
 3.928 
 
 1930 
 
 2'0° 
 
 28.753 
 
 14 126 
 
 1.169 
 
 .574 
 
 212° 
 
 29.922 
 
 14 700 
 
 0.000 
 
 0.000 
 
 10.992 pounds to raise the water and force it into the pump. If 
 the water was 212 it would give off steam equal in pressure to 
 that of the atmosphere, and we have no available force at all. 
 
Absolute Pressure. 9 
 
 These relations between pressure and temperature are simply 
 those for aqueous vapor or steam. When air is present the pres- 
 sure will be higher for a given temperature. For this reason the 
 vacuum or pressure in a condenser is not that due to the temper- 
 ature of its contents as given in a table of the physical properties 
 of steam for it is not steam alone with which we are dealing but 
 a mixture of steam and air. 
 
 You are now in a position to appreciate what is meant by ' 'ab- 
 solute" pressure. It is the pressure reckoned from a complete 
 vacuum as are the pressures in the above table, and atmospheric 
 pressure which is the zero of the ordinary steam gage and of what 
 
 Fig. 6. 
 
 is referred to as "gage pressure" is about 14.7 pounds absolute, 
 varying with the barometer. In order to get the "absolute" 
 pressure then we must add the barometer's pressure, 14.7 pounds, 
 or 15 if we do not care to be very precise, to the pressure indi- 
 cated by the gage. The steam tables are given in absolute 
 pressures, and we have to take the absolute, not gage pressure, 
 when laying out the expansion line, or figuring problems in 
 which expansion is involved. 
 
 There is this difference between pumping air and water, that 
 
io Pumping Air. 
 
 water is either there or not there; there is no half way about it. 
 It is neither expansible nor compressible by change of pressure, 
 and it may be handled in mass. In Fig. 6, for instance, we have 
 a closed vessel of water at A and another of air at B. Now when 
 the pump connected with A is operated a volume of, say one- 
 fifth, of the water is removed, the water left in the tank falls, 
 there is nothing to take its place, and a practically complete vac- 
 uum is left behind. But in the case of the air, when one-fifth of 
 the volume is removed by a stroke of the pump, the remainder, 
 instead of assuming a level and leaving a vacuum at the top as 
 the water did, expands and fills the whole space. Before the 
 pump was operated the air was at atmospheric pressure, say 15 
 pounds to the square inch absolute. The operation of the pump 
 removes one-fifth of its volume, and the remaining four-fifths ex- 
 pands to fill the complete volume. In this expansion, its pres- 
 sure would be reduced to four-fifths of the former pressure, equal 
 to 1 2 pounds, so that instead of having at once a complete vac- 
 uum in the chamber as with the water, we have only reduced the 
 pressure three pounds below the atmospheric pressure outside, 
 and if a column of mercury be connected with the chamber, as 
 shown at B, we shall find that in the case of the air it will only 
 stand about 6 inches in height, for the sustaining force is the dif- 
 ference between the inside and outside of the chamber, which is 
 15 — 12=3 pounds, and as one inch in height exerts a pressure 
 of one-half pound per square inch on its base, 3 pounds would 
 balance 3-^.5 = 6 inches in height. In this case there is said 
 to be 6 inches or 3 pounds of vacuum in the vessel. 
 
 By further reducing the air in the vessel, we can produce great- 
 er differences in pressure between the inside and outside and the 
 atmosphere will press the harder toward the inside of the vessel, 
 its pressure being measured in the inches of mercury which it 
 will lift, or the pressure per square inch which it exerts. All 
 questions in regard to a vacuum become plain when we consider 
 that the atmosphere itself exerts a pressure of nearly 15 pounds, 
 and measure everything from an absolute zero 15 pounds below 
 the atmospheric pressure. 
 
 When an engine is run without a condenser the steam with 
 which the cylinder is filled at the end of the stroke has to be 
 
Production of Vacuum bv Condensation. 
 
 1 1 
 
 forced out against the pressure of the atmosphere, about 15 
 pounds to the square inch. It is possible from the nature of 
 steam to remove the atmospheric pressure with, in most cases, a 
 decided gain. One pound of steam at atmospheric pressure oc- 
 cupies 1 ,642 times as much room as it does in the state of water. 
 If therefore when the stroke has been completed and we are 
 ready for the piston to come back we inject a little cold water 
 into the spent steam, it will condense to about one 1600th of 
 
 Fie\ 7. 
 
 its volume, and leave a vacuum into which the piston can return 
 without having to force back the atmosphere. This is the way 
 the earlier engines were run, the condensation taking place in the 
 cylinder itself, and, moreover, the vacuum was all that made the 
 engine operative, for the steam carried was bul little above atmos- 
 pheric pressure. Watt's introduction of the separate condenser 
 was his greatest contribution to the steam engine, and constituted 
 
12 
 
 Gain by Condeiisation . 
 
 his most important invention, for he was not as you know the in- 
 ventor of the engine, but its improver. The operation of the 
 condenser is shown in Fig. 7. The denser steam in the stuffing 
 box end of the cylinder is pushing the piston to the left, forcing 
 the spent steam of the previous stroke to the condenser where, 
 instead of having to be forced out against 1 5 pounds pressure of 
 the atmosphere, it is condensed by coming into contact with a 
 spray of cold water. The condensed water, the water of injec- 
 tion and the air which has entered with the steam and by leak- 
 age are drawn out by an "air pump," and the comparatively 
 small volume which it has to expel against the atmospheric pres- 
 sure, leaves a large margin a 95 lbs, b c 
 
 . , - ° I ABSOLUTE ' 
 
 of power gained after that 
 required to run the pump 
 is deducted. 
 
 L,et us first consider the 
 nature and extent of the 
 saving due to a condenser, 
 and when it is and is not 
 advisable to use it. 
 
 Suppose we have an en- 
 gine with an initial pres- 
 sure of 80 pounds gage,= 
 95 pounds absolute, cutting 
 off at one-third. The 
 mean effective pressure, if the engine ran non-condensing and 
 made the perfect diagram represented by the full lines in Fig. 8, 
 would be 51.25 pounds. If we put on a condenser and reduce 
 the back pressure from that of the atmosphere, say 15 pounds ab- 
 solute, to 3 pounds absolute, the diagram, to give the same mean 
 effective pressure representing the same load on the engine, would 
 take the form shown by the dotted lines. • 
 
 In the non- condensing diagram, the boiler has to fill the cylin- 
 der up to the point C, and the volume of steam at cut-off is pro- 
 portional to the line A C. In the condensing engine the steam 
 is cut off at B, and the steam is proportional to the line A B. 
 Now A C is .33^3 of the volume of the cylinder and A B is only 
 .23256, so we have apparently saved 
 
 Fig, 8. 
 
53 LBS. ABSOLUTE 
 
 Gain by Condensation. *3 
 
 -33333— 23256 ^ ioo== 
 
 •33333 
 about 30 per cent, (clearance neglected). 
 
 Again, suppose we have a throttle governed engine cutting off 
 at two-thirds the stroke, with an initial pressure of 50 pounds, 
 gage, =65 absolute, running non-condensing, it would make, 
 theoretically, the diagram indicated by the solid lines in Fig. 9, 
 and exert a mean effective pressure of 45.62 pounds. If we put 
 on a condenser and reduce the back pressure to 3 pounds, in which 
 case we should as before realize a vacuum of 12 pounds or 24 
 inches, the cut-off would remain at two-thirds, but the initial 
 pressure would be lowered, as shown by the dotted lines, to 38 
 pounds. While the volume up to cut-off is the same in each case, 
 95 lbs.absolute the pressure is lowered, and 
 
 the same volume of lower 
 pressure steam weighs less. 
 ^ Suppose the size of the 
 cylinder was such that it 
 took a cubic foot to fill it up 
 to cut-off. Then, when 
 making the non-condens- 
 absolute zero Power. s. t. ing diagram shown by the 
 
 Fig. 9. solid lines in Fig. 9, it 
 
 would take a cubic foot of 50- pound steam (65 absolute) which 
 would weigh .1519 of a pound. When making the condensing 
 diagram shown by the dotted lines, it would take the same 
 volume of 53-pound (absolute) steam, which would weigh .1255 
 of a pound. An apparent saving of 
 
 • I 5 I 9 - I2 55 >< 100 = 17.38 per cent. 
 .1519 
 This is not, however, a pure saving. The most important 
 charge against it is the reduction of available temperature for the 
 feed water. With an engine exhausting at atmospheric pressure 
 the exhaust steam has a temperature of 212 , and by the use of a 
 suitable heater it is possible to get the feed water nearly as hot. 
 With a condenser in which the absolute pressure is reduced to 
 three pounds, the temperature of the exhaust steam is only 
 141 62, and the temperature of the hot- well, or the discharge 
 from the air-pump, would be in practice from no° to 120 . Very 
 
 ATMOSPHERIC LINE 
 
14 Loss in Feed Water Temperature. 
 
 careful practice might raise it to 130 but the temperature of the 
 hot-well will always be considerably less than that due to the 
 pressure of the steam or vapor in the condenser, on account of 
 the impossibility of bringing every particle of steam into contact 
 with the water when only the exact quantity of water theoreti- 
 cally needed to condense it is used, and the raising of the pres- 
 sure in the condenser by the presence of air without a corres- 
 ponding increase of the temperature. Suppose the hot-well tem- 
 perature is no° as against the 210 that we might have by run- 
 ning non-condensing. There would be a loss of approximately 
 10 per cent, for there is a gain in efficiency of one per cent for 
 about each ten degrees we heat the feed water. Even if we kept 
 the hot- well up to 130 there would be a fall in the available tem- 
 perature of feed of 8o°, or approximately eight per cent. 
 
 Again, it takes a great deal of water to condense the steam, 
 and all this water, as well as the condensed steam and the air, 
 which has worked in with it and by leakage, must be pumped out 
 against the pressure of the atmosphere, so that the cost of sup- 
 plying the condenser with water and of operating the air pump 
 must be deducted from the apparent gain. There is also the in- 
 terest on the extra cost of the condenser, the extra repairs, sup- 
 plies, insurance and attendance if the condenser plant is large 
 enough to require especial attention. 
 
 Here is a little extract from Peabody's Steam Tables, giv- 
 ing the amount of the heat contained in a pound of steam at 
 absolute pressures of from 10 to 25 pounds, or from about 5 
 pounds below the atmosphere to about 10 pounds above. The 
 column marked "Heat of the Liquid" gives the number of 
 heat units that we would have to put into a pound of water 
 to bring it from 32 ° up to the boiling point (given in the 
 second column), at the corresponding pressure in the first col- 
 umn. It is unnecessary to tell those of you who have read the 
 previous lectures that a "heat unit" or "British Thermal Unit" 
 is the amount of heat necessary to raise a pound of water one de- 
 gree. In the column marked "Heat of Vaporization" is given 
 the "latent heat" or the number of heat units necessary to evap- 
 orate the pound of water into steam after it has been raised to the 
 boiling point. The "Total Heat" is the sum of the two. Now 
 suppose, the terminal pressure in the cylinder, that is, the. pres- 
 
Water Required to Condense a Pound of Steam. 
 
 *5 
 
 sure at the time the exhaust valve opens, is 5 pounds above the 
 atmosphere, or say 20 pounds absolute, then every pound of steam 
 used will carry to the condenser 1151.5 heat units. Suppose the 
 hot- well temperature is 120 . A pound of water at 120 con- 
 tains 88.1 heat units above 32 . Suppose again that the tem- 
 perature of the injection water was 6o° . A pound of water at 
 6o° contains 28.12 heat units above 32 . Then each pound of 
 water in raising from 60 to 120 will absorb 88.1 — 28.12 = 59.88 
 heat units. 
 
 To condense the pound of steam and reduce it to water of 
 120 we must take from it 1151.5 — 88.1= 1063.4 heat units. 
 
 A 
 
 4ft 
 
 "d 
 
 0" 
 
 
 Pressure, 
 Pounds per 
 Square Inc 
 
 mperature, 
 grees 
 Fahrenhei 
 
 3 
 
 w 
 
 03 
 A 
 
 +3 
 
 CO 
 -t-a 
 
 c 
 
 CM O 
 
 OS 
 
 3 J 
 
 03 Fh 
 
 «| 
 
 03 13 
 
 HA 
 
 O 
 
 O 
 
 > 
 
 10 
 
 193 25 
 
 1619 
 
 1140.9 
 
 979.0 
 
 11 
 
 197 78 
 
 166 5 
 
 1142 3 
 
 975 8 
 
 12 
 
 201 98 
 
 170 7 
 
 1143.6 
 
 972.9 
 
 13 
 
 205 89 
 
 174.6 
 
 1144.7 
 
 970 1 
 
 14 
 
 209.57 
 
 178.3 
 
 1145 8 
 
 967.5 
 
 15 
 
 213.03 
 
 181.8 
 
 1146.9 
 
 965 1 
 
 16 
 
 216 32 
 
 185 1 
 
 1147.9 
 
 962.8 
 
 17 
 
 219 44 
 
 188 3 
 
 1148 9 
 
 960.6 
 
 18 
 
 222 40 
 
 19! 3 
 
 1149 8 
 
 958.5 
 
 19 
 
 225.24 
 
 194 1 
 
 1150 7 
 
 956.6 
 
 20 
 
 227.95 
 
 196 9 
 
 1151.5 
 
 954.6 
 
 21 
 
 230 55 
 
 199 5 
 
 1152.3 
 
 952 8 
 
 22 
 
 233.06 
 
 202 
 
 1153.0 
 
 9510 
 
 23 
 
 235 47 
 
 204 5 
 
 1153 7 
 
 949.2 
 
 24 
 
 237.79 
 
 206 8 
 
 1154.4 
 
 947 6 
 
 25 
 
 240 04 
 
 209 1 
 
 1155.1 
 
 946 
 
 As one pound of water will absorb 59.88 units it will require to 
 
 condense each pound of steam 
 
 1063.4 ~^~ 59-88 = 17.7 pounds of injection water. 
 
 It will be noticed that the number of heat units absorbed by 
 one pound of water is very nearly the difference in temperature 
 between the injection water and the hot-well. This difference 
 in the case in question would have been 120 — 60 = 60 heat 
 units, and is near enough in any case for practical purposes. To 
 find the amount of water required for a condenser, subtract the 
 
1 6 Cooling Water Required for a Given Engine. 
 
 heat units contained in a pound of water at the hot-well temper- 
 ature from the number of such units contained in a pound of 
 steam of the terminal pressure. These values can be gotten from 
 a table of the Physical Properties of Steam, to be found in any 
 engineer's reference book. Divide this value by the difference 
 between the temperature of the injection and of the hot- well, or 
 by the rise in temperature of the circulating water in the case of 
 the surface condenser, and you get the number of pounds of in- 
 jection or circulating water required per pound of steam. Mul- 
 tiply this by the number of pounds of steam required per hour 
 per horse-power, and you get the injection per hour per horse- 
 power. Multiply this again by the horse- power developed, and 
 you get the injection required to run a given engine with a given 
 load. 
 
 When the only water available for injection is foul, and would 
 make a mixture in the hot- well, that would not do to feed to the 
 boilers, ' a surface condenser may be used. This is the general 
 practice on sea-going steamers where the injection water is salt, 
 and it is necessary to use the same boiler water over and over. 
 Did you ever think what an immense amount of water is boiled 
 into steam to run one of the great liners ? The Paris has 30,000 
 horse-power. Suppose she runs on 13 pounds of steam per hour 
 per horse-power, her boilers would evaporate over a million gal- 
 lons of water a day, a good supply for a sizable town. Of course 
 they cannot afford to foul this by mixing the salt sea water with 
 it, so they condense it by letting it come in contact with metal 
 surfaces kept cool by sea water flowing upon the other side, but 
 always separated from the condensed steam. In this way it will 
 be seen the cooling or circulating water is kept entirely separate 
 from the condensed steam and the latter can be safely returned 
 to the boilers, while any sort of non-corrosive liquid can be used 
 for cooling purposes. We have heard of plants in large cities 
 where water was taken from the sewer, passed through a surface 
 condenser, and returned to the sewer again. 
 
 It will be noticed that the exhaust steam carries to the conden- 
 ser a very large percentage of the heat which it brings from the 
 boiler. A pound of steam at 80 pounds gage, 95 absolute, con- 
 tains 1 1 80. 7 heat units. Suppose 20 pounds of this steam are 
 required per hour per horse-power. Then 20 pounds of steam 
 
Where a Condenser is not Advisable. 17 
 
 will do 33,000 X 60 — 1,980,000 foot pounds of work, one pound 
 will do 1,980,000-1-20= 99,000 foot pounds. As one heat unit 
 is equal to 778 foot pounds, the number of heat units transformed 
 to work would be 99,000 -f- 778=127. 4 heat units. 
 1180.7 — 127.4 = 1053.3. 
 We have 1 180.7 units of heat taken from the boiler, 127.4 of 
 them converted into work and the balance, barring the trifling 
 loss from radiation, going out in the exhaust. It follows that if 
 we have any use for heat at anything under the temperature of a 
 reasonable exhaust, it would be bad engineering to let this heat, 
 which might be applied to the purpose, escape into the river in 
 the overflow from a hot-well. One case then where it is inad- 
 visable to use a condenser is where it is possible to use the ex- 
 haust steam to advantage. 
 
