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Questions and Answers from the American Machinist
Questions and Answers from the American Machinist Author:Frank Richards Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: Pumps and Hydraulics. 273. Q.—Supposing I have a pump that will discharge 100 gallons a minute and throw it 100 feet high. The piston speed is 100 feet per mi... more »nute, and the steam pressure 100 pounds, throttle valve wide open. At what hight will the same pump throw the water when running with a piston speed of 75 feet per minute, and discharging 75 gallons per minute? A.—The hight to which the water will be thrown will vary under the given conditions as the square of the piston speed. The square of 100 is 10,000, and the square of 75 is 5,625; hence we have: 10,000 : 5,625 :: 100 : x. This gives a value of 56.25 for x, which is the hight to which the water will be thrown with a piston speed of 75 feet per minute. 274' Q.—I have to attend to some two-throw pumps which work very badly and wear out the gearing very quickly. The depth of the well is 160 feet; the air vessel is at the top of the well; stroke of pump, 9 inches; diameter of barrel, 5 inches. I advised that the air vessel should have been placed as near to the pump as possible, and ordered this to be done. In the meantime an old- established firm who made the pump were consulted, and informed us that it is quite immaterial whether the air vessel is next to the pump or not, and that it is generally placed near the pump for convenience; consequently my order was countermanded, and I was further sat upon by being told that the practical view agrees with the theory. Who is right? A.—The information given by the manufacturers needs considerable modification. Although a foot or two in the position of the air chamber from the pump does not make any practical difference, the position is by no means a matter of convenience. On general principles the air chamber should be as close as possible to the pump, because when the...« less