The Brooklyn Pumping Engines of 1860.

The Brooklyn Pumping Engines of 1860.

Conclusion.

There is an important distinction between the upper and lower faces of any pump piston in action. While the load on the upper side is the entire mechanical water lift, and depends on the relative level of the piston, below the piston the atmosphere makes the lift, and the resistance is a simple question of vacuum formed; and this is to an important extent independent ot the relative height of the piston above the water, and shows the necessity of engine inertia to prevent too rapid a start.

The law of vis vivo, by which the resistances are reduced instead of increased in the water column in motion as its lift increases, is shown in the annexed cards (Figs. 20, 21 and 22).

In the first card, the conditions of free delivery to the plunger barrel are very favorable, since there is a water head of 3.5 feet, and very large valves, with a short passage from the forebay; yet from too rapid motion or other cause, to start the column and maintain its flow, the indicator opeiis with a vacuum of over 3 lbs.; at the first foot, 6.25 lbs.—average, 4.25 lbs.; showing at the first foot a vacuum equal 14.37 feet lift under an actual load of 2 feet, and at the end of the stroke the vacuum is 2 lbs. or 4.6 feet, when the actual lift is 6 feet above the well. The pump might have been about 15 feet higher with so much less water load.

In the second card (also a plunger, single acting) it is evident, as the velocity water stroke of the first engine shows, that there is a lack of counterweight. Here the vacuum is 8 lbs., or 18.4 feet lift, against 8.15 actual; at the first foot, 24.15 feet against 9.15; at the end. 4 lbs, or 9.2 feet, where the actual lift is 19.07 as the vis viva effect of the column; and the mean vacuum is 9.34 lbs., or 21.48 feet, against 13.61 actual, another waste of power.

In the third card the upper pump dees its work about 1.39 lb. per square inch less than the lower, which starts with a bucket load of about 3 feet. The lift is 10.58 feet, and the vacuum 17.25 at the start; at one foot pull, 20.7 feet; lift, 11.58; final null, 6 lbs., or 13.8 feet, with an actual lift of 20.45, 8 9 lbs; mean lift, 15.51 feet; vacuum, 17.52.

This engine was doing nearly five limes the work of the second, and the economy of pump position is clearly shown, involving a gain peculiar to this form of engine.

The Hartford and Cambridge pump cards show similar action (Figs. 23, 24, 25).

In these pump cards the same law of vis viva developed by air pressure is proved in direct mass pressure or steam.

In addition to cards given, the following have certain important bearings;

The Belleville counterweight (standpipe), without air-chamber relief, opens the card with a load of 66.5 lbs., or 153 feet lift, against an actual of 139.76; the surplus work then reduces the load to a final resistance of about 60.5 lbs., or 139 feet, the actual being 150.68.

With all its care in design and reciprocal pump relief, but with 4 pumps acting on the same 12-inch miin, the Hartford pump opens with 61 lbs., or 140.5 feet lift, against an actual of in.76, or 48.6 lbs.; the wave reduces the load to 49 lbs. at the close, or 112.7 feet. against an actual ol 110.43.

The Cambridge horizontal pump, opening with a partly unfilled chamber, and without much weight, strikes solid water with a blow of 41 lbs., which includes some spring vibration, against 27.8 actual, and ends with 32.

In these, and abundant other cards, the same law of wave generation, acceleration and retardation is demonstrated in full confirmation of theory. What is true of the cylinder card is true also of the pump card under a fixed law.

In further demonstration of the modifying effects of counterweight and air cushion on the pump wave, the following average card, taken in the capacity (Brooklyn) test, with about lo^ strokes per minute is given (Fig. 26). While the same want of weight is shown in the initial blow, the rapid reduction of reaction is also shown, and the return control of the air chamber (which absorbs part of the intial work) tends to equalize the wave motion, the practical reduction of final resistance being about 4}⅛ pounds; the air chamber in this case acting on the main, in its turn, to propel the wave from the power stored in it at the beginning of the stroke.

Engine No. 2, after the acceptance of No. 1, was built substantially a duplicate, except that the cylinder bore was 85 inches the capacity of the counterweight chests was enlarged (though not properly used), the valves of each annular pump barrel were changed to 8 double beat foot valves, instead of one upper 54-inch (without any special gain), with some minor changes. It was tried May 21, 1861, and tested February, 1S62; duty reported being 619.037 foot-pounds.

My resignation being made in i860, the engine was not built under my charge, and like No. 1, it never was properly loaded, being worked with low steam and a throttle.

It has been stated at various times that these engines were patented by Mr. Wright. The annular pump barrels were patented by him in 1859; •he diaphragm and some parts of the valve motion were his inventions; but the engine itself, as a combination of counterweighted, double acting pumps, with double beat valves on the rods, was not his improvement, and not patented.

