SPRAY IRRIGATION. 



39 



having capacities of 50 to 100 gallons per minute range in cost from 

 $3 to $1 per gallon per minute capacity. Larger pumps of the duplex 

 and triplex types range as low as $1 per gallon per minute capacity. 

 These cost figures are for surface displacement pumps and do not 

 apply to deep-well equipment, which must vary according to local 

 requirements. 



The cost of centrifugal pumps is less than that of displacement 

 pumps having the same capacity, but the same general rule holds 

 that the smaller the pump the greater the cost per unit capacity. It 

 seldom is feasible to use a centrifugal pump for spray irrigation 

 where the requirement is less than 125 gallons per minute. The cost 

 can be assumed to range from $1.25 per gallon per minute capacity 

 for the small pumps to 10 cents per gallon per minute capacity for 

 large pumps. The figures are for horizontal high-pressure cen- 

 trifugal pumps for belt or direct drive and do not apply to vertical- 

 shaft or deep-well turbine pumps, the cost of which varies according 

 to local requirements. 



Pumps are made in definite sizes, each size having an economic 

 capacity. The irrigation system should be designed to fit some 

 standard-sized pump, so far as possible, in order to make the most 

 economical installation in first cost and in operation. 



Table 9. — Range in prices per horsepoiver for electric motors. 



Horsepower. 



Alternating current . 



Direct current. 



High 

 speed 

 per horse- 

 power. 



Low 

 speed 

 per horse- 

 power. 



High 

 speed 

 per horse- 

 power. 



Low 

 speed 

 per horse- 

 power. 



1 



$41 

 14 

 14 

 12 

 11 

 9 



$81 

 35 

 27 

 20 

 20 

 18 



$48 

 23 

 20 

 15 

 13 



$54 

 26 

 23 

 16 

 16 



5 



10 



30 



25 



35 









The cost of gas and oil engines varies according to type, materials 

 of construction, surface finish, ignition system, fuel equipment, etc. 

 In the case of engines built for gas and the lighter oils, like gasoline, 

 kerosene, etc., the four-cycle engines usually are much heavier than 

 the two-cycle, and their cost ranges somewhat in proportion. Four- 

 cycle engines of this type may be estimated at a cost of $25 to $40 

 per horsepower, while two-cycle engines range from $18 to $25 per 

 horsepower. Heavy oil engines are built in greater weight, regard- 

 less of cycle, and their cost should be estimated from $10 to $50 per 

 horsepower. 



For estimating purposes electric motors may be divided into two 

 general classes, those running on alternating current and those run- 



