Practical irrigation by Bowie Aug. J. (Augustus Jesse)

Author:Bowie, Aug. J. (Augustus Jesse)
Language: eng
Format: epub
Tags: Irrigation
Publisher: New York, McGraw publishing company
Published: 1908-03-25T05:00:00+00:00

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PUMPS AND PUMPING MACHINERY.

106

Column 1 gives ft. lift X cu. ft. per sec.

Column 2 gives ft. lift X gal. per min.

Column 3 gives water horsepower at 100 per cent efl&ciency.

Columns 4 to 16 give engine horsepower at various eflBciencies.

To lift 1 acre-foot of water 1 foot requires the expenditure of 1.37 water horsepower-hours. This may be conveniently used in calculation of total quantities of energy required in the irrigation of land. To illustrate the use of Table IX, what horsepower engine must be provided to lift 700 gal. per min. a height of 70 feet, the friction and other losses in piping being 20 feet, with a pump of 60 per cent efficiency. The total head is 90 ft., and 90 X 700 « 63,000. Looking under the second column, 6330 gal. per mm. X ft. require at 60 per cent efficiency 2.67 horsepower. Hence, required power of the engine = 26.6 horsepower.

In consideration of the lift of the pump there is often some confusion with regard to the exact meaning of this term. Distinction must be made between the lift of the pump and the total head against which the

pump must operate. The head is equal to the lift, plus all the losses in friction, entrance to pipes, curves, and discharge from the outlet of the piping. The ratio of the lift to the head we shall call the efficiency of the piping. To illustrate this, in Fig. 25, let

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