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4

Casting of a centrifugal pump is designed so as to minimize

A. Friction loss

B. Cavitations

C. Static head

D. Loss of kinetic energy

Correct Answer :

D. Loss of kinetic energy


Related Questions

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4

Francis, Kaplan and propeller turbines fall under the category of

A. Impulse turbines

B. Reaction turbines

C. Axial flow turbines

D. Mixed flow turbines

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4

The maximum hydraulic efficiency of an impulse turbine is (where φ = Angle of blade tip at outlet)

A. (1 + cos φ)/2

B. (1 - cos φ)/2

C. (1 + sin φ)/2

D. (1 - sin φ)/2

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4

A double overhung Pelton wheel has

A. Two jets

B. Two runners

C. Four jets

D. Four runners

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4

Which of the following pump is successfully used for lifting water from deep wells?

A. Centrifugal pump

B. Reciprocating pump

C. Jet pump

D. Air lift pump

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4

Which of the following is not an impulse turbine?

A. Girad turbine

B. Turgo turbine

C. Pelton wheel

D. Kaplan turbine

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4

In a centrifugal pump casing, the flow of water leaving the

A. Radial

B. Axial

C. Centrifugal

D. Vortex

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4

A Pelton wheel is

A. Tangential flow impulse turbine

B. Inward flow impulse turbine

C. Outward flow impulse turbine

D. Inward flow reaction turbine

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4

According to fan laws, for fans having constant wheel diameter, the air or gas capacity varies

A. Directly as fan speed

B. Square of fan speed

C. Cube of fan speed

D. Square root of fan speed

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4

In an outward flow reaction turbine

A. The water flows parallel to the axis of the wheel

B. The water enters at the centre of the wheel and then flows towards the outer periphery of the wheel

C. The water enters the wheel at the outer periphery and then flows towards the centre of the wheel

D. The flow of water is partly radial and partly axial

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4

According to fan laws, at constant pressure, the speed capacity and power vary

A. Directly as the air or gas density

B. Inversely as square root of density

C. Inversely as density

D. As square of density

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4

Saving of work done and power by fitting an air vessel to double acting reciprocating pump is of the order of

A. 39.2 %

B. 49.2 %

C. 68.8 %

D. 84.8 %

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4

A Pelton wheel working under a constant head and discharge, has maximum efficiency when the speed ratio is

A. 0.26

B. 0.36

C. 0.46

D. 0.56

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4

If the ratio's of the corresponding forces acting at corresponding points are equal, then the model and the prototype are said to have.

A. Geometric similarity

B. Kinematic similarity

C. Dynamic similarity

D. None of these

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4

For starting an axial flow pump, its delivery valve should be

A. Closed

B. Open

C. Depends on starting condition and flow desired

D. Could be either open or closed

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4

When a piping system is made up primarily of vertical lift and very little pipe friction, the pump characteristics should be

A. Horizontal

B. Nearly horizontal

C. Steep

D. First rise and then fall

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4

In a Francis turbine runner, the numbers of blades are generally between

A. 2 to 4

B. 4 to 8

C. 8 to 16

D. 16 to 24

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4

A centrifugal pump will start delivering liquid only when the pressure rise in the impeller is equal to the

A. Kinetic head

B. Velocity head

C. Manometric head

D. Static head

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4

Which of the following pump is successfully used for lifting water to the turbines?

A. Centrifugal pump

B. Reciprocating pump

C. Jet pump

D. Air lift pump

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4

The speed of a turbine runner is

A. Directly proportional to H1/2

B. Inversely proportional to H1/2

C. Directly proportional to H3/2

D. Inversely proportional to H3/2

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4

The unit speed of the turbine runner is

A. N/√H

B. N/H

C. N/H3/2

D. N/H²

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4

The mechanical efficiency of an impulse turbine is

A. Ratio of the actual power produced by the turbine to the energy actually supplied by the turbine

B. Ratio of the actual work available at the turbine to the energy imparted to the wheel

C. Ratio of the Work done on the wheel to the energy of the jet

D. None of the above

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4

The ratio of actual work available at the turbine to the energy imparted to the wheel is known as ________ efficiency.

A. Hydraulic

B. Mechanical

C. Overall

D. None of these

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4

According to fan laws, at constant weight of air or gas, the speed, capacity and pressure vary

A. Directly as the air or gas density

B. Inversely as square root of density

C. Inversely as density

D. As square of density

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4

Power required (in watts) to drive a centrifugal pump is (where Hm = Manometric head in metres, w = Specific weight in N/m3, Q = Discharge of the pump in m3/s, and ηo = Overall efficiency of the pump)

A. (w Hm) / (Q × ηo)

B. (w Hm Q) / ηo

C. (w Q) / (Hm × ηo)

D. (w Q ηo) / Hm

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4

The cavitation in reaction turbines is avoided, to a great extent by

A. Installing the turbine below the tail race level

B. Using stainless steel runner of the turbine

C. Providing highly polished blades to the runner

D. All of the above

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4

Slip of a reciprocating pump is defined as the

A. Ratio of actual discharge to the theoretical discharge

B. Sum of actual discharge and the theoretical discharge

C. Difference of theoretical discharge and the actual discharge

D. Product of theoretical discharge and the actual discharge

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4

Multistage centrifugal pumps are used to obtain

A. High discharge

B. High head

C. Pumping of viscous fluids

D. High head and high discharge

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4

Which of the following turbine is preferred for a specific speed of 60 to 300 r.p.m.?

A. Pelton wheel

B. Francis turbine

C. Kaplan turbine

D. None of these

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4

Specific speed for reaction turbines ranges from

A. 0 to 4.5

B. 10 to 100

C. 80 to 200

D. 250 to 300

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4

If the net positive suction head (NPSH) requirement for the pump is not satisfied, then

A. No flow will take place

B. Cavitation will be formed

C. Efficiency will be low

D. Excessive power will be consumed