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Engineering Data Bulletin 90 www.cranepumps.com Engineering Data Table 25 Useful Information Area of a circle - diameter squared x .7854. Atmospheric pressure at sea level is usually estimated at 14.7 pounds Circumference of a circle - diameter x 3.1416 per square inch, and this pressure will maintain a column of water Pressure in pounds per square inch of a column of water - head in feet 33.9 feet high when the normal pressure in the column is relieved by x .433. the creation of a vacuum. This is the theoretical distance that water Head in feet of a column of water - pressure in pounds per square inch may be driven by suction. In practice, however, pumps should not x 2.30947. be placed over 20 to 25 feet above the water supply, and nearer if A U.S. gallon - 231 cubic inches. possible. A U.S. gallon of fresh water weighs 8.33 pounds. Brake horsepower is obtained from the formula: A U.S. gallon of sea water weighs 8.547 pounds. GPM x Head in Feet of Liquid x Specifi c Gravity An Imperial gallon - 277.274 cubic inches. 3960 x Effi ciency of Pump An Imperial gallon of fresh water weighs 10.005 pounds. or An Imperial gallon of sea water weighs 10.266 pounds. GPM x Pounds per Square Inch A Cubic foot of water (1728 cubic inches) contains 7.481 U.S. gallons 1714 and weights 62.355 pounds. NOTE - It is standard practice to give head in feet, not in pounds, per square inch when refer- ring to centrifugal pumps. For reciprocating pumps, pounds per square inch is always used. Doubling pipe diameter quadruples the capacity. Friction of liquids in pipes increases as the square of its velocity. K W Hours per 1,000 gallons of cold water per hour is obtained from A Minez's inch of water is approximately equal to 11½ U.S. gallons per the formula: minute. Total Dynamic Head in Feet x .00315 Areas of circles are to each other as the squares of their diameters. Motor Effi ciency x Pump Effi ciency Total head is the sum of the static head and the pipe friction. Table - Weights and Measures U.S. Standard Metric System Liquid Measure Liquid Measure 1 pint 47.3171 centiliters 1 centiliter .0211 pint 1 quart .9563 liter 1 liter 1.0567 quarts 1 gallon 3.7854 liters 1 hectoliter 26.4176 U.S. gallons Weight Weight 1 pound .4536 kilogram 1 kilogram 2.2046 pounds 1 ton (2000 lbs.) 907.2 kilograms 1 tonneau 2204.55 pounds Length Length 1 inch 2.5309 centimeters 1 millimeter .0394 inch 1 foot 30.4794 centimeters 1 centimeter .3937 inch 1 yard .9143 meter 1 meter 39.3708 inches 1 mile 1.6093 kilometers 1 kilometer .6214 mils Square Square 1 sq. inch 6.4513 sq. centimeters 1 sq. centimeter .1549 sq. inch 1 sq. foot .0929 sq. meter 1 sq. meter 10.7631 sq. feet 1 sq. yard .8361 sq. meter 1 are 119.5894 sq. yards 1 acre .4047 hectare 1 hectare 2.4711 acres Cubic Cubic 1 cubic foot .02831 cubic meter 1 cubic meter 35.3166 cubic feet Table - Comparative Equivalents of Liquid Measures and Weights Measure and Weight Equivalents of Items in First Column Measures and Weights U.S. Imperial Cubic Cubic Cubic for Comparison Liter *Vedro *Pood Pound Gallon Gallon Inch Foot Meter U.S. Gallon .................................... 1. .833 231. .1337 .00378 3.785 .308 .231 8.33 Imperial Gallon .............................. 1.20 1. 277.27 .1604 .00454 4.542 .369 .277 10. Cubic Inch ...................................... .0043 .00358 1. .00057 .000016 .0163 .00132 .001 .0358 Cubic Foot ..................................... 7.48 6.235 1728. 1. .02827 28.312 2.304 1.728 62.355 Cubic Meter ................................... 264.17 220.05 61023. 35.319 1. 1000. 81.364 61.023 2200.54 Liter ................................................ .26417 .2200 61.023 .0353 .001 1. .08136 .06102 2.2005 *Vedro ............................................ 3.249 2.706 750.1 .4344 .01228 12.29 1. .7501 27.06 *Pood ............................................. 4.328 3.607 1000. .578 .01636 16.381 1.333 1. 36.07 Pound ............................................ .12 .1 27.72 .016 .00045 .454 .0369 .0277 1. SECTION 90 PAGE 30 DATE 9/07 A Crane Co. Company USA: (937) 778-8947 • Canada: (905) 457-6223 • International: (937) 615-3598 Engineering Data www.cranepumps.com Bulletin 90 Engineering Data Table - 26 Simple and Accurate Method of Measuring Pump Capacity (Reprinted from The Journal by the permission of the copyright holders, Edward E. Johnson Inc.) Measuring the Discharge Instructions For Using Orifi ce Water Meters Description of Apparatus There are a number of common methods of determining the yield of a well. Weirs are most commonly used for this purpose, The channel or pipe of approach, at which one end of the but there are a number of objections to the use of weirs, chief orifi ce is attached, should be at least 6 feet long over all. two among which are the Inconvenience, cost, and trouble of feet back from the end to which the orifi ce plate is attached, constructing and setting up an accurate weir; and very this discharge pipe should be tapped for ⅛ inch pipe. All burrs, uncertain results are sure to follow unless the weir is carefully as a result of making this tap, should be carefully fi led off on made and set up. A commercial fl ow meter is the most the inside of the pipe. A ⅛ inch pipe nipple should be screwed accurate measuring device, and it it very simple to use; but a into this hole and should be fl ush with the inside of the pipe. good commercial fl ow meter is expensive equipment for a well driller to have on hand, especially since more than one size The small tube in which the head of water is measured is might be required. called the Piezometer Tube and consists of a 5 foot length of rubber hose with a short section of glass tube fastened at one There is a very simple, inexpensive and yet accurate method end and the opposite end attached to the ⅛ inch pipe nipple which was extensively experimented with at Purdue that is screwed into the discharge pipe. See Fig. 1. The water University, where different sizes were calibrated to an accuracy level in the Piezometer Tube is kept visible in the glass by of approximately 2% - which is much more accurate than the raising or lowering the end of the rubber hose. average well-constructed fi eld weir. This method of measuring the discharge is called a Circular Orifi ce Flow Meter. It consists The discharge pipe must be supported in a horizontal 1 of a circular steel plate, /16 inch thick, which is centered over position using a level to make sure it does not slant, and the the end of a discharge pipe, and in which there is a perfectly Piezometer connection must be in a straight line out from it circular hole with clean square edges, smaller in diameter than when readings are taken. The pressure head on the orifi ce the discharge pipe; and back two feet from this plate a small is measured as the vertical (up and down) distance from the pipe (⅛") tapped smoothly at right angle into the discharge level of the water in the Piezometer Tube down to the center pipe at the horizontal center line. the sketch (Figure 1) shows of the orifi ce opening. The discharge pipe may be connected how this is assembled. to the pump discharge by means of pipe connections, rubber SECTION 90 PAGE 31 DATE 9/07 A Crane Co. Company USA: (937) 778-8947 • Canada: (905) 457-6223 • International: (937) 615-3598 Engineering Data Bulletin 90 www.cranepumps.com Engineering Data or canvas hose or other means which will conduct the water to 7. The upstream edge of the hole in the orifi ce plate should the orifi ce and yet permit the orifi ce and channel of approach to have a sharp edge and the thickness of the plate be held in a rigid horizontal position. Water should be allowed surrounding the hole should be 1/16 inch. (See Fig. 3). The to fl ow freely out of the Piezometer Tube until measurements hole should be bored to accurate measurements. are taken. This will eliminate any obstruction such as sand, air 8. Channel of approach, back of orifi ce, must be full of water to bubbles, or other material from the tube line. A thread protector give accurate measurement of fl ow. is a convenient means of holding the orifi ce plate on the end of 9. It must be remembered that when testing a pump meter with the pipe. an orifi ce, the head as measured by the Piezometer from the center of the channel of approach to the level of the Factors Infl uencing Accuracy of Results water in the Piezometer Tube, must be added to the head from the center of the approach channel to the water level 1. The channel of approach must be horizontal (level). in the well to determine accurately the head the pump is 2. The Piezometer Tube (⅛ inch pipe) must be fl ush with the working against. inside of the discharge pipe and free from burrs on the inside at this point. To illustrate this: If the pumping level in the well was 50 feet 3. The discharge from the orifi ce must fall free. from the center of the outlet pipe or channel of approach, and 4. The head on the orifi ce must be suffi cient to cause a clear the head on the orifi ce was 60 inches, the total head that the fl ow.
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