 Again, suppose we had 80 pounds initial pressure and instead 
 of cutting off at one quarter we carried the 80 pounds for the full 
 stroke, and exhausted at atmospheric pressure our mean effective 
 pressure would be 80 pounds. Now, if we put on a condenser 
 giving us 12 pounds of vacuum, we must reduce the initial to 68 
 pounds gage. The volumes used would be the same in both 
 cases. Steam of 80 gage (95 absolute) pressure weighs .2165 of 
 a pound; at 68 pounds gage (83 absolute), .1908, a saving of 
 
 .2165 .1 90S vy 
 
 - - — X 100= 1 1. 8 per cent. 
 
 .2165 
 
 Now if we lose ten per cent by reducing the temperature of 
 our feed water, and it takes two per cent to run the air pump, we 
 shall be worse off with the condenser, than without it, to say 
 nothing of the investment in it, the cost of oiling, packing, at- 
 tending it, and keeping it in repair. Evidently here is another 
 case where we would be better off without the condenser. 
 
 In a' well-designed engine, the power required to operate the 
 pumps may be less than one per cent of that developed by the 
 main engine, and is sometimes as high as three per cent. This 
 percentage or more of the steam supplied may be used according 
 as the pump is operated from the engine itself, or by an inde- 
 pendent cylinder more extravagant in the use of steam. 
 
 In order to understand one of the points that bears on the de- 
 sirability of the condenser in a special case, it is necessary to un- 
 
1 8 Effect of Cylinder Condensation. 
 
 derstand something of the cylinder condensation. When steam 
 contains just the number of heat units per pound given in the 
 tables, that is, just enough to evaporate it into steam, it is said to 
 be "saturated." This means that it is saturated with heat, not 
 with moisture. The term is apt to be misunderstood, and I have 
 frequently talked with engineers who could not get rid of the 
 idea that "saturated" steam must be soaking wet. The ordin- 
 ary steam that we get from boilers carries with it more or less 
 moisture, and steam is "commercially dry" when it has no more 
 than two per cent by weight of such moisture. If we apply heat 
 to such steam, and dry it out or evaporate the moisture, we shall 
 have "saturated" steam at the instant that all the moisture is 
 gone, and if we continue the heating so as to increase the tem- 
 perature above that due to the pressure, we shall have ' 'super- 
 heated" steam. 
 
 Now, unless steam is superheated, it cannot lose a particle of 
 heat, except by expansion, without a corresponding amount of 
 condensation. Steam' of 80 pounds gage (95 absolute) pressure 
 has a temperature of about 324 F. As it is expanded in the 
 cylinder after cut-off its temperature falls, and during the ex- 
 haust stroke the temperature is that due to the back pressure; 
 212 if the exhaust is against the atmosphere, 141. 6° with a con- 
 denser reducing the absolute back pressure to 3 pounds. As a 
 consequence, the cylinder and piston heads, the ports, and wall 
 of the cylinder, having been in contact with this cooler steam, 
 have had their temperature reduced and when the live steam en- 
 ters at the beginning of the stroke, it finds itself in contact with 
 surfaces comparatively chilly, and therefore has to part with 
 enough heat to raise these surfaces to its own temperature before 
 it can continue to exist as steam in contact with them. As a re- 
 sult, there is a large amount of condensation at the beginning of 
 the stroke, and this continues up to the point of cut-off. As the 
 steam commences to expand its temperature is reduced, the sur- 
 faces begin to give back the heat that has been expended upon 
 them, and the water resulting from the initial condensation com- 
 mences to boil under the diminished pressure, as did the water 
 when we cooled the flask in lecture I. Meantime, however, the 
 piston is uncovering new cylinder wall, which requires to be 
 heated, and this action will continue to a point where the temper- 
 
Effect q/ Cylinder Condensation. 19 
 
 ature which the wall has assumed equals the temperature of the 
 expanding steam. Beyond this point all the surfaces are hotter 
 than the steam and the re- evaporation is more rapid. Except on 
 very slow running engines, however, this re-evaporation during 
 the working stroke is not very extensive. In a good tight en- 
 gine at ordinary speeds the expansion line usually agrees very 
 well with the theoretical curve, commonly rising a little above it 
 at the later portion, showing that the re-evaporation but little 
 more than makes up for the condensation due to the conversion 
 of some of the heat units into work, and to radiation. In this 
 way the re-evaporation during the working stroke is a benefit, 
 but the greater part of the evaporation occurs during the exhaust 
 stroke, when the resulting steam can do no good, but is escap- 
 ing to the atmosphere, or the condenser. When the pressure is 
 reduced by the opening of the exhaust valve, the moisture in the 
 cylinder, being above the boiling point at the reduced pressure, 
 passes rapidly into steam, the heat for its continued evaporation 
 being furnished by the containing surfaces, and these containing 
 surfaces chilled by this abstraction of heat, must be heated 
 again on the following stroke. The wall never gets as cool as 
 the exhaust temperature, and probably never as hot as the in- 
 itial steam. The longer the time it is exposed to a temperature 
 lower than the initial and the lower the temperature of the ex- 
 haust, the greater will be its range of variation. Notice that 
 the surfaces must give up to the outgoing steam exactly as 
 much heat as they receive from the incoming steam. They cer- 
 tainly cannot give up any more, and if they did not give up as 
 much as they got, heat would accumulate and melt them down. 
 
 This subject of cylinder condensation is one of the most inter- 
 esting and important connected with steam engineering. Exper- 
 iments indicate that the loss from this action is rarely less than 
 20 per cent in simple unjacketed cylinders of ordinary automatic 
 engines, and it may be much more. The point I want to call 
 your attention to in connection with our present subject is that 
 the greater the difference between the initials and back pressures, 
 the hotter the steam the cooler the exhaust, the greater this ac- 
 tion and loss will be. Further, the earlier in the stroke the cut- 
 off occurs the greater the initial condensation, because of the 
 greater variation of temperature on the working stroke and the 
 
2o Diagram of Maximum Efficiency. 
 
 greater proportion of the time that the temperature of the steam 
 in the cylinder is below that of the steam chest. The condensa- 
 tion will also increase w T ith any increase in the proportion which 
 the area of the containing surface bears to the volume of steam 
 contained. 
 
 In an indicator diagram like Fig. 10, the space E B represents 
 the volume of the cylinder including clearance up to the point of 
 cut-off, while the shaded area is proportional to the work done. 
 The volume that must be filled with steam at each stroke will 
 bear the smallest proportion to the work done when as in Fig. 3 
 the cut-off is at such a point that expansion extends just to the 
 line of back pressure, making the diagram end in a point; and 
 compression extends just to initial pressure. The higher the in- 
 itial pressure and the lower the back pressure, the greater will be 
 the number of expansions used, and the greater the area of the 
 diagram compared with the ^ a b 
 volume up to cut-off. But 
 every engineer knows that, 
 notwithstanding the fact 
 that the steam accounted 
 for by the diagram per 
 horse-power would be the 
 least in amount under these . *N**r. 
 
 conditions, it would be very ^>' IO ' 
 
 poor economy to run an engine with so light a load. We might 
 continue the reduction of the diagram on these lines until the power 
 developed is barely sufficient to run the engine itself, in which case, 
 even if we got a very low rate of steam consumption per indicated 
 horse-power, the little useful power we would get would be very 
 expensive. As a matter of fact, however, we should use more 
 steam per indicated horse-power, for the gain by expansion falls 
 off rapidly as the number of expansions is increased, while the 
 loss by cylinder condensation increases at a rapid rate. Conse- 
 quently, there is a point where the loss from cylinder condensation 
 equals the gain from increased expansion, and any increase of ex- 
 pansion will result in a loss. The more power we can get out 
 of the cylinder the less proportion will the radiation and frictional 
 losses bear to the power delivered to the shafting, so that it is not 
 found economical in practice to cut off much earlier than one- 
 
• Independent and Direct Driven Condensers. 21 
 
 quarter stroke, in an ordinary single-cylinder non-condensing en- 
 gine without jackets; nor to expand much below the atmosphere 
 with a simple condensing engine. Obviously then, if an engine 
 is cutting off at one- fifth stroke, or earlier, there will be little 
 chance of increasing the economy by putting on a condenser. It 
 is possible to extend the point of cut-off without increasing the 
 mean effective pressure by lowering the boiler pressure, or throt- 
 tling it at the engine, but here the efficiency of the high pressure 
 steam is sacrificed, and it is still an open question how far it is 
 safe to go in this direction. I commend it to you as a subject for 
 profitable discussion, whether with an underloaded engine, con- 
 densing or not, it is profitable to reduce the initial pressure and 
 if so under what circumstances and to what extent. 
 
 Condensers may be divided into two general classes. Those 
 whose air pumps are driven by the main engine. 
 
 Those having their own independent motive power. 
 
 The first type includes belt and gear driven pumps as well as 
 those directly attached to the working parts of the engine itself. 
 The advantage claimed for them is that the power required to 
 drive them is generated in the large economical cylinder to much 
 better advantage that it can be in a small cylinder of a direct act- 
 ing pump, such as is usually used to operate the independent con- 
 denser. 
 
 On the other hand, the advocates of the independent conden- 
 ser claim that while the attached air pump is constrained to move 
 at the same speed as the main engine or a speed proportional 
 thereto, regardless of the amount of work it has to do, the inde- 
 pendent air pump can be run fast or slow according to the amount 
 of water passing, which varies with the load and the vacuum car- 
 ried. They further claim that the steam from the cylinders 
 which operate the pump can be used to heat the feed-water, thus 
 doing away with 1 he loss noted above, and that as practically all 
 the steam required to run the pump is thus utilized, it does not 
 matter if the pump is not so economical as the main engine. 
 Many of both types of condenser are used and each has its ad- 
 vocates. If one is very decidedly better than the other, it will 
 in time appear, and the fittest will survive or perhaps as in many 
 other cases it will be found that each is particularly adapted to 
 special circumstances. 
 
^2 
 
 The Vertical Air Pnmt>. 
 
 The amount of work done by an air pump depends not upon 
 the size of the piston, or the speed at which it runs, but upon the 
 amount of water and air that it forces out of the condenser 
 against the pressure of the atmosphere. In Fig. n, when the 
 bucket or piston rises, it leaves a vacuum behind it. Suppose 
 that the water line A B just reached the diaphragm CD when 
 the bucket was in its highest position, without lifting the valves. 
 Then when the bucket descended it would leave a vacuum above 
 it, and if no water is let in to raise the level A B the bucket will 
 continue to move up and down with a vacuum above and below 
 it, without doing any work or calling for any power except to 
 overcome its own friction. Now if we let a little water into the 
 chamber B, a corresponding 
 amount will pass through the 
 bucket on its downward stroke, 
 increasing the amount above 
 the bucket and the water line 
 A B will come in contact with 
 the diaphragm C D before the 
 upward stroke is completed, 
 lifting the valves in that dia- 
 phragm, andmaking the pump 
 complete the stroke against 
 the atmospheric pressure. /7^ 
 This is where the work of the 
 pump comes in, and this will 
 be dependent upon the quanti- 
 ty of water passed, for if we p^ II# 
 put in twice the amount of 
 
 water, the valves in C D will be open twice as long and the bucket 
 travel twice as far against the atmospheric pressure. Of course 
 there would be a saving, so far as friction is concerned, if the 
 pump could be run slowly enough to completely fill at each stroke, 
 instead of making several strokes to do an equivalent amount of 
 work, but it is not constantly working against a vacuum as many 
 suppose. 
 
 It is quite generally conceded that the vertical form of air 
 pump, although necessarily single acting, is preferable to the 
 double acting horizontal pump. This is due to the certainty of 
 
Sealed Glands — Surface Condensers 23 
 
 its action in taking water through the bucket valves, to the 
 quick and positive closure of the valves, to the facility with 
 which the water will collect in the bottom of the pump during 
 the up stroke ready for the bucket when it descends. The flow 
 is always in one direction, the water always lies on the valves 
 so as to keep them air tight, and very little clearance is necessary 
 between the foot and bucket valves and between the bucket and 
 head valves. The glands around the vertical rods can be cupped 
 and filled with water, to seal them against air leaks. It don't 
 hurt a vacuum any to have water leak into it, but a little air will 
 make a big difference, so that if you can keep water around a 
 place where air is likely to get in you will have a better vacuum. 
 I have heard of serious breaks in condensing apparatus being got- 
 ten over at sea by building a coffer dam around the fracture and 
 keeping it full of water. This kept it sealed against the atmos- 
 phere, and some water simply went through the crack instead of 
 through the injection valve. 
 
 Of course the air pump must be large enough to keep the con- 
 denser clear at times of maximum load or when the greatest 
 amount of water and air is to be handled. On the other hand, it 
 should not be too large so as to cause unnecessary loss by fric- 
 tion. The indications are that past practice has been too liberal 
 in this respect and that many engines have labored along with 
 cumbersome pumps where smaller sizes would have been ample. 
 It would appear, too, that good design lies in the direction of 
 short strokes and large diameters, for if we quarter the stroke of 
 a pump and double its diameter, it will have the same capacity, 
 the force required to overcome the friction will be exerted through 
 only one- quarter the space, and will be no more than twice what 
 it was before for the rubbing surface, the circumference of the 
 bucket has only been doubled, and in a vertical pump where the 
 bucket is always covered with water, this may be an easy fit. 
 The larger bucket also gives greater capacity for the valves and 
 the speed of the water through the larger passages thus afforded 
 is slower. 
 
 If you are interested in proportioning surface condensers, I ad- 
 vise you to read a paper on the subject by J. M. Whitham, page 
 417, Vol. IX., Trans. Amer. Soc. Mech. Engrs. In it he consid- 
 ers all the factors bearing on variable conditions and gives formu- 
 
2 4 
 
 The Injector Condenser. 
 
 lae which meet all conditions. For the average case, he gives a 
 very simple formula for the amount of cooling surface required. 
 
 Multiply the total number of pounds of steam conde?ised per 
 hour by ij and divide by 180. 
 
 This allows nearly one-tenth of a square foot of cooling surface 
 per pound of steam, which would not be a bad figure to bear in 
 mind. 
 
 A condenser may fail to work from a failure of the injection or 
 circulating water supply, in which case the steam will not be con- 
 densed, but will accumulate in the condenser, destroying the vac- 
 uum and heating the condenser 
 up. Relief valves which open 
 automatically to the atmos- 
 phere when the pressure in 
 the condenser exceeds that 
 outside are usually provided 
 to allow the engine to keep on 
 running non- condensing until 
 the trouble can be located and 
 remedied. Secondly, a con- 
 denser may fail to work on ac- 
 count of the failure of the air 
 pump to remove the water and 
 air as fast as it comes to the 
 condenser. Such a failure is 
 apt to result seriously, for if 
 there should be a vacuum in 
 the cylinder at such a time, 
 as there is likely to be by expansion in the low pressure cylinder 
 of a compound or triple expansion engine, or even in a single 
 cylinder engine when starting or stopping, or when lightly loaded, 
 the water will draw into it and result in a break down. For this 
 reason condensers are often, and should always be provided with 
 a device for automatically admitting air and breaking the vacuum 
 when the height of water in the condensing chamber exceeds a 
 safe limit, and care must be taken that nothing occurs to slow 
 down the air pump if indirectly connected or independent. 
 
 You remember the experiment we performed with the long 
 tube of mercury. The action would be just the same with water 
 
 Fisr. 12. 
 
The Injector Condenser. 
 
