





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 horsepower for electric motors. 






Alternating current.| | Direct current. 
Horsepower. High Low ‘High Low 
speed speed speed speed 
per horse-| per horse-| per horse-] per horse- 
power. | power. power.}| power. 
LT eats Ci et $41 $81 $48 $54 
GT eS NPP mice teehee 14 35 23 26 
IU) ee tt secrete age Te 14 27 20 23 
BO ees cee A Nn he 12 20 15 16 
DARE ors es NO rane tate en pT 11 20 13 16 
DO Ce econ aE ene 9 LS eS SET ec eon ie ene ge a 


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 $40 to $50 per 
horsepower. 
For estimating purposes electric motors may be divided into two 
general classes, those running on alternating current and those run- 





