PUMPS 519 
805, p. 503, the area of the piston-rod being half that of the piston. ‘Then 
construct the rate of delivery ram for two such pumps driven through cranks 
at right angles to one another, Take the length of the connecting-rods equal 
5 cranks 
to . 
10, A “three-throw ” deep well pump has three pistons each 6 inches diameter, 
with piston-rods 2 inches diameter, Stroke of each, 24 inches. The pistons are 
driven through a crank shaft having three cranks making 120° with one another. 
The connecting-rods are so long that the pistons may be assumed to have 
harmonic motion. Draw the rate of delivery diagram for this pump. 
11. A centrifugal pump with vanes curved back has an outer radius of 10 
inches and an inlet radius of 4 inches, the tangents to the vanes at outlet being 
inclined at 40° to the tangent at the outer periphery. The section of the wheel 
is such that the radial velocity of flow is constant, 5 feet per second ; and it 
runs at 700 revolutions per minute. Determine, (1) The angle of the vahe at 
inlet so that there shall be no shock, (2) the theoretical lift of the pump, (3) the 
velocity head of the water as it leaves the wheel. [U.L.] 
12. Determine the circumferential speed of the wheel of a centrifugal pump 
which is required to raise water to a height of 5 feet, having given that the 
efficiency is 0°6. The velocity of flow through the wheel is 4°5 feet per second, 
and the vanes are curved backwards so that the angle between their directions 
and a tangent to the circumference of the wheel is 20°. 
13. A centrifugal pump 4 feet diameter, running at 200 revolutions per minute, 
_ pumps 5000 tons of water fromi a dock in 45 minutes, the mean lift being 20 feet. 
The area through the wheel periphery is 1200 square inches, and the angle of 
the vanes at outlet is 26°. Determine the hydraulic efficiency, and estimate the 
average horse-power. Find also the lowest speed to start pumping against the 
head of 20 feet, the inner radius being half the outer, [U.L.] 