 25 
 
 RELIEF VALVE 
 
 enly it would take a longer column of water to balance the pres- 
 sure of the atmosphere. In Fig. 12, if the tank were originally 
 full of water, the water would run out through the pipe until the 
 column is just sufficient to balance the pressure of the atmos- 
 phere, which will be 34 feet more or less according to the tem- 
 perature of the water and the height of the barometer. If, then, 
 we have the pipe over 34 feet long, water will run out of the 
 chamber by its own weight against the atmospheric pressure, 
 leaving a vacuum in the chamber. If we let steam and cool 
 water together into such a chamber, the steam would be con- 
 densed, the water would flow out without 
 the necessity of a pump, and the vacuum 
 would be maintained without the bother 
 and expense of pumping the water out. 
 There is one fatal objection to the opera- 
 tion of this ideal scheme. We have seen 
 that the steam and the injection water 
 bring into the condenser more or less air 
 to say nothing of that which steals in 
 through leakage. *As the air would not 
 fall out by gravity, it would gradually ca- 
 cumulate and destroy the vacuum. This 
 objection is very ingeniously and simply 
 gotten over in the injector or ejector con- 
 denser, shown in Fig. 13. The exhaust 
 steam enters through the nozzle A. The 
 injection water surrounds this nozzle and 
 issues downward through the annular 
 space between the nozzle and the main 
 casting. The steam meeting the water is 
 condensed, and by virtue of its weight and of the momentum which 
 it has acquired in flowing into the vacuum the resulting water 
 continues downward, its velocity being further increased, and the 
 column solidified by the contraction of the nozzle shown. The air 
 is in this way carried along with the water and it is impossible 
 for it to get back against the rapidly flowing steam in the con- 
 tracted neck. The condenser will lift its own water twenty feet 
 or so. When water can be had under sufficient head to thus feed 
 itself into the system, and the hot- well can at the same time be 
 
26 Cooling Towers. Co?idensi?ig by Evaporatioii. 
 
 so situated as to drain itself, it makes a remarkably simple and 
 efficient arrangement. In case the elevation is so great that a 
 pump has to be used to force the injection, the pump has to do 
 less work than the ordinary air pump, and its exhaust can be 
 used to heat the feed water. 
 
 Except under exceptional circumstances, the nature of which 
 we have tried to indicate, the gain by the use of a condenser is so 
 great that their use is very general in plants where water can be 
 had for condensing purposes, and it is an important point for con- 
 sideration in locating a plant, whether or not a supply of suitable 
 condensing water will be available. In large cities where water 
 must be bought at a considerable cost, plants are run non- con- 
 densing at a great sacrifice of steam efficiency, because it would 
 be out of the question to buy water for injection. Considerable 
 has been done in the way of cooling water off after it has passed 
 through the condenser, and using it over and over again. This 
 is done by letting it trickle over a series of pans on the roof, or 
 letting it fall in a shower through a shaft through which a cur- 
 rent of air is circulated. 
 
 In this connection, there has recently appeared on the market, 
 an apparatus, which appears to promise well. You know as much 
 heat must be taken out of a pound of steam to reduce it to water 
 of a given temperature, as would have to be put into the water to 
 make it into steam from that temperature. Suppose the steam 
 from an engine cylinder is discharged through a series of pipes 
 upon the outside of which cold water is sprayed. Part of the 
 water, as it strikes the heated surface, will be evaporated and es- 
 cape into the atmosphere as vapor, but for every pound of water 
 so evaporated a pound of steam is condensed, and can be used as 
 boiler feed. Thus, instead of using the city water for boiler feed, 
 we use it to spray the condenser, and use the condensed steam 
 over and over in the boilers, and if, as it appears, and as the mak- 
 ers of the apparatus assure us, it takes no more water in one 
 case than in the other, we are ahead whatever net benefit we can 
 get out of the vacuum. 
 
 It is a mistake to strain for too high a vacuum. Of course 
 every particle that you can save by keeping things free from air 
 leakage is so much pure gain. What I mean is don't crowd your 
 circulating pump or open your injection too wide just to get the 
 
Situation of Pump. Lifting Valves. 27 
 
 last fraction of an inch of vacuum. The amount of water to be 
 handled to get an additional half inch at the lower end of the 
 gage is excessive, the temperature of your feed is reduced, and 
 while it may mean less pounds of steam per hour per horse- power 
 for the main engine, it is likely to mean more dollars per year 
 per useful horse-power delivered. If you do not use the hot-well 
 water for boiler feed, or if you have methods by which this may- 
 be heated, that would allow you to run a lower hot- well tempera- 
 ture to advantage. Suppose, for instance, you have an econo- 
 mizer of ample capacity, heating the water with the waste of the 
 uptake, then it would pay you to run a higher degree of vacuum, 
 for if your economizer is ample, it will deliver the water to the 
 boiler at about the same temperature whether it comes to it at 
 100 or 130, and, so long as you do not make your pumps do as 
 much extra work as the extra vacuum amounts to, you are 
 ahead. When cold water is used for feed or when there is a 
 very considerable difference between the hot- well and exhaust 
 steam temperatures, and the hot- well water is used for feed, the 
 water may be passed through a heater placed between the engine 
 and the condenser. The exhaust will have a temperature of 
 about 120 and will impart considerable heat to the feed, leaving 
 so much less for the condenser to do. 
 
 You will understand, of course, from what has been said of the 
 nature of a vacuum and of the nature of pumping that no pump, 
 however powerful, can lift water out of the condenser by suc- 
 tion because the atmosphere cannot act upon the water to force 
 it up to the pump. The pump must, therefore, be situated be- 
 low the condenser, so that the water can fall into it by its own 
 weight or head. Further, there must be no chance for any ac- 
 cumulation of air or the pump will get air bound and simply 
 work back and forth without taking any water. 
 
 A common annoyance connected with the running of an air 
 pump is the hammering or clattering of the discharge valves, due 
 to the variations in pressure as the air and water are discharging. 
 This can be avoided by connecting a small pipe with a valve into 
 the passage leading from the water cylinder to the delivery valve, 
 and admitting a small quantity of air, the amount to be admitted 
 being only sufficient to overcome the hammering. This air can- 
 not vitiate the vacuum in the condenser, as it aids the water in 
 keeping the inlet or foot- valve closed. The pipe should extend 
 to an elevation greater than the hot-well for otherwise the water 
 and the air will discharge from it on the down stroke of the 
 bucket.* 
 
 ^Constructive Steam Engineering, J. M. Whitham, p. 464. 
 
THE JET CONDENSER. 
 
 In Fig. i we have a vessel filled with steam at atmospheric 
 pressure. Attached to it is a U-tube filled with mercury, open to 
 the atmosphere at the outer 
 end. As long as the inside 
 and outside pressures are 
 equal, the mercury will be at 
 the same level in both legs of 
 the tube, as shown. If we 
 inject a spray of cold water in- 
 to the vessel through pipe W, 
 the steam will be condensed 
 and will fall to the bottom, 
 occupying only the small 
 space below the dotted line 
 AB in Fig. 2. The space 
 above the dotted line will now 
 
 be empty, or, in other 
 words, a vacuum, and since 
 the pressure on the inside is 
 removed, the mercury will 
 rise in one leg of the tube 
 as shown. If we continue 
 to supply steam and con- 
 densing water to the vessel 
 and draw out the condensed 
 steam and water as fast as 
 it accumulates, we can main- 
 tain a constant vacuum in the vessel. This was the principle 
 upon which the early mining pumps were operated. The piston 
 
Arrangement of Jet Condenser. 
 
 29 
 
 was drawn to the top of its stroke by the descending pump 
 plunger; steam at atmospheric pressure was admitted under the 
 piston and condensed by a spray or jet of water, thus creating a 
 vacuum. The pressure of the atmosphere then forced the piston 
 down, raising the pump plunger at the other end of the beam. 
 
 STEAM FROM BOILER OR 
 HIGH PRESSURE CYLINDER 
 
 The same thing is done on a larger scale and in a more scien- 
 tific manner by the jet condensing apparatus of today. 
 
 An entire apparatus of this type including all pipes and valves, 
 and connected to an engine cylinder, is shown in cross-section by 
 
30 Types of Jet Condensers. 
 
 Fig. 3. The engine piston is moving to the left, and the exhaust 
 steam is passing out through the lower left-hand port into the 
 exhaust pipe and from there into the bottle-shaped condenser. 
 As it enters the condenser it meets a spray of cold water issuing 
 from the injection pipe around the edges of the cone S; this spray 
 condenses the steam and the intermingled steam and water pass 
 down into the lower part of the condenser and the suction cham- 
 ber of the air pump. This leaves a vacuum in the condenser and 
 exhaust pipe and the engine cylinder up to the piston face. 
 When the air pump bucket starts on its upward stroke, the 
 mingled air and water pass by gravity up through the foot valves 
 of the air pump. When the air pump bucket descends, the water 
 and air pass up through the bucket valves to the upper side of 
 the bucket or plunger. The next upward stroke of the bucket 
 forces the water out through the head valves of the pump into 
 the discharge pipe, at the same time allowing more water and air 
 from the condenser to pass up through the foot valves into the 
 lower part of the air cylinder. This action is continuous and the 
 air-pump speed must be regulated to handle the condensed steam, 
 the water required to condense it and the air brought in by the 
 water. 
 
 L,et us consider some of the general features of the jet conden- 
 ser, and particularly the apparatus shown. 
 
 First among these is the fact that the injection or condensing 
 water and the condensed steam are mixed together. If the con- 
 densing water is pure the air pump discharge is suitable for boiler 
 feed, but if the condensing water is impure, acidulous or salt, it 
 is evident that the water discharged from the air pump is unsuit- 
 able for boiler use. Second, there is to be considered the type of 
 air pump and the means by which it is driven. This pump may 
 be of the horizontal or vertical type, single cylinder double acting, 
 dDuble or twin cylinder single acting or duplex; it may be inde- 
 pendently steam driven, as in Fig. 3, or it may be driven by a 
 belt from the main engine or shafting or by an electric motor. 
 The independent steam driven type has the advantage of being 
 absolutely independent of the main engine; it may be started be- 
 fore and stopped after the main engine, thus establishing a vac- 
 uum before the load is thrown on the engine and draining the 
 cylinder and pipes of the water of condensation and leakage. It 
 
Automatic Vacuum Bicakers and Relief Valves. 31 
 
 may be run at any speed within its limits, keeping the vacuum 
 constant under changes of load; it may also be placed at any con- 
 venient point near the engine. On the other hand, it is more ex- 
 pensive to operate than the belt or electrically driven type, as the 
 latter obtain their power at the same cost per horse-power as that 
 of the large units. We will not discuss here the relative econ- 
 omy of the different types. Another point of importance is the 
 possibility of damage or inconvenience through the failure of the 
 condensing apparatus or the improper arrangement of the con- 
 necting pipes. In case the air pump fails to operate or the in- 
 jection pipe becomes clogged, the engine must be shut down un- 
 less it is provided with another passage for the exhaust. The 
 usual method is to provide an atmospheric exhaust outlet, which 
 will allow the engine to exhaust into the atmosphere. As shown 
 in Fig. 3, this outlet is provided with an automatic relief valve A. 
 This is so arranged that when there is a vacuum in the exhaust 
 pipe between the engine and condenser the atmospheric pressure 
 on the outer side of the valve keeps it closed. If the air pump 
 becomes inoperative, the pressure accumulates in the exhaust 
 pipe and condenser and forces the valve open, allowing the engine 
 to exhaust freely into the atmosphere. When the vacuum is re- 
 established and the inside pressure falls below that of the atmos- 
 phere, the valve closes automatically. This valve may be a 
 special swing check or any one of a number of other special 
 valves made for the purpose. The gate valve B is intended for 
 use in case of repairs to the condenser; it may be closed tightly 
 and the automatic valve A locked open, when the condenser or 
 air pump may be repaired without interference from the hot ex- 
 haust steam. In case the condenser and air pump are connected 
 to injection and discharge mains common to other condensers the 
 gate valves C and D are necessary in the event of repairs to the 
 condenser or pump; the valve C is, however, primarily intended 
 to regulate the supply of injection water as will be mentioned 
 later. 
 
 Another source of trouble in jet condensing engines is the pos- 
 sibility of getting water into the engine cylinder and so wrecking 
 it. Suppose the air pump to be running but slowly, or to stop 
 entirely, so that it will not draw out the injection water as fast as 
 it runs into the condenser. Eventually the water will flood the 
 
32 
 
 Types of Vacuum Breakers. 
 
 condenser and pipes, enter the cylinder and wreck it. To render 
 this impossible, two methods are adopted: one is the application 
 of a vacuum-breaking device to the condenser; the other is to so 
 arrange the spray cone and condenser neck that an accumulation 
 of water will reduce the surface of the spray and break the vac- 
 uum. 
 
 Fig. 4 shows a patented vacuum-breaker furnished on all Geo. 
 F. Blake & Knowles' condensers. Its action will be understood 
 from the cut. When the 
 water rises in the condenser 
 to the level AB, it lifts the 
 float F, which in turn lifts 
 the air valve V from its 
 seat, admitting air to the 
 exhaust pipe and engine 
 cylinder through the pipe 
 P, thus breaking the vac- 
 uum. This, of course, 
 equalizes the inside and 
 outside pressures, and pre- 
 vents any more water from 
 flowing into the condenser. 
 The engine exhaust will 
 then accumulate until it 
 acquires sufficient pressure 
 to lift the valve A, Fig. 3, 
 and the engine will ex- 
 haust into the atmosphere. 
 
 Fig. 5 shows the arrange- 
 ment of condenser neck and 
 spray cone used upon the 
 Worthington condensers to 
 accomplish the same result. 
 In this case the water is sprayed downward, and as the con- 
 denser neck is quite small, the rapid condensation is due only 
 to the large surface exposed by the spraying water. Owing 
 10 the small size of the condenser, any accumulation of water rap- 
 idly diminishes the condensing surface until the spray itself is 
 submerged, leaving only the small annular ring of water at A B 
 
How to Start and Stop a Condensing Engine. 
 
 33 
 
 . 
 
 
 
 
 2^- 
 
 EXHAUST 
 STEAM 
 
 7 /I 
 
 ^_\%-~S( 
 
 -B 
 
 3 RAY CONE 
 
 to act on the large volume of steam from the engine. The sur- 
 face of this ring is far too small to condense the steam and the 
 pressure immediately accumulates and either the valve A, Fig. 
 3 opens, allowing the engine to run non-condensing or the ex- 
 haust steam blows out through the injection pipe and pump 
 valves. 
 
 Again, the engine itself may draw water up into the low pres- 
 sure cylinder. Suppose a compound engine having a low pres- 
 sure cylinder of 4 times the area of the high pressure. In start- 
 ing up or shutting down the engine 
 the throttle is barely cracked, as 
 usual, admitting throttled steam of, 
 say, 20 pounds absolute pressure 
 for the full stroke. At the end of 
 the stroke this seam will be admit- 
 ted to the low pressure cylinder, 
 where it expands to 4 times its 
 volume, or to about 5 pounds ab- 
 solute pressure. This is equivalent 
 to a vacuum of about 20 inches. 
 Now suppose the air pump to be 
 almost or entirely stopped and the 
 injection valve to be open as usual. 
 Then when the low pressure piston 
 starts on its return stroke, the ex- 
 haust valve opens, connecting the 
 cylinder under 20 inches of vacuum 
 with the exhaust pipe and conden- 
 ser, also under a vacuum; the at- 
 /w.jv.r. mospheric pressure will continue 
 
 to force water up into the condenser, and, if the air pump 
 cannot remove it, up into the engine cylinder. This would be 
 prevented by the vacuum-breaking device shown in Fig. 4. 
 This brings us to the proper method of starting and stopping an 
 engine with an independent condensing apparatus. To start the 
 apparatus, proceed as follows: Open slightly the injection valve 
 C and start up the air pump to its normal speed. This produces 
 a vacuum in the pipes and condenser, drains them of all water, 
 and causes the injection water to flow into the condenser. When 
 
 Fig. 5 
 
 HYi 
 
34 Starting a Balking hijection. 
 
 the vacuum is established, as shown by the gage, open the throt- 
 tle and turn the engine over slowly, warming it up. Then bring 
 the engine up to speed, throw on the load and regulate the 
 amount of injection water by the valve C. The wheel on the 
 top of the condenser is used only for regulating the thickness of 
 the spray and has nothing to do with the supply of injection 
 water. 
 
 The speed of the air pump and the amount of injection water 
 must be regulated according to the load on the engine and the 
 amount of vacuum desired. 
 
 When several condensers are connected to a common injection 
 main, it sometimes happens that starting up the air pump of an idle 
 condenser will fail to bring water in through the injection branch. 
 This is partly owing to the fact that the greater vacuum already 
 established in the other condenser draws the water away from the 
 condenser in question, but in a greater measure it is due to the fact 
 that a flow of water at a high velocity is aheady established to the 
 other condensers. This stream of water requires some force to 
 break its flow and to divert a portion of it into a branch pipe, just 
 as the stream of water from a hose nozzle will remain a smooth 
 rod of water for some distance from the end of the nozzle, or just 
 as the jet of water into an injector tube passes the spills or over- 
 flow holes without losing a drop of water through them. 
 
 In such event, recourse must be had to the forced injection or 
 priming pipe shown in Fig. 3. This forced injection takes its 
 supply from a source under a very slight head or pressure, such 
 as a surge tank slightly elevated or the city water supply. If the 
 water will not come to the condenser, allow the air pump to run, close 
 main injection valve C, open fully priming valve E, and admit 
 water until a vacuum is formed in the condenser; then open gradu- 
 ally injection valve Cand close priming valve E gradually, when 
 it will be found that the flow of water to the condenser is estab- 
 lished. When this forced injection does not overcome 
 the trouble entirely, it will usually be found that the injection 
 pipes are too small, making the velocity of flow too great. In 
 such cases, the velocity of flow should be decreased by increasing 
 the size of the injection main and branches. 
 