Prospect Hill engine was built with a fly wheel, with two lifting pumps worked from the beam; 4.5 feet cylinder by 34 inches; pumps. 41 inches by 20; boiler, double return drop flue, 18 feet by 6 feet beam. It takes its supply from the 36inch city main, at the corner of Underhill avenue and Warren street; engine room floor level, 119.5 above tide; reservoir flow line, 197 feet above; (ceding main at pumps, about 106 feet.

BROOKLYN PUMP MAIN; VELOCITY CARDS.

The action of the pumps under trial was defective; with 50 jiounds steam and one-fourth to one-fifth cut off. the duty was limited to 500,000 foot-pounds. Mr. Wright, therefore, put in a new set. with easy entrance and delivery lines, with a large air chamber on the supply, embarrassed by surplus pressure. This brought the engine up in duty, so that under test of May, 1862, it made 649,577 foot-pound* as reported, “parallel” coal estimates being used on 93 hours run.

Engine Experiments.—During the winter of 1857-58, trials were made of the Belleville, Hartford and Cambridge engines. The results are collated in the following table. Messrs. Worthen. Copeland, Graff and Morris were in charge :

PUMPING ENGINE TESTS.

* Parallel estimates used; results in question.

Annual Operation—The engine house anti its appurtenances, under the original contract provided for four engines, each of not less than 15,000,000 per day. The average consumption of 1889 was 52.9l.t38; the maximum, December, 55,112,699 gallons. With four superb engines working side by side, two of which could easily have been enlarged to lift 20,000,000 each, this engine bouse would have had no parallel; but the provisions of the original plan have been neglected. In the main room there arc now three engines; In a side room cxcrcscnce, built on the front, there are four horizontal “ Davidson ” engines 10 do the work of one ; and in a very costly engine house on the aqueduct, several hundred feet south, two vertical compound ” Worthingtons” are being completed. Engines Nos. 1 and 3, under the charge of a man who believed in crank cemres and throttling, and cared little for duty, did their work quietly and regularly, with remarkably light repair accounts. In 1866 No. 1 ran 3824 hours : engine repairs, $160.22 ; No. 3, 3066 hours; repairs, $171.84.

In 1866 Brooklyn began an extravagant system of water expenditures in various directions, under which, during 30 years’ supply, with a revenue of $26,645,902, the outlay has been for operation and maintenance, $9,543,000; interest, $16,698,000; original construction, $5,440,000; extensions, about $11,620,(xx>, or about $43,301,000.

In 1866 a full coat of ashes for the boilers was replaced by an expensive felt cover. In 1867 the 15-inch beam pin was enlarged to 20, and a new pump head made for No. 1. In 1868 an 80 inch cylinder was ordered as a substitute for No, j, 90 inch, and a new set of pumps at $27,000. In 1870 its altera, tiotr to a crank engine was decided. In 1871 three new boilers were set, though the other three were in use in 1885.

Of No. 2, the report for 1873 says : “ With the exception of new hrasses to the beam pillow blocks, and new valves to the pumps, no repairs sre anticipated on this engine,” In 1881 No, 2 ran 7420 hours ; in 1SS6, 7198 ; 1889, 8149. A continuous service of 30 years is shown by this engine of t86t.

These engines cost $138,000; No. 3, of 1869, $129750; No. 4, 1883, with building and main, $127,398 ; net, $70,000; No. 5, 1888, 2 engines, 10,000,000 gallons each. $190,471 ; house very expensive.

No. 3, as tested, had 178.43 feet lift (No. 1, 170 feet), 7# per cent loss of action (No, I, 169); could not be continuously run; credited with 683,872 ft. lbs.; duty ot 1874 590,876; repair bill, 1872. $57

No. 4. lift, 179.21 feet ; duty, by capacity of pump, 657,561 ft. lbs.; 1886, 550,988.__

THE STORY OF THE Obelisk.—At Heliopolis was the Temple of the Sun. and the schools which Herodotus visited because the teachers are considered the most accomplished men in Egypt,” When Strabo came hither, 4 years later, he saw the house which Plato had occupied ; Moses here learned ‘all the wisdom of the Egyptians.” Papyri describes Heliopolis as “ full of obelisks.” Two of these columns were carried to Alexandria 1937 years ago, and set up before the Temple of Cxsar. According to one authority, this temple was built by Cleopatra ; in any case, the two obelisks acquired the name of Cleopatra’s Needles; and though the temple itself in time disappeared, they remained, where they had been placed—one erect, one prostrate—until in recent years one was given to London and the other to New York. One recites all this in a breath in order to bring up, if possible, the associations which rush confusedly through the mind as one stands beside this red granite column rising alone in the green fields of Heliopolis. No mylh itself, it was erected in days which are to us mythical—days which are the jumping oft place of our human history ; yet they were not savages who polished this granite, who sculptured this inscription; ages of civilization of a certain sort must have preceded them. Beginning with the Central park, we force our minds backward in an endeavor to make these dates” real. “Homer was a modern compared with the designers of this pillar,” we say to ourselves. The Myceme relics were articles de Paris of centuries and centuries later. But repeating “the words (and even rolling the r’s) are useless efforts ; the imagination will not rise ; it is crushed into stupidity by such a vista of years. As reaction, perhaps as revenge, we flee to geology and Darwin; here, at least, one can take breath.

