NEW PUMPING ENGINE AT MADISON

NEW PUMPING ENGINE AT MADISON

(Specially Written for FIRE AND WATER.)

The duty test of the new pumping engine at the waterworks station of Madison, Wis., took place at the end of January, 1902. It lasted only two hours, instead of twenty-four, owing to insufficiency of water furnished by the wells—this insufficiency being largely due to the large quantities of air which leaked into the suction-pipes. The test was made when the reservoir was entirely full, so that the pump might draw its water at least partially from that source, which would afford water for between two and three hours only. The engine was run at stub a speed as should come up as nearly as possible to that of the contract. By that was demanded a duty of 125,000,000 foot-pounds per one thousand pounds of dry steam furnished to the engine at 125 pounds pressure—the engine running at fifty revolutions per minute, and the capacity of the pump bing 3,000,000 gallons per twenty-four hours. Several preliminary tests had been made before the final test, and at these it had been found impossible to run the engine at a higher/speed than about thirty-five revolutions per minute As will be seen, however, at the test proper the average speed of the engine was 39.3, or 10.7 per minute less than the contract called for. During the test three engineering students front the University of Wisconsin were present under Mayor Storm Bull, professor of Steam Engineering in that university, who conducted the test. One took indicator cards from the three cylinders. as well as the necessary observations at the separating calorimeter, which were to serve to compute the moisture in the steam. A second weighed the condensed water from the engine; the third made the necessary observations on the pressure gauge. The engine was run about one half-hour before the test began, and on inspection was found to be in perfect order, as was the testing apparatus. During the two hours’ test 2.590.5 pounds of condensed steam was weighed out from the engine; the calc 1meter showed that the average quality of steam was ,96665; consequently, the number of pounds of dry steam used by the engines was 2,590.5 multiplied by 96665, which gives 2,504.1 pounds of dry steam. The average head during the test counted from the vacuum in the suction-pine to the pressure in the discharge-pipe was 211.3 feet. The total number of revolutions was 4,718; area of the three plungers in the pump together is 405.9 square inches; stroke of the pump, twenty-four inches. The weight of one cubic foot of water is 62.4 pounds, consequently, the duty expressed in foot-pounds per 1,000 pounds of dry steam was:

Duty= 405.9*24*4718*211.3*62.4/(1728*2.504)

The duty of, the engine during the two-hour test was, therefore, a little above 140,000,000, or 15,000,000 above what was called for. The total number of revolutions, as already stated, was 4,718; the average pressure at discharge was 81.04 pounds; average vacuum in suction, 7-3$ inches mercury; average steam-pressure, 125.8 pounds. The readings were taken every five minutes. According to the calorimeter the nounds of steam used were as follows: 5.02, 5.10, 5.05, 5.05, 5.05, 5.20, 5.10; pounds of water separated: .175, .180, .170, .170, .171, .183, .175: per cent, of water: 3.39, 3.4, 3.26, 3.26, 3.26, 3.46, 3.32; time: 12:20, 12:37, 12:55, 1 :i5, 1:30, 1:45, 2:00— the average per cent, of water was 3.335 per cent; weight of condensed steam—total: 432.5, 450.0, 439.0, 440.5, 447.5, 446.5, 307.0, 300.0; tare—82, 85, 84.5, 84.5, 83.0, 85, 84, 84.5; net—350.5, 365.0, 354.5, 356.0, 364.5, 361.5, 223.0, 215.5—total steam condensed, 2,59°-5 pounds, of which 96,665 per cent, was dry steam, or, in all, 2,504.1 pounds of dry steam. The calorimeter used was one of Carpenter’s separating calorimeters, which had been thoroughly standardised in the steam engineering laboratory of the University of Wisconsin. Readings of this calorimeter were taken seven times during the test. It was attached next to the throttle-valve of the engine, the sampling pipe extending more than half-way through the steam pipe. The condensed steam was lifted by the air-pump through a temporary pipe connection up into one of two barrels, from which it was run into another barrel placed on a scale where the water was weighed. The lower barrel was nearly filled eight times. As to the calibration: The pressure gauges and vacuum gauge had been calibrated previously to the test in the laboratory of the university, and were found to be correct. Because of the position of the gauges and the places of connection of the same with the discharge and suction-mains, the actual head against which the water was pumped was 211.3 feet.

THE PUMPING STATION, MADISON, WIS.THE NEW PUMPS COMPLETE, MADISON, WIS.

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