 When shutting down an engine with an independent condens- 
 
Stopping an ungine with an Independent Condenser. 35 
 
 ing apparatus, close the engine throttle first, and when the engine 
 has stopped, and not until then, close the injection valve C, and 
 lastly shut down the air pump. By shutting off the water supply 
 before the air pump is stopped, the water already in the con- 
 denser and pipes is pumped entirely out and there is no danger of 
 it getting into the engine cylinder. 
 
THE SURFACE CONDENSER. 
 
 Suppose that we have a cylindrical vessel arranged as in Fig. 
 6, with a pipe through the center, leaving an annular space out- 
 side of the pipe. If we fill the annular space with steam and run 
 a stream of cold water through the pipe, the steam will condense 
 upon the cold pipe surface and fall to the bottom of the vessel, 
 leaving a vacuum above it. If we draw off this condensed steam 
 
 and the air it brought in 
 with it, we can refill the 
 vessel with steam and, by 
 running more cold water 
 through the pipe, condense 
 this new steam; this opera- 
 tion can be continued in- 
 definitely and a constant 
 vacuum maintained in the 
 vessel. In this case, we see 
 that the exhauster draws 
 out only the condensed 
 steam and entrained air, 
 the cooling water being 
 kept entirely separate. 
 
 In the jet condensing arrangement shown in Figs, i and 2, it 
 is plain that the condensing water flows into the vessel on account 
 of the vacuum therein; while in this case the part of the vessel 
 which is under a vacuum is, as we said above, entirely separate 
 from the condensing water, making it necessary to force the water 
 through the pipe by some other means 
 
 This is exactly the manner in which the surface condenser 
 operates. 
 
 Fig. 7 shows a sectional view of a complete surface condenser 
 and pumps. 
 
 o 
 
 Power. N.T. 
 
37 
 
38 Description of Surface Condenser. 
 
 The exhaust steam from the engine enters the condenser 
 through the elbow on top; it then expands and fills the space out- 
 side of and between the condenser tubes. The circulating pump 
 shown at the left draws its water by "suction" from any con- 
 venient source and circulates it through the tubes, keeping them 
 cold. The exhaust steam is condensed by contact with these cold 
 surfaces and falls to the bottom of the condenser. It is then 
 drawn off by the air pump shown at the right, and is usually dis- 
 charged into a hot well. The drawing shows clearly that the 
 condensed steam, being outside the tubes, is kept entirely separate 
 from the condensing water, which is forced through, the tubes. 
 Evidently then, the condensed steam discharged by the air pump 
 may be used over again in the boilers, even if the cooling water is 
 unfit for use, the only objection to this being the oil brought down 
 by it from the engine cylinder and steam chest. There are several 
 more or less satisfactory methods of extracting this oil or grease 
 from the water; a discussion of their merits is beyond the province 
 of this article. The condensing water is handled by a separate 
 pump and does not flow into the condenser, as in the case of a jet- 
 condensing apparatus; it may be salt or impure, and unless warm 
 water is required for some outside purpose it is discharged to 
 waste. 
 
 It is thus seen that a surface condensing apparatus requires two 
 pumps of comparatively small size as against one large pump for 
 the jet condenser. It is considerably more expensive than the 
 latter, and is seldom used except where it is desirable to return 
 the condensed steam to the boilers. 
 
 The possibilities of trouble from it are less than in the jet con- 
 denser. There is no way in which the condensing water can get 
 into the engine cylinder; while the condensed steam might, under 
 certain conditions of air pump operation, accumulate until it 
 reached the top of the condenser, it could not get into the 
 cylinder, for the condensing surface would be entirely submerged 
 and the accumulated pressure would force open the automatic at- 
 mospheric relief valve and allow the engine to exhaust into the 
 atmosphere. 
 
 There is the same need of an atmospheric exhaust outlet as in 
 the case of the jet condenser and for precisely the same reason. 
 
 The piping between the engine, the elbow on the condenser, and 
 
Types of Air Pumps. 
 
 39 
 
 the atmospheric exhaust should be the same as in Fig. 3. In (he 
 type of apparatus shown, the condenser is directly attached to the 
 pump or pumps. This is not at all necessary; the air or circulat- 
 ing pump or both may be placed at any convenient point and con- 
 nected with the condenser by pipes. The air pump, however, 
 should be placed below the condenser, so that the condensed steam 
 may go to it by gravity. Nor is it necessary to use the type of 
 pump shown by the drawings. The pumps may be horizontal or 
 vertical; of the single or double-acting single- cylinder type; the 
 single-acting twin-cylinder type; or the duplex type. Fig. 8 
 shows a horizontal double-acting cylinder air pump, independently 
 
 £=0 
 
 Fig. 8. 
 
 steam-driven, which is frequently used with both jet and surface 
 condensers. The condenser outlet is connected with the suction 
 inlet of the pump, and its operation is the same as any double-act- 
 ing pump. 
 
 Centrifugal pumps are frequently used as circulating pumps, 
 and various combinations of pumps and condensers are made. 
 
 Fig. 9 shows a surface condenser equipped with 3-cylinder ver- 
 tical reciprocating air pumps and centrifugal circulating pumps, 
 both pumps being driven by electric motors. The details of the 
 condenser itself vary: for instance, a jet condenser is frequently 
 box-shaped instead of bottle or cone-shaped as in Fig. 3; a sur- 
 face condenser may be rectangular in cross section instead of 
 cylindrical, as in Fig. 7; the steam may be inside and the water 
 outside the tubes of a surface condenser, instead of as shown in 
 Fig. 7; etc., etc. The principle is the same, however, in all ar- 
 
4 o 
 
 Motor- Driven Air and Circulating Pumps. 
 
 rangements; in a jet -condensing apparatus the steam is condensed 
 by contact with a jet or spray of cold water and the air pump 
 handles the condensed steam, the condensing water and the air 
 entrained in both; in a surface condensing apparatus the steam is 
 condensed by contact with a cold surface and the air pump handles 
 
 EXHAUST INLET 
 
 the condensed steam and the air, while the circulating pump 
 handles the condensing or circulating water alone. 
 
THE INJECTOR OR SIPHON CONDENSER. 
 
 Fig. 10 is a small ^cale reproduction of the jet condensing ap- 
 paratus described in Fig. 3. It will be seen that with the arrang- 
 ments shown, an air pump is required to pump out the condensed 
 steam, the condensing water and the air brought in by both. 
 
 If the hot well were lowered to a point about 34 feet below the 
 condenser, as shown by the 
 dotted lines, it will be seen 
 that an air pump is not re- 
 quired to remove the con- 
 densed steam and the water. 
 This will be plain if it is 
 remembered that a perfect 
 vacuum of 30 inches in the 
 engine exhaust pipe will 
 not support a column of 
 water in the discharge pipe 
 more than 34 feet high; so 
 that if any water is sup- 
 plied to the condenser in 
 excess of this 34- foot col- 
 umn it will pass through 
 the condenser and out of the 
 discharge pipe without the aid of a pump. Now, if the neck of 
 the condenser be contracted, as in Fig. 11, the velocity of this 
 falling water will be greatly increased, and the water will carry 
 out with it not only the condensed steam but the air, leaving a 
 vacuum in the exhaust pipe. 
 
 This is the principle of the injector or siphon condenser, one 
 type of which, the Bulkley, is shown in cross-section in Fig. 12. 
 As will be seen from the figure, it is not necessary to place the 
 
42 
 
 Principle of Injector Condenser. 
 
 O 
 
 O 
 
 o 
 
 o 
 
 £ 
 
 condenser below the engine, as in Figs. 10 and n. All that is 
 required is to have the column of water between the condenser and 
 the hot well as great or greater than the vacuum will support, so 
 that the constant supply of condensing water will produce a con- 
 tinuous downward flow. In the arrangement shown the hot well 
 is a little below and the condenser is above, the engine level, an 
 ordinary tank pump being used to elevate the condensing water. 
 The exhaust steam enters the top of the condenser and passes 
 through the inner cone or nozzle C. The condensing water enters 
 
 the condenser at the side and 
 passes downward around the ex- 
 haust nozzle in a thin conical 
 film. The exhaust steam is con- 
 densed within this hollow cone of 
 falling water, and the condensed 
 steam and the condensing water 
 then fall vertically through the 
 condenser, and discharge pipe. 
 In passing through the neck of 
 the condenser the water acquires 
 sufficient velocity to draw out 
 with it the entrained air, leaving 
 a vacuum in the exhaust pipe 
 and engine cylinder. The lower 
 end of the discharge pipe is 
 sealed by the water in the hot 
 well. It is necessary to provide 
 a large condensing surface, as 
 well as a high velocity for the in- 
 jection water; in most condensers 
 of this type this is provided for by 
 bringing the exhaust steam in 
 through the cone or nozzle C, and 
 the injection water in through the annular space outside the cone. 
 This forces the condensing water to take the shape of a hollow 
 cone into which the exhaust steam is discharged. 
 
 In the Knowles Spirojector condenser, which is otherwise simi- 
 lar to the Bulkley, the cone C has cast on its face vanes which 
 compel the injection water to assume a spiral or whirling motion 
 as it passes through the condenser to the discharge. 
 
 Fig. 11 
 
 HOT WELL 
 
Arrangement of Injector Coridensor. 
 
 43 
 
 In Fig. 12 a pump is shown for lifting the condensing water; if 
 the level of the injection water supply is not more than, say, 20 
 
 RELIEF VALVE 
 
 feet below the condenser inlet, the condenser will siphon the water 
 over as soon as a vacuum is formed in it and the water pump may 
 
44 
 
 The Injection Water Supply. 
 
 be dispensed with. As 20 feet is about the limit to which water 
 may be continuously lifted by the siphoning action, it follows 
 that when the water supply is more than 20 feet below the con- 
 denser a pump must be used. The arrangement with a pump 
 shown in Fig. 1 2 is sometimes modified by the insertion of a tank 
 (shown in dotted lines) at about the lower limit of the siphon. 
 This is convenient when a single-acting or single-cylinder tank 
 pump is used to lift the water; such a pump gives a more or less 
 intermittent flow, whereas a practically constant flow is required 
 by the condenser. In the tank arrangement, the pump discharges 
 intermittently into the tank and the condenser siphons continu- 
 ously from the tank. Fig. 
 13 shows the arrangement 
 of condenser and pipes for a 
 siphoning apparatus, when 
 no pump is used. In this 
 figure there is shown a 
 cross connection at the sup- 
 ply level between the injec- 
 tion and discharge pipes. 
 As we said before, the vac- 
 uum must be formed in the 
 condenser before it will 
 siphon water; by opening 
 the starting valve ^S water 
 is admitted to the discharge 
 pipe, and in falling through 
 the pipe it draws the air out 
 with it, forming enough 
 vacuum in the upper pipes 
 and condenser to draft the injection water up to the condenser. The 
 starting valve should then be closed and the water supply should 
 be regulated by valve J. When the injection supply is at the ex- 
 treme lower limit of the siphon, say 20 feet below the condenser, 
 this arrangement of starting valve is not always satisfactory; in 
 such cases the cross connection may be omitted and a small prim- 
 ing pipe P, shown in dotted lines in Fig. 13, may be run from the 
 boiler feed pump discharge to the condenser inlet. As soon as 
 the injection water appears the valve/ may be closed and the feed 
 
Adva?itagcs of the Type. 
 
 45 
 
 RELIEF VALVE 
 
 pump may resume its usual duty. When a pump is used to ele- 
 vate the water, the starting valve or priming pipe and the injec- 
 tion valve/ are of course omitted, as the vacuum is formed by 
 forcing water directly into the condenser, and the water supply 
 is regulated by the pump speed. 
 
 This type of condenser is suitable for many locations, and if 
 properly made and connected will maintain a good vacuum. It is 
 economical in operation and has no moving parts to wear or to get 
 out of order. There is no way in which water can get into the 
 engine cylinder unless it is 
 allowed to accumulate in the 
 pocket formed by the ex- 
 haust pipe, and not even 
 then unless atmospheric 
 pressure is admitted to the 
 exhaust pipes through the 
 uncovering of the water 
 supply or discharge pipes. 
 A drain pipe placed as 
 shown in Fig. 12 will serve 
 to drain out the exhaust 
 pipe before the engine is 
 started and removes all 
 danger from this source. 
 Pumping action of the low 
 pressure cylinder cannot 
 draw water up from the hot 
 well on account of the 
 height, and water drawn 
 up from the injection supply would fall into the discharge pipe 
 and not into the exhaust pipe, by reason of the construction. 
 Another condenser of this type, but differing slightly from the 
 above in detail, is the Baragwanath water jacket condenser shown 
 in Fig. 14. In this condenser, as in the others, the exhaust en- 
 ters at the top and the injection at the side, and the exhaust noz- 
 zle is surrounded by cold water. The water chamber is larger 
 than in the others, and the shell of the condenser is prolonged in- 
 side the water chamber, forming an inverted cone, into the end of 
 which the condensing nozzle C projects. This nozzle is adjustable 
 
46 Automatic Relief Valve. 
 
 by means of the spindle shown and can be set to admit precisely 
 the right amount of water. 
 
 Each of the three condensers mentioned herein, i. e., the Bulk- 
 ley injector, the Knowles Spirojector and the Baragwanath water 
 jacket, is supplied with an automatic atmospheric relief valve 
 similar to that shown in Fig. 13; this valve discharges directly 
 into the atmosphere, so that when the top of the condenser is in- 
 side the building it is necessary to use a relief valve in the pipe 
 line and to carry the atmospheric exhaust pipe out of doors. This 
 valve may be of the swinging check type shown in Fig. 3, or any 
 one of several well-known types. The injection water may be 
 supplied under a head or a pump of either the reciprocating, the 
 rotary or the centrifugal type may be used. The head against 
 which these pumps work is evidently quite small, since the 
 vacuum in the condenser will take care of the upper 18 or 20 
 feet of the lift. 
 
THE EXHAUST STEAM INDUCTION CONDENSER. 
 
 The operation of this condenser is based upon the same principle 
 as that of the steam injector. As most of our readers know, the 
 operation of the injector is as follows: A jet of steam enters 
 through the steam tube at a high velocity and induces the air in 
 the suction pipe and injector body to pass out with it; this leaves 
 a vacuum and allows the atmospheric pressure to force in water. 
 The steam is condensed by this water and the velocity of the 
 steam is imparted to the water; then the energy in the moving 
 column of water is sufficient to overcome the pipe friction, lift 
 the check valve and force the water into the boiler against the 
 pressure. 
 
 An inspection of Fig. 15 shows that this is exactly the opera- 
 tion of the induction condenser. The exhaust steam enters 
 through the valve E and passes through the inclined perforations 
 into the central tube T, as shown by the arrows. Owing to the 
 velocity of its movement the air in the condenser and the injec- 
 tion pipe is drawn out with it, and the atmospheric pressure on 
 the injection supply forces the condensing water up through the 
 pipe and into the tube T as shown. The exhaust steam is con- 
 densed by this water and a vacuum is left in the condenser 
 and exhaust pipe. The original velocity with which the water 
 entered the condenser and the added velocity due to the 
 exhaust steam enable the mingled steam and water to over- 
 come the atmospheric pressure on the discharge end and 
 pass out into the hot well, just as the water from the injector 
 overcomes the resistance due to friction and pressure and passes 
 into the boiler. From this we see that the velocity of the dis- 
 charge is sufficient to draw out the air and to get rid of the con- 
 densing water and condensed steam; so that no air pump is re- 
 quired as in the case of a jet or surface condenser, nor a 34-foot 
 "tail" column, as in the injector or siphon condenser. 
 
4 8 
 
 Arrajigement of Induction Co?ide?iser. 
 
 The condenser shown in Fig. 15, however, has its limits of 
 operation. We have just seen that the operation depends upon 
 the velocity of the discharge; it is plain that when the condenser 
 lifts its injection water, as shown in the figure, this velocity must be 
 almost wholly imparted by the exhaust steam. Then if the load 
 on the engine is variable or if the condenser is too large for the en- 
 gine, there will be times when the small amount of exhaust steam 
 
 QHI 
 
 Fig. 15. 
 
 furnished by the engine will not be enough to impart the required 
 velocity to the large volume of water and the condenser will not 
 operate satisfactorily. In other words, the volume of exhaust 
 steam must be, within limits, in proportion to the volume of 
 water which it keeps in motion, too little steam being unable to 
 induce the flow of water and too much steam affecting the vac- 
 uum. The minimum amount is that which will increase the 
 
Adjusting the Capacity. 
 
 49 
 
 temperature of the water at least 30 F. and the maximum 
 amount is that which will not cause a rise of more than 50 F. in 
 the water temperature. 
 
