B4D451 Pages: 3

b. A double acting reciprocating pump is fitted with an air vessel on suction side close
to pump. The suction lift of pump is 4.5m. The length and diameter of suction pipe
are 7.5m and 80mm respectively. The stroke of piston and its diameter both are
200mm each. Coefficient of friction is 0.01. The atmospheric head is 10.3m and
separation pressure head 2.5m of water absolute. Determine i) The speed at which
separation commence ii) Maximum permissible speed without air vessel. (6)

6. a. Prove from first principle that the work saved in a single acting reciprocating pump
by fitting an air vessel is 84.8%. (5)
b. The inlet and outlet diameter of impeller of a centrifugal pump are 40cm and 60cm.
The velocity of flow at outlet is 2.5m/s and vane outlet angle is 30°. Find the
minimum speed of the pump to start the flow. Take manometric efficiency as 75%.(5)

7. a. Explain the following:

i) Hydraulic Accumulator ii) Vane Pump (5)
b. Explain NPSH and Thoma’s cavitation factor in centrifugal pump (5)
8. a. Explain multistaging in centrifugal pumps. Where are they used? (5)

b. The impeller of a centrifugal pump is 1m in diameter and rotates at 1500rpm. The
blades are curved backward and make an angle of 30° to the tangent at the periphery.
Calculate the power required if the velocity of flow at outlet is 20m/s. Determine the
head to which water can be lifted when a diffuser casing reduces the outlet velocity
to

60%. (5)

PARTC
Answer any four questions.

9. a. How are compressors classified? List the practical applications of compressors. (4)
0. A single stage single acting reciprocating air compressor compresses 7x10 * 1108
air per second from 1.0132 bar to 14 bar. The index of polytropic compression is 1.3
and mechanical efficiency 82%. If clearance is 3% of the swept volume, determine

the volumetric efficiency and power required to drive the compressor and show the
process on P-v diagram. (6)

10. a. What is meant by surging and chocking in centrifugal compressors? (4)
b. A three stage single acting reciprocating compressor has perfect intercooling. The

pressure and temperature at the end of suction stroke in LP cylinder is 1.013 bar and

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