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The Brooklyn Pumping Engines of 1860.

0

The Brooklyn Pumping Engines of 1860.

(Continued.)

There were three boilers for each engine in a side wing, with chimney arranged for supplying two engines; shells, 8 feet diameter, 30 feet long; steam drums, 4 feet diameter by 4 feet each; two furnaces, 6 feet 3 inches deep by 3 feet inches wide; doors fitted for air supply; four upper flues, l8 1/2 inches diameter, 21 feet 9 inches long; lower returns. 8 1/2 inches diameter; 7 in upper row, 6 in next, 3 in lowest, return, under boiler, to chimney conduit, 4 feet square, in brickwork; set in brickwork, tops covered with ashes, fronts felled; grate surface, each, 37.5 square feet; fire surface, 13.55 square feet, 903 effective; combustion, January, 1860, 11.86 pounds per square foot; evaporation by tank (212 degrees), 9 95 (July, 1860); by volumes, 9.27 pounds per pound coal burned; Hartford boiler, 8.39 pounds; Belleville. Cornish boilers, 7.49.

Temperature experiments were made on the Hartford boiler of the same type to get flue action. Length 22.26 feet; diameter, 7.5 feet; grates, 25.5 square feet; fire surface, 910 square feet; effective, 608. Thermometer showed, under slow combustion, lowest return (floor), 160 to 180 degrees; side, 209 degrees; centre, 240 degrees; near shell, 284 degrees; back connection, 334 degrees; lower flues, 370 degrees; middle. 400 degrees; upper flues, 550 degrees. This shows a rapid conduction of heat in the upper flues from about 2000 degrees furnace, and in 14 feet 4 inches travel, and also in the successive lower returns. With steam at 280 degrees the lowest return at the shell and at the back end was not cooling it, but preparing the feed supply for its upward travel to the most effective and topmost level, furnishing a fine illustration of the double return drop flue theory already slated. The Brooklyn boilers, with 8 feet diameter and 30 feet length, gave higher evaporation under more rapid combustion.

DUTY Tests.—Engine No. I was embarrassed by being put under contract at $10,000 less than a fair price, as it was built, being a union of two different engines. The pro rata estimate for work in the shop was exhausted about December I, 1858, and the balance for erection was not large. Expensive changes in valve motion and otherwise occurred. While, then, the contractors made complete construction a matter of pride, much was conceded to them within the strict accomplishment of the contract duty.

In June, 1859, the engine had been brought up to a speed which established its capacity and best motion, and the 25th or 27th. a forty-eight hour duty test was made with a mean speed of 8.86 double strokes per minute and 425,000 footpounds duly. It had been run occasionally at 10¾ and 11 strokes, anti was used for daily city supply more or less.

The weight in motion, estimated, was, finished wrought iron. Piston buckets, etc., 72,000 pounds; counterweight chests, 19,000; beam (effective), 30000; water load (effective), 65.txio. Total, 186,000, of 243,000 calculated as required to secure proper action and expansion.

Some improvements being made September 15. the engine was tested 64.5 minutes, making 10,652 strokes per minute, with a duty of 487,500 foot-pounds,

A steam-jacket waste into the well, of about 30 lbs. coal used per hour, was relieved. Some improvements in valve motion and otherwise were made, and boiler steam was raised to 16 or 18 lbs. A du’y test of January 12 to 14, i860, with 9.57 strokes per minute, was 611,114 ft. lbs., and the engine was accepted.

DUTY Cards.—To illustrate the principles discussed in this paper, the following diagrams and cards are given.

Up to this time the maximum boiler pressure was about 9 lint., and the engine was not only throttled at the steam-chest, but also by the valve motion. Mr. Wright, therefore, conceded increased counterweight and higher steam ; and December 22 and 23, on 2SJJ hours’ run, with 9.342 strokes, the duty was 575.300 ft. lbs., with about 100 tons in motion.

BOILER Firing.—The objections to ” parallel” coal estimates, which assume that the value of the grate conten s can be determined by inspection, are shown by the firing record of the test of January, i860, as plotted (Fig. 5). In this case the coal charges were uniform as weighed, and used as the state of the grates required ; nothing like parallel times and quantities occurs.