 In cases where the condenser takes its water under a head, as 
 shown by dotted lines in Fig. 15, this objection does not apply, 
 for then the velocity of the water is that due to the head and is 
 independent of the exhaust steam. 
 
 In order to guard against the trouble due to a varying amount 
 of exhaust steam, the con- 
 denser shown in Fig. 16 has 
 been devised. It is called 
 the adjustable capacity con- 
 denser in order to distin- 
 guish it from the fixed 
 capacity condenser shown 
 in Fig. 15. Both the con- 
 densers shown were design- 
 ed by Korting and are 
 identified with 1^. Schutte 
 in America. 
 
 The adjustable condenser 
 shown in Fig. 16 is provid- 
 ed with a movable ram R 
 inside the central water 
 tube and a sleeve £ out- 
 side the tube. The ram is 
 tapering and controls the 
 volume of water admitted 
 by increasing or diminish- 
 ing the annular space be- ***,&* 
 tween its surface and the inside of the tube; while the sleeve 5, 
 by covering more or fewer openings in the tube, governs the area 
 of the exhaust inlet and consequently the velocity of the exhaust 
 steam. The relative positions of the ram and the sleeve can be 
 regulated by the extension rod K, so that the machine can be 
 adjusted for almost any condition of load. In fact, the machine 
 may be adjusted to work satisfactorily at any point from j{ or 
 1-5 of its capacity to full capacity; this is particularly desirable, 
 
5<d Preventing Flooding. 
 
 as we have said, when the load is variable and the injection water 
 must be lifted. On the other hand, the range of the fixed ca- 
 pacity condenser is only from about one-half capacity to full ca- 
 pacity. For high suction lifts, the live steam jet or water pres- 
 sure jet/ is used to bring the water to the condenser, and an es- 
 cape is provided through the overflow valve O just as in the case 
 of the steam injector. This starting jet and overflow valve are 
 necessary only when starting, and may both be omitted when 
 the suction lift is very small or when water is supplied under a 
 head. It will be seen that in this condenser, as in the jet and 
 siphon condensers previously described, the condensed steam 
 and the condensing water are mixed together, so that the water 
 from the hot well can not be used for boiler feed unless the con- 
 densing water is pure. An inspection of Fig. 1 5 shows that an 
 atmospheric outlet must be provided for the exhaust, just as in the 
 cases of the jet, surface and siphon condensers. The figure shows 
 a special swing check valve for this purpose, while on the adjust- 
 able capacity condenser in Fig. 16 is shown the automatic valve 
 usually furnished with this type of condenser. 
 
 In this condenser there is no 34- foot tail column, and in case 
 the low pressure cylinder of the engine acts as a pump, water may 
 readily be drawn up into the engine. 
 
 This is prevented by the arrangement of the stop valve E, 
 through which the exhaust steam enters the condenser. The 
 valve itself is not fixed to the spindle, but is free to move verti- 
 cally within the limits set by the seat at the bottom and the collar 
 C on the spindle at the top. It thus allows steam to pass out 
 under it from the engine into the condenser, but acts as a check 
 valve against the passage of water in the opposite direction or 
 from the condenser to the engine. It may also be used as a stop 
 valve by lowering the spindle until the collar C locks the valve 
 to its seat. Since the seat of this valve is practically at the top 
 of the exhaust pipe, it is advisable to drip the pipe on the engine 
 side of the valve, as shown in Fig. 15, to prevent any accumula- 
 tion of condensation. This drip may be piped into the condenser 
 as shown, with a check valve arranged to prevent the return of 
 water from the condenser to the exhaust pipe. 
 
 The directions for starting or stopping au engine equipped with 
 either type of this condenser are very simple. It is always 
 
Stopping and Starting with an Induction Condenser. 51 
 
 desirable to start the condenser and form the vacuum before 
 starting the ermine, as we have mentioned in connection with the 
 other condensers. 
 
 To start the engine, proceed as follows: 
 
 When the condensing water is under a head, turn on the con- 
 densing water and when a vacuum is formed start up the engine. 
 When the condensing water must be lifted, open the steam or 
 pressure jet valve/, and as soon as this has lifted the water start 
 the engine. The operation of the condenser will begin as soon as 
 the engine exhaust reaches the condenser and when the vacuum 
 is formed the suction or lifting jet may be turned off. In shutting 
 down, stop the engine first, when the operation of the condenser 
 will cease if the condensing water is under a suction lift; if the 
 water supply is under a head, stop the engine first and then shut 
 the valve in the water supply pipe. 
 
52 
 
 CONDENSER CAPACITIES. 
 
 In column 4 of Table I are given the number of heat units 
 required to raise a pound of water from zero Fahrenheit to the 
 corresponding temperatures T in column 3. 
 
 In column 5 are given the numbers of so-called ' 'latent' ' heat 
 units L required to convert a pound of water at the corresponding 
 temperatures T into dry saturated steam of the same temperature, 
 the corresponding pressures being given in various units in columns 
 1 and 2. 
 
 Column 6 gives the total number of heat units H required to 
 raise a pound of water from zero F. to the corresponding temper- 
 ature and to convert it into steam of that temperature. It is the 
 sum of the corresponding values in columns 4 and 5. 
 
 For example, in a vacuum of 25 inches (column 1), wmich is 
 the same thing as an absolute pressure of 2.417 pounds to the 
 square inch (column 2), water vill boil at 133 degrees F. (column 
 3). It will take 133.21 heat units to raise a pound of water from 
 zero F. to this temperature (column 4), and 1,021.295 more heat 
 units (column 5) to evaporate the pound at that pressure and 
 temperature, making a total of 1,154.505 (column 6). 
 
 To make a pound of steam at an absolute pressure of 20 pounds 
 (column 2) from a pound of water at 1 io° would require 
 
 1,183.454—110.110 = 1,073.344 
 heat units, because the pound of water has already no. no heat 
 units in it (column 4) above what it would have at zero F. , and 
 there are in a pound of steam of 20 pounds pressure absolute 
 1,183.454 heat units above the number in a pound of water at 
 zero (column 6). 
 
 Condensation is the reverse of evaporation. If we wish to 
 
TABLE I 
 
 i a I 
 
 -PHYSICAL PROPERTIES OP SFBAJI. 
 
 3 14 15 I 
 
 
 
 
 Heat Required 
 
 to Convert a Pound of Water 
 
 Pressure 
 
 Temperature. 
 
 at Zero F. into Steam. 
 
 Vacuum 
 
 
 
 To Raise the 
 
 To Conr<jrt the 
 
 
 „ by 
 
 Absolute. 
 
 
 Temperature 
 
 Water at the 
 
 Total. 
 
 Gage. 
 
 
 to tho Boil- 
 
 Boiling Point 
 
 
 
 T 
 
 ing Point. 
 
 into Steam. 
 
 
 Inches 
 
 Lbs. per 
 
 
 h 
 
 L 
 
 H 
 
 Mercury. 
 
 .^q in. 
 
 Degrees F. 
 
 Heat Units. 
 
 Heat Units. 
 
 Heat Units. 
 
 29.74 
 
 .089 
 
 32 
 
 32 
 
 1091.700 
 
 1123.700 
 
 29.72 
 
 .100 
 
 35 
 
 35 
 
 1089.015 
 
 1124.615 
 
 29. G7 
 
 .122 
 
 40 
 
 40.001 
 
 1086.139 
 
 1126.140 
 
 29.6 J 
 
 .147 
 
 45 
 
 45.002 
 
 1082.661 
 
 1127.665 
 
 29.56 
 
 .170 
 
 50 
 
 50.003 
 
 1079.187 
 
 1129.190 
 
 29.49 
 
 .212 
 
 55 
 
 55.000 
 
 1075.709 
 
 1130.715 
 
 29.40 
 
 .254 
 
 GO 
 
 60.009 
 
 1072.231 
 
 1132.240 
 
 19.30 
 
 302 
 
 65 
 
 05.011 
 
 1068.751 
 
 1133.765 
 
 29.19 
 
 .359 
 
 70 
 
 70.020 
 
 10G5.270 
 
 1135.290 
 
 29 
 
 .425 
 
 75 
 
 75.027 
 
 1061.788 
 
 1136.815 
 
 28.90 
 
 .502 
 
 80 
 
 80.030 
 
 1058.304 
 
 1138.340 
 
 28.72 
 
 .590 
 
 85 
 
 85.045 
 
 1054.8 
 
 1139.&65 
 
 28.51 
 
 .692 
 
 90 
 
 90.055 
 
 1051.355 
 
 ) 141. 390 
 
 23.27 
 
 .809 
 
 95 
 
 95.0G5 
 
 1047.850 
 
 1142.915 
 
 28 
 
 .943 
 
 100 
 
 100.080 
 
 1044.300 
 
 1144.440 
 
 27 85 
 
 1. 
 
 102 
 
 102.086 
 
 1042.9C4 
 
 1145.050 
 
 27.09 
 
 1.094 
 
 105 
 
 105.095 
 
 1040.870 
 
 1145.965 
 
 27.34 
 
 1.205 
 
 110 
 
 110.110 
 
 1037.380 
 
 1147.490 
 
 27 
 
 1.435 
 
 114.34 
 
 114.470 
 
 1034.344 
 
 1148.814 
 
 26.95 
 
 1.462 
 
 115 
 
 115.129 
 
 1033.880 
 
 1149.015 
 
 26.50 
 
 1.682 
 
 120 
 
 120.149 
 
 1030.391 
 
 1150. 54J 
 
 26 
 
 1.931 
 
 125 
 
 125.169 
 
 1026.896 
 
 1152.0b5 
 
 25.85 
 
 2. 
 
 126.266 
 
 126.440 
 
 1026.010 
 
 1152.450 
 
 25.42 
 
 2.213 
 
 130 
 
 130.192 
 
 1023.389 
 
 1153.590 
 
 25 
 
 2.417 
 
 i:53 
 
 133.21 
 
 1021.295 
 
 1154.505 
 
 24.79 
 
 2.520 
 
 135 
 
 135.217 
 
 1019.898 
 
 1155.115 
 
 24. GO 
 
 2.876 
 
 140 
 
 140.245 
 
 1016.305 
 
 1156.640 
 
 24 
 
 2.9 
 
 141.293 
 
 141 .543 
 
 1015.491 
 
 1157.034 
 
 23 81 
 
 3. 
 
 141.622 
 
 141.877 
 
 1015.254 
 
 1157.131 
 
 23 26 
 
 3 270 
 
 145 
 
 145.275 
 
 1012.890 
 
 1153.165 
 
 23 
 
 3.399 
 
 146.528 
 
 146.808 
 
 1011.823 
 
 1158.631 
 
 22 37 
 
 3.707 
 
 150 
 
 150.305 
 
 1009.385 
 
 11:9.690 
 
 22 
 
 3.9 
 
 152.0") 
 
 152.37 
 
 1007.945 
 
 1160.315 
 
 21 73 
 
 4 
 
 153.070 
 
 153.396 
 
 1007.229 
 
 1160.625 
 
 21 39 
 
 4.' 191 
 
 155 
 
 155.339 
 
 1005.876 
 
 1161.215 
 
 21 
 
 4 373 
 
 156.74 
 
 157.09 
 
 1004.452 
 
 1161.542 
 
 20.29 
 
 4.729 
 
 1G0 
 
 160.374 
 
 1002.366 
 
 1162.740 
 
 20 
 
 4.S63 
 
 ]61. 63 
 
 161.543 
 
 1001.552 
 
 1163.095 
 
 19 74 
 
 5. 
 
 1G2.33 
 
 162.722 
 
 1000.727 
 
 1103.449 
 
 19 08 
 
 5.324 
 
 163 
 
 105.413 
 
 998.852 
 
 1161.265 
 
 19 
 
 5.30 
 
 105.317 
 
 105.730 
 
 998.632 
 
 1164.362 
 
 n 
 
 5.855 
 
 109 
 
 169.45 
 
 990.035 
 
 1165.485 
 
 17.74 
 
 5.981 
 
 170 
 
 170.453 
 
 9)5.337 
 
 1165.790 
 
 17.71 
 
 c. 
 
 170.123 
 
 170.577 
 
 995.249 
 
 1165.826 
 
 17 
 
 6.346 
 
 172.6 
 
 173.07 
 
 993.513 
 
 1166.583 
 
 lrf.27 
 
 6.704 
 
 175 
 
 175 497 
 
 991.818 
 
 1167.315 
 
 1G 
 
 6.837 
 
 175.9 
 
 176.4 
 
 991 . 180 
 
 1167.580 
 
 15 67 
 
 7. 
 
 176.910 
 
 177.425 
 
 990.471 
 
 1167.896 
 
 15 
 
 7.329 
 
 178.98 
 
 179.51 
 
 989.019 
 
 1163.529 
 
 14 65 
 
 7.500 
 
 180 
 
 180.542 
 
 988.298 
 
 1168.840 
 
 14 
 
 7.82 
 
 181.877 
 
 182.427 
 
 086.980 
 
 1169.407 
 
 13 63 
 
 8. 
 
 182.910 
 
 183.481 
 
 986.245 
 
 1169.726 
 
 13 
 
 8.311 
 
 184.668 
 
 185.25 
 
 985.014 
 
 1170.204 
 
 12 87 
 
 8 :-75 
 
 185 
 
 185.591 
 
 984.774 
 
 1170.365 
 
 ia 
 
 8 802 
 
 187.272 
 
 187.885 
 
 933.360 
 
 1171.245 
 
 11. GO 
 
 9. 
 
 183.316 
 
 1S8.941 
 
 932.434 
 
 1171.375 
 
 11 
 
 9.293 
 
 189.82 
 
 190.46 
 
 981.375 
 
 1171.835 
 
 10 92 
 
 9.33 
 
 190 
 
 190.613 
 
 981. 047 
 
 1171.890 
 
 10 
 
 9.784 
 
 192.21 
 
 192.89 
 
 979.674 
 
 1172.561 
 
 9.56 
 
 10. 
 
 193. *40 
 
 193.919 
 
 978.958 
 
 1172.877 
 
 
 
 10.275 
 
 194.53 
 
 195.22 
 
 978.052 
 
 1173.272 
 
 8.79 
 
 10.33 
 
 195 
 
 195. 6&7 
 
 977.713 
 
 1173.415 
 
 8 
 
 10.767 
 
 196.742 
 
 197.46 
 
 976.480 
 
 1173.946 
 
 7.53 
 
 1.. 
 
 197.768 
 
 198.496 
 
 075 762 
 
 1174.258 
 
 7 
 
 11.253 
 
 198 9 
 
 199. C4 
 
 974.964 
 
 1174. 6"4 
 
 6.46 
 
 11.52 
 
 200 
 
 200.753 
 
 974.167 
 
 1 174 940 
 
54 
 
 Heat in a Pound of Steam. 
 
 6 
 
 r n.7 
 
 6.49 
 
 12. 
 
 5 
 
 12.24 
 
 4 
 
 12.73 
 
 3.93 
 
 12.766 
 
 3.45 
 
 13. 
 
 3 
 
 13.222 
 
 2 
 
 13.714 
 
 1.42 
 
 14. 
 
 1.17 
 
 14.122 
 
 1 
 
 14.205 
 
 
 14.G96 
 
 Gage 
 
 
 Pressure 
 
 
 lbs. per 
 
 
 gq. inch. 
 
 
 .304 
 
 15 
 
 1.304 
 
 1<S 
 
 2.304 
 
 17 
 
 3.304 
 
 18 
 
 4.304 
 
 19 
 
 6.304 
 
 20 
 
 6.304 
 
 21 
 
 7.304 
 
 22 
 
 8.801 
 
 23 
 
 9.304 
 
 24 
 
 10.304 
 
 25 
 
 11.304 
 
 26 
 
 12.304 
 
 27 
 
 13.304 
 
 28 
 
 14.304 
 
 29 
 
 15.3J4 
 
 30 
 
 200.747 
 
 201.514 
 
 973.654 
 
 1175.168 
 
 201.960 
 
 202.737 
 
 972.800 
 
 1175.537 
 
 202.924 
 
 203.712 
 
 972.120 
 
 1175.832 
 
 '204.772 
 
 205.58 
 
 970.815 
 
 1176.395 
 
 £05 
 
 205.813 
 
 970.652 
 
 1176.465 
 
 205.88-) 
 
 206.109 
 
 970.025 
 
 1176.734 
 
 206.722 
 
 207.557 
 
 969.453 
 
 1176.99 
 
 208.522 
 
 209.377 
 
 968.162 
 
 1177.539 
 
 209.560 
 
 210.428 
 
 967.427 
 
 1177.855 
 
 210 
 
 210.874 
 
 967. 11G 
 
 1177.990 
 
 210.3 
 
 211.17 
 
 966.9115 
 
 1178.0815 
 
 212 
 
 212.900 
 
 965. 7C0 
 
 1178.600 
 
 213.025 
 
 213.939 
 
 9G4 973 
 
 1178.912 
 
 216.296 
 
 217.252 
 
 962.657 
 
 1179 909 
 
 219.410 
 
 2C0.409 
 
 D60.450 
 
 1180.859 
 
 222.378 
 
 223.419 
 
 958.345 
 
 1181.764 
 
 225.203 
 
 226.285 
 
 956.343 
 
 1 182 . 628 
 
 227.917 
 
 229.0 9 
 
 954.4 5 
 
 1183.454 
 
 230.515 
 
 231.676 
 
 952.570 
 
 1184.246 
 
 233.017 
 
 234.218 
 
 950.791 
 
 1185.009 
 
 235.432 
 
 236.672 
 
 949.072 
 
 1185.744 
 
 237.752 
 
 239.029 
 
 947.424 
 
 1186.453 
 
 240.000 
 
 241.314 
 
 945.825 
 
 1187.139 
 
 242.175 
 
 243.526 
 
 944.277 
 
 1187.803 
 
 244.281 
 
 245.671 
 
 942.775 
 
 1188.446 
 
 246 326 
 
 247.748 
 
 941.321 
 
 1189.069 
 
 248.310 
 
 249.769 
 
 9^9.905 
 
 1189.674 
 
 250.245 
 
 251.738 
 
 838.925 
 
 1190.263 
 
 reduce a pound of steam at an absolute pressure of 20 pounds to 
 water at 1 io° we shall have to take out of it 
 
 1,183.554—110.110= 1,073.344 
 heat units, because the pound of steam contains 1,183.454 units, 
 of which 1 10 1 10 will remain in the water, always reckoning from 
 zero Fahrenheit. 
 
 It will be seen by comparing columns 3 and 4 that the heat in 
 the water is very nearly the same as the temperature of the water, 
 the increase on account of the greater specific heat at higher 
 temperatures being less than one heat unit between 32 ° and 212 . 
 It will be sufficiently accurate for our purpose to consider the 
 heat in the water the same as the temperature, i. e. } to consider 
 column 4 equal to column 3, letting a heat unit represent the 
 amount of heat necessary to raise a pound of water one degree 
 irrespective of the temperature. 
 
 If we represent by t the temperature at which the injection or 
 circulating water comes to the condenser and by T the tempera- 
 ture at which it leaves, the number of heat units absorbed by 
 each pound will be approximately 
 
 T—t. 
 
 The number of heat units to be taken out of a pound of steam 
 to condense it is, as we have seen above, 
 
 H—h, 
 
Water Required to Condense a Pou?id of Steam. 55 
 
 i. e. , the total heat in the steam less the heat in the resulting 
 water. 
 
 By dividing the number of heat units to be abstracted by the 
 number absorbed by each pound of condensing water we find 
 the quantity, Q, of water required to condense a pound of steam 
 
 Where H = the total heat in a pound of steam of the given 
 pressure, 
 h = the heat in a pound of water at the temperature of 
 
 the condensed steam, 
 t= the temperature at which the condensing water 
 enters the cor denser, 
 T= the temperature at which the condensing water 
 leaves the condenser. 
 
 TO FIND THE AMOUNT OF WATER REQUIRED TO CONDENSE ONE 
 POUND OF STEAM. 
 
 Rule: — From the total heat in one pound of steam of the given 
 pressure subtract the heat i?i one pound of water at the condenser 
 temperature. Divide the remainder by the rise in temperature of 
 the injection or circulating water in passing through the condenser. 
 The quotient will be the number of pounds of water required to con- 
 dense one pound of steam. 
 
 In considering the condensation of steam in an engine the value 
 of H must be taken at the terminal pressure., not at the counter- 
 pressure or vacuum line. The engine delivers the steam to the 
 condenser at the pressure existing at the point of release, and if 
 the steam were dry saturated each pound would carry to the 
 condenser the number of heat units given in column 6 of Table I. 
 There is, however, little difference in this value for the entire 
 range of terminal pressures met with in good practice, and the 
 quality of the steam may vary widely. There is little use strain- 
 ing after extreme accuracy in this particular, and we shall be 
 entirely safe for the average case and not far from right in any 
 case if we assign to H the maximum probable value of 1,190, 
 corresponding closely to a terminal pressure of 30 pounds absolute. 
 
 Call the temperature of the air pump discharge r, which, allow- 
 ing one heat unit per degree of temperature, would equal h. 
 
 Substituting these values for H and h in formula 1 we have 
 
56 
 
 To Find Quantity of Water Required 
 
 1 1 90 — T 
 T—t 
 
 (2) 
 
 APPROXIMATE RULE FOR THE QUANTITY OF CONDENSING WATER 
 REQUIRED PER POUND OF STEAM CONDENSED. 
 
 Rule: — Subtract the temperature of the air pump discharge from 
 1, 1 go and divide the remainder by the rise in temperature of the 
 condensi?ig water. 
 
 Table II has been computed by this formula and gives the 
 values of Q, i. e. , the pounds of water required to condense a 
 pound of steam for condenser temperatures of from 90 to 130 and 
 with from 5 to 90 degrees of difference in the condensing water. 
 
 In a jet condenser where the condensing water is mingled with 
 
 TABLE II.— POUNDS OF WATER REQUIRED TO CONDENSE ONE POUND OF STEAM. 
 
 1190— r 
 Q = 
 
 
 
 
 
 
 
 
 T 
 
 -t 
 
 
 
 
 
 
 
 
 T-t 
 
 
 
 
 Temperature of air pump discharge. 
 
 r 
 
 
 
 
 
 90 
 
 95 
 
 100 
 
 102 
 
 104 
 
 106 
 
 108 
 
 110 
 
 112 
 
 114 
 
 116 
 
 118 j 
 
 120 | 
 
 125 
 
 130 
 
 5 
 
 220 
 
 219 
 
 218 
 
 217.6 
 
 217.2 
 
 216.8 
 
 216 4 
 
 216 
 
 215.6 
 
 215.2 
 
 214.8 
 
 214.4 
 
 214 
 
 213 
 
 212 
 
 10 
 
 110 
 
 109.5 
 
 109 
 
 108.8 
 
 108.6 
 
 108.4 
 
 108.2 
 
 108 
 
 107.8 
 
 107. 6 
 
 107.4 
 
 107.2 
 
 107 
 
 106.5 
 
 106 
 
 15 
 
 73.3 
 
 73 
 
 72.7 
 
 72.5 
 
 72.4 
 
 72.3 
 
 72.1 
 
 72 
 
 71.9 
 
 71.7 
 
 71.6 
 
 71.5 
 
 71. 3 1 
 
 71 
 
 70.7 
 
 20 
 
 55 
 
 54.7 
 
 54.5 
 
 54.4 
 
 54.3 
 
 54.2 
 
 54.1 
 
 54 
 
 5J.9 
 
 53.8 
 
 53.7 
 
 53.6 
 
 53.5 
 
 53.2 
 
 53 
 
 25 
 
 44 
 
 43.8 
 
 43. . 
 
 43.5 
 
 43.4 
 
 43.4 
 
 43.3 
 
 43.2 
 
 43.1 
 
 43 
 
 42.9 
 
 42.9 
 
 42.8) 
 
 42.6 
 
 42.4 
 
 30 
 
 36.7 
 
 36.5 
 
 36.3 
 
 36.3 
 
 , c 6.2 
 
 36.2 
 
 36.1 
 
 36 
 
 35.9 
 
 35.9 
 
 35.8 
 
 35.7 
 
 35.7 
 
 35.5 
 
 35.3 
 
 3) 
 
 31.4 
 
 31.3 
 
 31.1 
 
 31.1 
 
 31.0 
 
 31 
 
 30.9 
 
 30.8 
 
 30.8 
 
 30.7 
 
 • 0.7 
 
 30.6 
 
 30.5 
 
 30.4 
 
 30? 
 
 40 
 
 27.5 
 
 27.4 
 
 27.2 
 
 27.2 
 
 27.1 
 
 27.1 
 
 '27 
 
 27 
 
 26.9 
 
 26.9 
 
 26.8 
 
 '26.8 
 
 26.7 
 
 26.6 
 
 26.5 
 
 45 
 
 24.4 
 
 24.3 
 
 24.2 
 
 24.2 
 
 24.1 
 
 24.1 
 
 24 
 
 24 
 
 23.9 
 
 23.9 
 
 23.9 
 
 23.8 
 
 23.8 
 
 23.7 
 
 23 5 
 
 50 
 
 22 
 
 21.9 
 
 21.8 
 
 21.8 
 
 21.7 
 
 21.7 
 
 21.6 
 
 21.6 
 
 21.6 
 
 21.5 
 
 21.5 
 
 21.4 
 
 21.4 
 
 21.3 
 
 21.2 
 
 55 
 
 20 
 
 19.9 
 
 19.8 
 
 19.8 
 
 19.7 
 
 19.7 
 
 19.7 
 
 19.6 
 
 19.6 
 
 19.6 
 
 19.5 
 
 19. 5j 
 
 19.4 
 
 19.4 
 
 19. S 
 
 60 
 
 18.3 
 
 18.2 
 
 18.2 
 
 18.1 
 
 18.1 
 
 18.1 
 
 18 
 
 18 
 
 18 
 
 17.9 
 
 17.9 
 
 17 9 
 
 17.8 
 
 17.7 
 
 17 7 
 
 G5 
 
 16.9 
 
 16.8 
 
 16.8 
 
 16.7 
 
 16.7 
 
 16.7 
 
 16.6 
 
 16.6 
 
 16.6 
 
 16.5 
 
 16.5 
 
 16.5 
 
 16.5 
 
 16.4 
 
 16.3 
 
 70 
 
 15.7 
 
 15.6 
 
 15.6 
 
 15.5 
 
 15.5 
 
 15.5 
 
 15.4 
 
 15.4 
 
 15.4 
 
 15.4 
 
 15.3 
 
 15.3 
 
 15.3! 
 
 15.2 
 
 15.1 
 
 75 
 
 14.7 
 
 14.6 
 
 14.5 
 
 14.5 
 
 14.5 
 
 14.4 
 
 14.4 
 
 14.4 
 
 11.4 
 
 14 3 
 
 14.3 
 
 14.3 
 
 14.3! 
 
 14.2 
 
 14.1 
 
 80 
 
 13.7 
 
 13.6 
 
 13,6 
 
 13,6 
 
 13,6 
 
 13.5 
 
 13.5 
 
 13.5 
 
 13.5 
 
 13.4 
 
 13.4 
 
 13 4 
 
 13.41 
 
 13.3 
 
 13.2 
 
 85 
 
 12,9 
 
 12.8 
 
 12.8 
 
 12,8 
 
 12,8 
 
 12.7 
 
 12.7 
 
 12.7 
 
 12 7 
 
 12.6 
 
 12.6 
 
 12.6 
 
 12.6 
 
 12.5 
 
 12.5 
 
 90 
 
 12 2 
 
 12.2 
 
 12.1 
 
 12.1 
 
 12.1 
 
 19 
 
 12 
 
 12 
 
 12 
 
 11.9 
 
 11.9 
 
 11.9 
 
 11.9 
 
 11.8 
 
 11.8 
 
 the steam T and r become identical and formula becomes 
 
 a — IT 9 °— T 
 
 V T—t 
 
 Table III has been computed by this formula and gives the 
 value of Q, i. e., the number of pounds of injection water required 
 per pound of steam with the injection water from 35 to 100 
 degrees and the air pump discharge from 90 to 140 . 
 
 SIZE OF AIR PUMP FOR JET CONDENSER. 
 
 If we designate by H^the weight of steam to be condensed per 
 hour, the number of pounds of water to be handled per hour by 
 the pump will be 
 
 W(Q+i). 
 
Displacement Required for Water. 
 
 0/ 
 
 For example, if we had a ioo horse power engine using 20 
 pounds of steam per hour per horse power the weight JVoi steam 
 to be condensed per hour would be 20 X 100= 2,000 pounds. If 
 it takes 20 pounds of water to condense a pound of steam, then 
 for each pound of steam condensed we shall have 
 
 20 -f- 1 pounds 
 of water to pump, 20 pounds of injection and one pound of con- 
 densed steam. For 2,000 pounds we shall have 
 W (g-f 1) = 2,000(20+ 1). 
 
 XARLE III. 
 
 a, 
 ® * 2 
 
 £ 3(1| 
 
 E-t ° w 
 
 92 
 91 
 96 
 98 
 100 
 102 
 104 
 106 
 108 
 110 
 112 
 114 
 116 
 118 
 120 
 122 
 124 
 126 
 128 
 130 
 132 
 134 
 136 
 138 
 140 
 
 -POUNDS OF INJECTION WATER .REQUIRED PER POUND OF 
 STEAM CONDENSED. 
 
 Entering Temperature of Injection Water t. 
 
 3j 40 45 50 55 GO 65 70 75 
 
 90 95 100 
 
 I I 
 
 Pound.3 of Condensing Water Required per Pound of Steam. Q = 
 
 1190— T 
 T—t 
 
 20 
 19.2 
 18 6 
 17.9 
 17 3 
 16.8 
 16.2 
 15.7 
 15.3 
 14.8 
 14.4 
 14.0 
 13.6 
 13.3 
 12.9 
 12.6 
 12.3 
 12.0 
 11.7 
 11.4 
 11.2 
 10.9 
 10.7 
 10.4 
 10.2 
 10.0 
 
 »0 
 
 24.4 
 
 21.1 
 
 23.4 
 
 20 3 
 
 22.4 
 
 19.5 
 
 21.4 
 
 18.8 
 
 20.6 
 
 18.2 
 
 19.8 
 
 17.5 
 
 19.1 
 
 17.0 
 
 18.4 
 
 16.4 
 
 17.8 
 
 15.9 
 
 17.2 
 
 15.4 
 
 16.6 
 
 15.0 
 
 16.1 
 
 14 5 
 
 15.6 
 
 14.1 
 
 15.1 
 
 13.7 
 
 14.7 
 
 13.4 
 
 14.3 
 
 13.0 
 
 13.9 
 
 12.7 
 
 13.5 
 
 12.4 
 
 13.1 
 
 12.1 
 
 12.8 
 
 11.8 
 
 12.5 
 
 11.5 
 
 12.2 
 
 11.2 
 
 11.9 
 
 11.0 
 
 11.6 
 
 10.7 
 
 11.3 
 
 10.5 
 
 11.1 
 
 27.5 
 26.1 
 24 9 
 23.6 
 22.7 
 21.8 
 20.9 
 20.1 
 19.4 
 18.7 
 18.0 
 17.4 
 16.8 
 16.3 
 15.8 
 15.3 
 14.8 
 14.4 
 14.0 
 13.6 
 13.2 
 12.9 
 12.6 
 12.3 
 12.0 
 11.7 
 
 31.4 
 
 36.7 
 
 29.7 
 
 34.3 
 
 28.1 
 
 32.2 
 
 26.7 
 
 30.4 
 
 25 4 
 
 28 7 
 
 24.2 
 
 27.2 
 
 23.1 
 
 25.9 
 
 21.2 
 
 24.7 
 
 21.3 
 
 23.6 
 
 20.4 
 
 22.5 
 
 19.6 
 
 21.6 
 
 18.9 
 
 20.7 
 
 18.2 
 
 19 9 
 
 17.6 
 
 19.2 
 
 17.0 
 
 18.5 
 
 16.5 
 
 17.8 
 
 15.9 
 
 IT. 2 
 
 15.4 
 
 16.7 
 
 15.0 
 
 16.1 
 
 14.5 
 
 15.6 
 
 14.1 
 
 15.1 
 
 13.7 
 
 14.7 
 
 13 4 
 
 14.3 
 
 13.0 
 
 13.9 
 
 12.7 
 
 13.5 
 
 12 4 
 
 13.1 
 
 44.0 
 
 40.7 
 37.8 
 35.3 
 30.1 
 31.1 
 29.4 
 27.8 
 26.4 
 25.2 
 24.0 
 22.9 
 42.0 
 21.1 
 20.2 
 19.5 
 18.7 
 18.1 
 17.4 
 16 9 
 16.3 
 15.7 
 15.3 
 14.8 
 14.4 
 14.0 
 
 55.0 
 49.9 
 45.7 
 42.1 
 39.0 
 36.3 
 34.0 
 31.9 
 30.1 
 28.5 
 27.0 
 25.7 
 24.5 
 23.3 
 22.3 
 21.4 
 20.5 
 19.7 
 19.0 
 18 3 
 17.7 
 17.1 
 16.5 
 16.0 
 15.5 
 15.0 
 
 73 3 
 64.6 
 57.7 
 52.1 
 47.5 
 43.6 
 40.3 
 37.4 
 35.0 
 32.8 
 30.9 
 29.1 
 27.6 
 26.2 
 24.9 
 23.8 
 22.7 
 21.8 
 20.9 
 20.0 
 19.3 
 18.6 
 17.9 
 17.3 
 16.7 
 16.2 
 