The system specified in the contract was to put the fire room, boilers, engine and engine room at their usual working temperature ; then blow off steam and clean the grates. Then starting fires, running not less than 24 hours, charging all fuel used to the experiment less the value of grate contents, when the engine runs down on the last charge. By this process the fuel which has done the work is accurately weighed, and the contingencies of error are reduced to a minimum. Of course, a longer test wijl be more satisfactory, but is not usually con. vcnient. The Cornish system of taking all the coal used fora month reduces the actual coal duty for banked fires and similar losses.

The law by which an engine naturally reaches its maximum speed under due load and pressure, and the relative advantages of proper load to control the acceleration and retardation of speed in travel, are shown in the velocity cards from the Old Ford engine (Figs. 6, 7 and 8), the Spring Garden (Figs. 9, 10 and 11), and the Brooklyn No. 1 (Figs. 12, 13 and 14).

The maximum velocity in each case is attained within onethird of the stroke, but the form of the card is much superior in the Old Ford, with higher initial pressure, to the low, throttled pressure line of the Brooklyn. The effect on final pressure is very material as a comment on short counterweight in the latter, and the water card of the Spring Garden shows defective weight there. The prolongation of maximum speed early attained tends to increase final pressure and consequent steam use. The theory of uniform resistance is therefore improper, and the cut-off a mechanical necessity.

It is also demonstrated that improvement in initial stability of piston in pumping reduces mean resistance. Not only does the Old Ford card, opening with 29 lbs. steam, end with a full cylinder at 6.5, while the Brooklyn, with 19.7, ends with 10.2, but the cards of this and the model engine show reduced mean resistance with increased initial pressure, because working in harmony with the mechanical law of vis viva as to both engine and water mass. Another important gain is shown in the increased length of stroke due to better control of final motion, which gains in water delivered and in reduced clearance loss per stroke. In June the travel was generally 9.33 feet; in September, 9.66 to 9.75 feet ; in January, 9.875 ; and with additional load, to reduce final pressure, it could be made in 10.3 feet space, about 10.1 safely, with our carefully built spring beams.

The comparative steam cards of June 6, 1859, and January 12, i860 (Fig. 17), further illustrate the effect of increased weight on final pressure.

The pump card of January (Fig. i8)also shows the improvement on the card of September 15 (Figs. 15 and 16).

The direct harmony of the water column with the motion of the engine mass is shown by the annexed cards.

Water has four modes of motion, and each of these is a wave. The wave of the first order moves a group of particles forward—but not with its speed—by displacing successive sections, with a vertical or nearly vertical motion, as shown by the channel flow of tidal waves, lock outlets and other discharges; that of the second order carries the particles with the wave, as in streams and pipes; the third order has a circular or elliptic particle motion, where the wave progresses without the particles, as in sea swells and pond ripples; in the fourth order the wave is stationary and the particles move on, as in weir chutes, rapids, eddies, etc. These frequently act in conjunction.

A pump stroke produces the “forced” second order wave in a main, with more or less “ free ” displacement action; and each stroke tends to produce a distinct wave with its distinct motion; two or more pumps acting on the same main disturb this motion and react; a defective seating or motion of a valve produces reaction.

With a heavy incompressible, but very mobile liquid, to produce this wave properly, the column must be started with surplus initial pressure, and its maximum speed attained at an early period of the stroke; the power thus surcharged will complete the stroke under reduced pressure.

The distinct waves in motion in a main are effected by its diameter and line, and each main has a wave of maximum effect in capacity and speed; experience, even with hand pumps, makes this clear; our Brooklyn experience showed a gain in action up to a speed of about 200 feet per minute. In the Belleville tests, with slow speed, each pump wave was distinct in accelerated and retarded discharge at the reservoir overfall; in the Hartford main the flow continued fifteen minutes after the pumps stopped, with about 2936 cubic feet, or 152 pump revolutions discharge.

Our experiment with the diaphragm, which seriously reduced the working capacity of the air-chamber, like the Prospect Hill experience without a supply main air-chamber, showed a serious increase in water load and reaction. In that case the check valve, located 1952 feet from the engine and 49 5 feet above tide, closed at every stroke ; not so with the full airchamber on. This is shown by the velocity card of September 30, 1859 (-

There is an important distinction between the upper and lower faces of any pump piston in action. While the load on the upper side is the entire mechanical water lift, and depends on the relative level of the piston, below the piston the atmosphere makes the lift, and the resistance is a simple question of vacuum formed; and this is to an important extent independent of the relative height of the piston above the water, and shows (he necessity of engine inertia to prevent too rapid a start.

(To be Continued.)