 110.0 
 91.5 
 78 1 
 68.4 
 60.7 
 54.5 
 49.5 
 45.2 
 41.7 
 38.6 
 36.0 
 33.6 
 31.6 
 29.8 
 28.2 
 26.7 
 25.4 
 24.2 
 23.1 
 22.1 
 21.2 
 20.3 
 19.6 
 IS. 8 
 18.1 
 17.5 
 
 220.0 
 156.8 
 121.8 
 99.4 
 84.0 
 72.7 
 64.0 
 57.2 
 51.6 
 47.0 
 43.2 
 39.9 
 37.1 
 34.6 
 32.5 
 30.6 
 28.9 
 27.3 
 26.0 
 24.7 
 23.6 
 22 5 
 21.6 
 20.7 
 19.8 
 19.1 
 
 549.0 
 274 .-0 
 182.3 
 136.5 
 109.0 
 90.7 
 77.6 
 G7.7 
 G0.1 
 51.0 
 49.0 
 44.8 
 41.3 
 38 3 
 35.7 
 33.4 
 31.4 
 29.6 
 27.9 
 26.5 
 25.2 
 24.0 
 22.9 
 21.9 
 21.0 
 
 364.0 
 218.0 
 155.4 
 120.7 
 98.5 
 83.2 
 72.0 
 63 4 
 56.6 
 51.1 
 46.6 
 42.8 
 39.6 
 36.8 
 34.3 
 32.2 
 30.3 
 28.6 
 27.1 
 25.7 
 24.5 
 23.3 
 
 544.0 
 271.5 
 
 180.7 
 135.2 
 1084) 
 89.8 
 76.9 
 67.1 
 59.6 
 53.5 
 48.5 
 44.4 
 40.9 
 37.9 
 35.3 
 33.1 
 31.0 
 29.2 
 27.7 
 26.2 
 
 It takes in round numbers 28 cubic inches to make a pound of 
 water at ordinary condenser temperatures, so that if we multiply 
 this by 28 we shall get the number of cubic inches of water to be 
 pumped per hour. By dividing this by 60 we get the number of 
 cubic inches to be pumped per minute, and our formula so far 
 becomes 
 Water pumped per minute= 
 
 28 
 W (04- 1) ^-cubic incheSc 
 v 60 
 
58 Additional Displacement for Air. 
 
 But in addition to the water we have a considerable quantity of 
 air to handle, and we cannot count upon an efficiency of ioo per 
 cent, so we must provide a pump of a displacement considerably 
 more than the volume of the water. I,et us call the ratio of the 
 pump displacement to the volume of the water R. For instance, 
 if the displacement were twice the volume of the water or the 
 pump were allowed to half fill with water, R would be 2. Then 
 the pump displacement D in cubic inches per minute would be 
 
 If there is any standard value for R, if we can determine what 
 proportion of their displacement it is safe or advisable to allow 
 pumps of the different types to fill, we can combine this standard 
 
 28 
 
 value of R with the fraction ~^~ into a coefficient K and the 
 formula becomes 
 
 D = KW{Q+i). (3) 
 
 For instance suppose it was the usual practice to use a pump 
 having a displacement of twice the volume of the water to be 
 pumped, i. e., to let the pump fill half full of water, then R 
 Vould equal 2, and 
 
 60 60 ^ 
 
 andZ)=. 9 3 W(Q+i). 
 
 Table IV gives the values of K for various values of R. If 
 the pump fills with water to 60 per cent, of its displacement 
 (column 1), i. e. y if the displacement is 1.667 times the volume 
 of the water (column 2), the value of A'wouldbe .78 (column 3). 
 
 In order to establish the values of K used in current practice 
 with various kinds of pumps we have obtained from such manu- 
 facturers as were willing to furnish them the data contained in 
 Tables V to XIII. From the data in columns 2 to 6 the displace- 
 ment D in cubic inches per minute has been computed, corrected 
 for the rod, when its diameter (column 3) was known. Columns 
 9 and 10 give the value of W y i. e. } the weight of steam con- 
 densed per hour which the pump is adapted to take care of by the 
 builder's rating. The values in column 10 are all reduced to 20 
 pounds of injection water to 1 of steam. When the builder's 
 rating is based upon a different value of Q it is to be found in 
 column 8. In columns 13 and 14 are the values of A" correspond- 
 
To Find Size of Air Pump, 
 
 59 
 
 ing with the ratings for jet and surface condensers respectively. 
 
 Take, for example, the Conover vertical single acting air pump, 
 Table V. For a jet condenser the value of K for everything but 
 the smallest size is .75 (column 13). In column n is given the 
 capacity computed by the formula as given at the head of the 
 column, which is simply a transposition of formula 3, taking K 
 = . 75 and the values 
 there given will be seen 
 to run very close to the 
 builder's rating. 
 
 Knowing the value of 
 K the process becomes 
 very simple. Suppose 
 we have a 500 horse 
 power engine using 20 
 pounds of steam per hour 
 per horse power; that 
 the temperature of the 
 injection water will be 
 for considerable periods 
 as high as 65 °, and we 
 want to keep the hot well 
 or condenser temperature 
 down to no°. What 
 size Conover pump 
 should we require ? We 
 see from Table III that 
 it will take 24 pounds of 
 injection water per pound 
 of steam; then 
 
 Q= 24; 
 
 jv= 500 x 20 = 10,- 
 000; 
 
 TABLE IV. -VALUES OF K FOR 
 
 DIFFERENT 
 
 RATIOS OF DISPLACEMENT TO VOLUME 
 
 OF 
 
 WATER HANDLED 
 
 
 1 
 
 2 
 
 3 
 
 Per cent of Air 
 
 Ratio of Air 
 
 
 Pump Dis- 
 
 Pump Displace- 
 
 Value 
 
 placement Filled 
 
 ment to Volume 
 
 of 
 
 with Water. 
 
 of Water. 
 
 K. 
 
 V 
 
 D 
 
 28 
 
 100 — 
 
 R = — 
 
 K = -R 
 
 D 
 
 V 
 
 60 
 Surface. 
 
 5 
 
 20 
 
 9.33 
 
 5.26 
 
 19 
 
 8.87 
 
 5.56 
 
 18 
 
 8.40 
 
 5.88 
 
 17 
 
 8.00 
 
 6.26 
 
 16 
 
 7.47 
 
 6.66 
 
 15 
 
 7 
 
 7.14 
 
 14 
 
 6.P3 
 
 7.69 
 
 13 
 
 6.07 
 
 8.33 
 
 12 
 
 5.60 
 
 9.09 
 
 11 
 
 6.13 
 
 10.00 
 
 10 
 
 4.67 
 Jet. 
 
 33.33 
 
 3 
 
 1.4 
 
 35 
 
 2.941 
 
 1.33 
 
 36 
 
 2.778 
 
 1.30 
 
 38 
 
 2.632 
 
 1.23 
 
 40 
 
 2.5 
 
 1.17 
 
 42 
 
 2.381 
 
 1.11 
 
 44 
 
 2.273 . 
 
 1.07 
 
 46 
 
 2.174 
 
 1.02 
 
 47 
 
 2.143 
 
 1 
 
 48 
 
 2.083 
 
 .97 
 
 50 
 
 2 
 
 .93 
 
 52 
 
 1.923 
 
 .90 
 
 54 
 
 1.852 
 
 .86 
 
 56 
 
 1.786 
 
 .83 
 
 58 
 
 1.724 
 
 .80 
 
 60 
 
 1.667 
 
 .78 
 
 62 
 
 1.613 
 
 .75 
 
 64 
 
 1.5*2 
 
 .73 
 
 66 
 
 1.515 
 
 .71 
 
 66.67 
 
 1.5 
 
 .70 
 
 68 
 
 1.471 
 
 .69 
 
 70 
 
 1.429 
 
 .67 
 
 72 
 
 1.389 
 
 .65 
 
 74 
 
 1.351 
 
 .63 
 
 75 
 
 1.333 
 
 .62 
 
 76 
 
 1.316 
 
 .61 
 
 78 
 
 1.282 
 
 .GO 
 
 80 
 
 1 250 
 
 .58 
 
 75; 
 
 K 
 
 and 
 
 D= K W (Q -f- 1) = .75 X 10,000 X 25 = 187,500 cu. in. 
 per min. 
 
 The sizes nearest to this capacity are the numbers 1 1 and 1 2 
 
60 To Find Size of Air Pump. 
 
 (which, by the way, have the same size of air cylinder but differ- 
 ent steam cylinders), having a capacity of 158,340, and the 
 numbers 13 and 14, with a capacity of 204,781 cubic inches per 
 minute. The purchaser can determine if it is safe in his case to 
 take the next smaller or whether the next larger is necessary. 
 
 For the double-acting horizontal pumps the value of K runs 
 very close to unity in several of the tables, although some of the 
 makers rate them so high as to bring K down to a figure which 
 gives them a considerably greater efficiency than the vertical 
 single-acting pumps. What incongruities there are in the columns 
 of K are evidently due to erratic ratings, for there should be no 
 reason why one pump of the same kind and make should have a 
 greater displacement per pound of water handled than the size 
 next to it, saving always that very small sizes may be less efficient 
 than the larger. Where the diameter of the rod is not given 
 there would be a greater proportional difference between the net 
 and gross displacement in the smaller sizes, which would call for 
 a larger value of K for a very small pump where the displace- 
 ment is uncorrected for the rod. As for the difference in the 
 values of K as given by the ratings of the different makers we 
 must leave our readers to judge whether there should be so much 
 difference in the efficiency of the respective pumps that one could 
 be allowed to fill over 78 per cent. , while the other fills less than 
 50 per cent, of the stroke. 
 
 From the data presented the conclusion would appear warranted 
 that a safe value for K would be .75 for vertical single-acting 
 pumps and unity for horizontal double-acting pumps, and that 
 pumps selected by the following formulas would be very close to 
 what the makers would recommend for the capacity required: 
 
 For horizontal double- acting pumps: — 
 
 D= W(Q+t) (4) 
 
 For vertical singlk-acting pumps: — 
 
 Z>=. 7 5 1V(Q+i) (5) 
 
 to determine the size of air pump required for a jet 
 
 condenser. 
 
 RULE: — Multiply the number of pounds of steam to be condensed 
 per hour by one plus the number of pounds of injection water ?r- 
 quired per pound of steam. The product will be the required pump 
 
How Pumps Should be Rated. 6r 
 
 displacement in cubic indies per minute for a horizontal double- 
 acting pump. For a single-acting vertical pump multiply the 
 above product by .75. 
 
 In column 1 1 of the tables are given the capacities calculated 
 by formula 4 or 5, according to the type of pump. In all except- 
 ing a few instances of abnormally high rating the capacities will 
 be seen to agree substantially with the rated capacities of the 
 builders in column 9. 
 
 We are informed by one of the makers that they find the long 
 rating perfectly safe, because they always use the size next above 
 the required' computed capacity. For instance, Dean Bros, rate 
 their 7X I2 X I2 at 5,535 pounds of steam per hour, with 26 
 pounds of injection to one of steam, which gives a value for K of 
 .632. This requires the pump to fill with water to almost 74 per 
 cent, of its volume (Table IV), a condition which could not be 
 counted upon to preserve a good vacuum with a double-acting 
 horizontal pump, but this pump is used for everything between 
 2,300 and 5,500. With a capacity of about 2,950 its coefficient 
 becomes unity and its capacity ample. Much of the time, too, 
 the temperature of the injection would be such that less than 26 
 pounds of injection would be used, and it is improbable that the 
 maximum conditions of load and injection temperature will come 
 together. On a pinch, too, the speed of the pump could be 
 increased above that given in columns 5 and 6. We think, how- 
 ever, that the pump should be rated at what it will do continu- 
 ously and comfortably under the given conditions, and the 
 engineer be allowed to decide how much he wishes to exceed that 
 capacity in the maximum demand which he is likely to put upon 
 it. The reduction of the ratings to a common unit of K= 1 for 
 horizontal double-acting pumps and K= .75 for single-acting 
 vertical pumps (column 11) makes this possible and easy. It 
 should be noticed that this column is computed for 20 pounds of 
 injection to one of steam. 
 
 In selecting a pump, it should be remembered that the work 
 done depends upon the volume of air and water delivered against 
 the atmospheric pressure, and not upon the size of the pump. In 
 Fig. 4, which is a section of the Conover single-acting pump, 
 suppose the volume of air and water in the chamber B to be so 
 small that the air would not be compressed enough to lift the head 
 
62 
 
 Work Performed by Air Pump. 
 
 valves. On the upward stroke the pump performs the work of 
 lifting the water resting on the piston and of compressing the air. 
 On the downward stroke the water, in descending, gives back 
 the work required to lift it, and the air in expanding the work 
 required to compress it, so that no work is done except that 
 required to overcome friction. When the volume of air and water 
 in B becomes so great that the head valves are lifted the remainder 
 of the stroke is completed against the pressure of the atmosphere, 
 and the work done is proportional to the volume of air and water 
 
 Fig. 4. 
 
 delivered at atmospheric pressure. Aside, then, from the 
 additional investment in and friction of the larger pump, it is at 
 no disadvantage over the smaller. 
 
 In computing the displacement of a single-acting pump, it 
 should be noted that when a foot- valve is used, the pump is to 
 an extent double acting. This will be seen by reference to Figs. 
 
Single Acting Pump with Foot Valve is Double Acti?ig. 63 
 
 2 and 3. When the piston is in its highest position, as in Fig. 2, 
 we have the volume between the head and the foot valves con- 
 taining only the piston. When the piston is in its lowest position 
 (Fig. 3) this volume has been further reduced by the volume of 
 the trunk, and a volume equal to the cross sectional area of the 
 trunk, multiplied by the 
 
 length of the stroke, must I Fig 2 Fig. 3. 
 
 have been discharged i||||| 
 
 through the head valves on 
 the downward stroke. 
 When the area of the trunk 
 becomes equal to that of 
 the annular space around it, 
 the pump discharges as 
 much on the downward as 
 upon the upward stroke. Where no foot-valve is used, as in 
 Fig. 1, the water is held against the piston by the head at A y 
 avoiding the disagreeable chug which occurs when the piston is 
 allowed to come against a confined body of water. 
 
 The factor of uncertainty in air pump work is the air entering 
 
 by leakage. This air 
 entering at the atmospheric 
 pressure of. say, 15 pounds, 
 I expands in a vacuum of 26 
 I inches to over 7 times its 
 £ original volume, and this 
 I increased volume must be 
 I provided for in the displace- 
 3 ment of the air cylinder. 
 This factor is therefore an 
 exceedingly important one, 
 4 and is very variable. Some 
 plants are tight, others are 
 
 no eixT«F 
 
 BY ICflK/VGE 
 
 JNDENSING WATER 
 
 -2O-V0LuMtS- 
 
 £4 VOLUMES 
 
 5<> W.JLUME 
 
 Fig. 
 
 not. Generally plants using a small amount of steam per horse 
 power have a large leakage factor, because while the amount of 
 steam used per horse power is decreased, the leakage is liable to 
 go the other way, the pressure in the lower pressure cylinder be- 
 ing much of the time below that of the atmosphere. 
 
64 Size of Air Pump for Surface Condenser. 
 
 SIZE OF AIR PUMP FOR SURFACE CONDENSER. 
 
 In a jet condenser, the air pump has to handle a comparatively 
 large amount of water. In the surface condenser it handles a 
 small volume of water and a large volume of air. Assume 20 
 pounds of injeccion to one of steam condensed, air carried by the 
 water one- third the volume of the water when expanded, and an 
 air pump with a displacement about two and a half times the 
 volume of the water to be moved. Under these conditions we 
 should have in Fig. 1 : 
 
 At A the condensed steam = 1 vol. 
 
 At B the condensing water = 20 vols. 
 
 At Cthe air entering with the water = 7 vols. 
 
 And at D the space which it is found necessary to provide for 
 the air entering by leakage and to cover the deficiencies of the 
 pump, consisting of 24 volumes. 
 
 In a surface condenser we have to handle only the water 
 represented by A. The space B, therefore, can be cut out of the 
 diagram, as can also the space C, as the only water which can 
 bring in air is the comparatively small quantity used for make-up. 
 We are liable to have as much air enter by leakage into a surface 
 as into a jet system, so that the portion of the space D which is 
 required for air entering by leakage, and this is the greater por- 
 tion of it, will remain unchanged. The portion required to cover 
 the lack of perfection in the pump will diminish with the volume 
 pumped. With a pump of half the size a less number of cubic 
 inches of volume will be lost by failure to fill, slippage, failure of 
 valves to seat, etc. 
 
 If D were left as it is, we should have a displacement 25 times 
 the volume of the water pumped. The practice of the pump 
 companies generally is to give the air pump a displacement equal 
 to 20 times the volume of the condensed steam, if it is a horizontal 
 double-acting, and 1 2 times if it is vertical single-acting. The 
 Conover company give their pumps a displacement of only 10 
 times the volume of the condensed steam. 
 
 The values of A" for these ratios are: 
 R K 
 
 10 = 4.67 
 12 = 5.6 
 20 = 9-33 
 
Air Pump for Surface Condenser. 65 
 
 For general use these values may safely be taken at 9 for a 
 horizontal double-acting, and at 5 for a vertical single-acting 
 pump. Since there is no injection the volume of water to be 
 handled is simply W, and the formulas become: 
 For a horizontal double-acting pump 
 
 D = 9 W (6) 
 
 For a vertical single-acting pump 
 
 B = 5 W (7) 
 
 or generally 
 
 D = KW (8) 
 
 TO DETERMINE THE SIZE OF AIR PUMP REQUIRED FOR A SURFACE 
 
 CONDENSER. 
 
 Multiply the number of pounds of steam to be condensed per hour 
 by 9 for a horizontal double-acting or by 5 for a vertical single- 
 acting pump. The product will be the air pump displacement 
 required in cubic inches per minute. 
 
 In column 1 2 of the tables are given the capacities calculated 
 by formula 6 or 7, according to the type of pump. A comparison 
 between columns 10 and 12 will show how nearly the formula 
 with the constants chosen will come to the builder's rating. Of 
 course the general formula 8 may be employed, the user choosing 
 his own value of K. 
 
 CONDENSING SURFACE REQUIRED. 
 
 In the early days of the surface condenser it was thought 
 necessary to provide a cooling surface in the condenser equal to 
 the heating surface in the boilers, the idea being that it would 
 take as much surface to transfer the heat from a pound of steam 
 to the cooling water and condense the steam as it would to 
 transfer the heat from the hot gases to the water in the boiler and 
 convert it to steam. The difference in temperature, too, between 
 the hot gases and the water in the boiler is considerably greater 
 than that between the steam in the condenser and the cooling 
 water. Steam, however, gives up its heat to a relatively cool 
 surface much more readily than do the hot furnace gases, and the 
 positively circulated cooling water takes up that heat and keeps 
 the temperature of the surfaces down, while in a boiler the 
 absorption depends in a great measure upon the ability of the 
 water by natural circulation to get into contact with the surface 
 
66 Cooling Surface in Surface Condensers. 
 
 and take up the heat by evaporization. It has been found, there- 
 fore, that a much smaller surface will suffice in a condenser than 
 in the boilers which it serves. 
 
 The Wheeler Condenser and Engineering Company, who make 
 a specialty of surface condensers, say that one square foot of 
 cooling surface is usually allowed to each 10 pounds of steam to 
 be condensed per hour, with the condensing water at a normal 
 temperature not exceeding 75 °. This figure seems to be gener- 
 ally used for average conditions. Special cases require special 
 treatment. For service in the tropics the heating surface should 
 be at least ten per cent, greater than this estimate: Where there 
 is an abundance of circulating water the surface may be much 
 less, as with a keel condenser, where 50 pounds of steam is some- 
 times condensed per hour per square foot of surface; or a water 
 works engine, where all the water pumped is discharged through 
 the condenser and not appreciably raised in temperature, probably 
 condensing 20 to 40 pounds per hour per square foot of surface. 
 
 Mr. J. M. Whitham, in a paper upon "Surface Condensers," 
 presented to the American Society of Mechanical Engineers,* 
 gives the following formula for calculating the surface required: 
 
 C— WL 
 
 180 ( T—.t) 
 
 Where 
 S-= the surface in square feet, 
 W= the weight of steam condensed per hour, 
 L = the latent heat of steam at the condenser temperature, 
 T= the temperature of the condenser, or the air pump dis- 
 charge, 
 and / = the average temperature of the circulating water, i. e. , the 
 sum of its initial and final temperatures, divided by 2. 
 For ordinary conditions this reduces to 
 
 o 17 W 
 
 *~ 180 
 
 or one square foot of heating surface to about 10.6 pounds of steam 
 condensed per hour. 
 
 This refers to the ordinary arrangement of horizontal brass 
 tubes of small diameter to the surface condenser as ordinarily 
 
 *See Trans. A S. M. E., Vol. IX, p, 417. 
 
Size of Injectiori Main. 67 
 
 used. With other arrangements of surface, etc., it might not 
 apply. 
 
 CONDENSING WATER PER HORSE POWER IN GALLONS. 
 
 The value of Q can be reduced to gallons by dividing by 8.25, 
 for since one pound equals 28 cubic inches one pound equals 
 
 2M = ^25 0fa g all0n - 
 
 If we let S = the steam required per horse power per hour, the 
 weight of steam to be condensed per hour for a given engine will be 
 
 W=/fPXS 
 The condensing water required in pounds per hour will be 
 WQ = //PXQXS 
 in gallons per hour, 
 
 JfPXQXS 
 8.25 
 or, in gallons per minute, 
 
 HPXQXS ^ HPXQXS 
 
 60X8.25 495 
 
 s 
 
 This is gallons per minute per horse power. 
 
 Taking 20 pounds of steam per horse power per hour and 25 
 pounds of condensing water per pound of steam the condensing 
 water per horse power = 
 
 — — ass - — gals, per min., 
 
 495 495 
 
 or just about a gallon per minute per horse power, which is a 
 a much used value. 
 
 SIZE OF INJECTION MAIN. 
 
 The injection main should be so proportioned that the velocity 
 of flow does not exceed 300 feet per minute, a velocity which will 
 be closely approximated by making the diameter of the pipe the 
 square root of the quotient of the pounds of condensing water 
 required per hour divided by 6,000. 
 
 For examp 1 e. to condense 2,000 pounds of steam per hour with 
 24 pounds of injection per pound of steam would require 
 24 X 2,000 = 48,000 pounds of injection water per hour. 
 
 Divide this by 6,000 and extract the square root and you have 
 the pipe diameter, 
 
 48,000 -f- 6,000 = 8 
 
68 Relation of Temperature and Vacuum 
 
 The pipe should evidently be 3 inches, the square of 2.5, the 
 next lower size being 6.25. 
 
 If there were no air present in the condenser the temperature 
 for a given vacuum or absolute pressure would be that given in 
 Table 1. There is in the condenser, however, the pressure not 
 only of the steam arising from the water, but that of the enclosed 
 air, so that for a given condenser temperature the absolute 
 pressure will be higher, i. e. , the vacuum will be less than in- 
 dicated by the table. With a temperature of air pump discharge 
 of 120 , for instance, we should have, if there were nothing pres- 
 ent but the water and the steam arising from it, an absolute 
 pressure of 1.682 pounds per square inch, or a vacuum of 26.5 
 inches. We cannot have a lower absolute pressure, i. e. y a better 
 vacuum, with this temperature, because the water at this temper- 
 ature will continue to give off steam of this pressure and keep the 
 condenser full of it, no matter how much capacity w r e have to our 
 air pump. Now, if we admit a little air we shall have an 
 additional pressure with no increase of temperature, and of course 
 there will be some air present. For this reason it is common to 
 see condensers running with a discharge temperature of ioo°, 
 which by the table should give a vacuum of over 28 inches, with 
 the gage showing 26 or less. 
 
6 9 
 
 §2? 
 ©2 « 
 
 £p 
 
 - 5 
 
 Sal* 
 a n 
 
 8&$8S&&S(3ls5&& 
 
 4>A 
 
 0) 
 
 1 
 
 A 
 
 00 I>- t- t- l- l- l- t- t- l- l- L- l- 
 
 tl 
 
 
 2 3 
 08 9 
 
 S"i?« « 
 
 * i 
 
 r, m c :o n c l». a a ^K) ^ f i 
 
 Hi C5 O — t- 9 C5 N-fHt-H l- 
 
 B 
 
 ^ 
 
 4s 
 
 + 
 
 <y 
 
 o 
 11 
 
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78 
 
 INDEX. 
 
 B 
 
 /\bsolute Pressure, 9. 
 
 Air and Circulating Pumps driven by 
 motors, 40. 
 
 Air-Pump for Surface Condenser, 65. 
 
 Air-Pump ; location of, 27. 
 
 Air-Pump rating, 61. 
 
 Air-Pump ; To find size of, 59-60. 
 
 Air-Pump ; Total work of, 62. 
 
 Air- Pump ; Types of, 39. 
 
 Air-Pump Valves ; lifting or clattering of, 
 27. 
 
 Air-Pump ; Vertical, 22. 
 
 Air; Pumping, 10. 
 
 Area of Cooling Surface in Surface Con- 
 denser, 65-66. 
 
 Atmosphere ; Pressure of the, 3. 
 
 arr Horizontal Double-Acting Pumps ; 
 Table of, 77. 
 
 Capacity of a Condenser ; To calculate 
 the, 65-68. 
 
 Circulating Pump, 39-40. 
 
 Cooling Surface of a Surface Condenser, 
 65-66. 
 
 Cooling Towers, 26 
 
 Cooling Water required for condensing, 
 15. 16, 55-57, 67. 
 
 Condensation in a Cylinder, 18-19 
 
 Condensation ; Production of a vacuum by 
 means of, 11. 
 
 Condenser Capacity, 52-68 
 
 Condenser ; Induction See Induction Con- 
 denser. 
 
 Condenser; Injector. See Injector Con- 
 denser , 
 
 Condenser ; Jet. See Jet Condenser 
 
 Condenser; Siphon See Injector Con- 
 denser, 
 
 Condenser; Surface See Surface Con- 
 denser 
 
 Condenser unavailable, 17 
 
 Condensers ; Independent and direct- 
 driven, 21. 
 
 Condensing by Evaporation, 26. 
 
 Condensing Engine ; How to start and stop 
 a, 33. 35, 5i- 
 
 Condensing; Gain due to, 12-14. 
 
 Condensing , L,oss in temperature of feed- 
 water due to, 14. 
 
 Condensing ; Water required for, 15, 16, 
 55-57. 67 
 
 Condensing Water per Horsepower, in 
 gallons, 67. 
 
 Condensing Water ; Pump displacement 
 
 required for, 57. 
 Conover Vertical Single-Acting Pumps ; 
 
 Table of, 69. 
 Cylinder Condensation, 18-19. 
 
 ^J iagram of Maximum Efficiency, 20. 
 
 Dean Bros.' Horizontal Double-Acting 
 Pumps, Table of, 70. 
 
 Dean Bros. ' Twin Cylinder Vertical Single- 
 Acting Pumps ; Table of, 76. 
 
 Deane Horizontal Double-Acting Pumps ; 
 Table of, 75. 
 
 ^^fficiency ; Diagram of maximum, 20. 
 Engine Equipped with Independent Jet 
 
 Condenser ; Stopping an, 35. 
 Engine equipped with Induction Condenser; 
 
 Stopping and starting an, 51. 
 Engine equipped with Jet Condenser; 
 
 Starting and stopping an, 33, 35. 
 Evaporation ; Condensing by means of, 26. 
 
 Feed-water Temperature when Condens- 
 ing ; L,oss in, 14. 
 Flooding due to Induction Condenser ; Pre- 
 vention of, 50. 
 
 Head and Pressure of Water; Relation 
 between, 2. 
 Heat. Effect of— upon a vacuum, 7. 
 Heat in a Pound of Steam, 54. 
 Heat Units required to convert Water into 
 Steam, 52-54. 
 
 I nduction Condenser , The, 47-51. 
 Induction Condenser , Adjustment of, 49. 
 Induction Condenser; Arrangement of, 48. 
 Induction Condenser ; Prevention of flood- 
 ing due to, 50 
 
INDEX. 
 
 79 
 
 Induction Condenser; Stopping and start- 
 ing an engine equipped with an, 51. 
 Injection Main ; Size of, 67. 
 Injection ; Starting a balky, 34. 
 Injection Water Supply, 44, 
 Injector Condenser ; The, 24, 25 and 41-46. 
 Injector Condenser ; Advantages of, 45. 
 Injector Condenser ; Arrangement of, 43. 
 Injector Condenser ; Diagram of 42. 
 
 V et Condenser ; The, 28-35. 
 
 Jet Condenser ; Arrangement of, 29. 
 
 Jet Condenser; Starting and stopping an 
 engine equipped with an indepen- 
 dent, 35. 
 
 Jet Condensers ; Types of, 30. 
 
 K 
 
 n o w 1 e s Horizontal Double- Acting 
 Pumps ; Table of, 71. 
 
 Lift of Water by Vacuum, 6-7. 
 Ivaidlaw-Dunn-Gordon Horizontal Double- 
 Acting Pumps ; Table of, 72. 
 
 M 
 
 I easurement of Atmospheric Pressure, 3. 
 Measurement of a Vacuum, 4-5. 
 Motor-Driven Pumps, 40. 
 
 I^ressure ; Absolute, 9. 
 
 Pressure and Temperature ; Relations be- 
 tween, 8-9. 
 
 Pressure of a Column of Water, 2. 
 
 Pressure of the Atmosphere, 3. 
 
 Pump ; Air. See Air-pump. 
 
 Pump Displacement required for Water to 
 Condense, 57. 
 
 Pump ; Circulating, 39-40. 
 
 Pump Rating, 61. 
 
 Pump Suction, 6-7. 
 
 Pump Tables ; See tables of pump data. 
 
 Pumps ; Motor-driven, 40. 
 
 Pumping Air, 10. 
 
 Pumping Hot Water, 7-8. 
 
 f"l elief Valves, 31. 
 
 Starting and stopping an engine equipped 
 with Induction Condenser, 51. 
 
 Starting an engine equipped with a Jet Con- 
 denser, 33. 
 
 Steam below Atmospheric Pressure ; Tem- 
 perature of, 8. 
 
 Steam ; Heat, in a pound of, 52. 
 
 Steam ; Heat required to convert water 
 into, 52-54. 
 
 Steam ; Physical properties of, 53. 
 
 Steam ; Water required to condense, 15, 16 
 and 55-57. 
 
 Stopping an engine equipped with a Jet 
 
 Condenser, 35. 
 Surface Condenser ; The, 23 and 36-40. 
 Surface Condenser ; Air-pump for, 65. 
 Surface Condenser ; Area of cooling surface 
 
 in, 65-66. 
 Surface Condenser ; Details of the, 37-38. 
 Surface Condenser ; Sectional view of a, 37. 
 Snow Horizontal Double-Acting Pumps ; 
 
 Table of, 73. 
 
 I ables of Pump Data : 
 
 Barr Horiz. Double-Acting, 77. 
 Conover Vert. Single-Acting, 69. 
 Dean Bros., Horiz. Double-Acting, 70. 
 Dean Bros. Twin Cylinder Vertical 
 
 Single-Acting, 76. 
 Deane Horiz. Double-Acting, 75. 
 Knowles Horiz. Double-Acting, 7:. 
 I,aidlaw-Dunn-Gordon Horizontal 
 
 Double-Acting, 72. 
 Snow Horiz. Double-Acting, 73. 
 Worthington Horiz. Double-Acting, 
 74- 
 Temperature and Pressure ; Relation be- 
 tween, 8-9. 
 Temperature and Vacuum ; Relation be- 
 tween, 68. 
 Temperature of Feed- Water when Condens- 
 ing, 14. 
 Temperature of Steam below Atmospheric 
 
 Pressure, 8. 
 Tower ; Cooling, 26. 
 
 Vacuum and Temperature ; Relation be- 
 tween, 68. 
 Vacuum Breakers. 31-32. 
 Vacuum ; Effect of heat upon a, 7. 
 Vacuum ; lifting water by means of a, 6-7. 
 Vacuum ; Measurement of a, 4-5. 
 Vacuum produced by Condensation, ir. 
 Valves ; lifting or clattering of air-pump, 
 
 27. 
 Valves ; Relief, 31. 
 
 W ater Column ; Pressure of a, 2. 
 
 Water to Condense ; Pump displacement 
 required for, 57. 
 
 Water ; Feed. See Feed water. 
 
 Water lifted by means of a Vacuum, 6-7. 
 
 Water ; Pumping hot, 8. 
 
 Water required per Horsepower for Con- 
 densing, in gallons, 67. 
 
 Water required to Condense Steam, 15-16 
 and 55-57. 
 
 Water into Steam ; Heat units required to 
 convert, 52-54. 
 
 Water Supply ; Injection, 44. 
 
 Worthington Horizontal Double-Acting 
 Pumps ; Table of, 74. 
 
THIS BOOK IS DUE ON THE LAST DATE 
 STAMPED BELOW 
 
 RENEWED BOOKS ARE SUBJECT TO IMMEDIATE 
 RECALL 
 
 LIBRARY, UNIVERSITY OF CALIFORNIA, DAVIS 
 
 Book Slip-50m-12,'64(F772s4, 
 
361847 
 
 Low, F.R. L9 
 
 Condensers. 
 
 LIBRARY 
 
 UNIVERSITY OF CALIFORNIA 
 
 DAVIS