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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

Correct Answer :

C. Manometric head


Related Questions

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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

In a centrifugal pump, the regulating valve is provided on the

A. Casing

B. Delivery pipe

C. Suction pipe

D. Impeller

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4

Head developed by a centrifugal pump depends on

A. Impeller diameter

B. Speed

C. Fluid density

D. Both (A) and (B) above

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4

Kinematic similarity is said to exist between the model and the prototype, if both of them

A. Have identical velocities

B. Are equal in size and shape

C. Are identical in shape, but differ only in size

D. Have identical forces

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4

Hydraulic accumulator is used for

A. Accumulating oil

B. Supplying large quantities of oil for very short duration

C. Generally high pressures to operate hydraulic machines

D. Supplying energy when main supply fails

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4

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

The efficiency of a Pelton wheel working under constant head ________ with the increase in power.

A. Remain same

B. Increases

C. Decreases

D. None of these

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4

Puck up the wrong statement about centrifugal pump

A. Discharge a diameter

B. Head a speed²

C. Head a diameter

D. Power a speed⁴

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4

Medium specific speed of a pump implies it is

A. Centrifugal pump

B. Mixed flow pump

C. Axial flow pump

D. Any one of the above

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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

A Pelton wheel develops 1750 kW under a head of 100 metres while running at 200 r.p.m. and discharging 2500 litres of water per second. The unit discharge of wheel is

A. 0.25 m3/s

B. 0.5 m3/s

C. 1.5 m3/s

D. 2.5 m3/s

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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

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4

The specific speed of a hydraulic turbine depends upon

A. Speed and power developed

B. Discharge and power developed

C. Speed and head of water

D. Speed, power developed and head of water

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4

The centrifugal pump preferred for a specific speed between 80 to 160 r.p.m. is

A. Slow speed with radial flow at outlet

B. Medium speed with radial flow at outlet

C. High speed with radial flow at outlet

D. High speed with mixed flow at outlet

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4

The runaway speed of a hydraulic turbine is the speed

A. At full load

B. At which there will be no damage to the runner

C. Corresponding to maximum overload permissible

D. At which the turbine will run freely without load

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4

The force exerted by a jet of water (in a direction normal to flow) impinging on a fixed plate inclined at an angle θ with the jet is

A. waV/2g × sinθ

B. waV/g × sinθ

C. waV²/2g × sin2θ

D. waV²/g × sinθ

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4

A hydraulic accumulator normally consists of

A. Two cylinders, two rams and a storage device

B. A cylinder and a ram

C. Two coaxial rams and two cylinders

D. A cylinder, a piston, storage tank and control valve

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4

The specific speed of a turbine is the speed of an imaginary turbine, identical with the given turbine, which

A. Delivers unit discharge under unit head

B. Delivers unit discharge under unit speed

C. Develops unit power under unit head

D. Develops unit power under unit speed

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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

An impulse turbine is used for

A. Low head of water

B. High head of water

C. Medium head of water

D. High discharge

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4

A Pelton wheel develops 1750 kW under a head of 100 metres while running at 200 r.p.m. and discharging 2500 litres of water per second. The unit speed of the wheel is

A. 10 r.p.m.

B. 20 r.p.m.

C. 40 r.p.m.

D. 80 r.p.m.

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4

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

A. Horizontal

B. Nearly horizontal

C. Steep

D. First rise and then fall

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4

Runaway speed of a hydraulic turbine is

A. Full load speed

B. The speed at which turbine runner will be damaged

C. The speed if the turbine runner is allowed to revolve freely without load and with the wicket gates wide open

D. The speed corresponding to maximum overload permissible

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4

Mechanical efficiency of a centrifugal pump is the ratio of

A. Energy available at the impeller to the energy supplied to the pump by the prime mover

B. Actual workdone by the pump to the energy supplied to the pump by the prime mover

C. Energy supplied to the pump to the energy available at the impeller

D. Manometric head to the energy supplied by the impeller per kN of water

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4

Manometric head, in case of a centrifugal pump, is equal to

A. Suction lift + Loss of head in suction pipe due to friction + Delivery lift + Loss of head in delivery pipe due to friction + Velocity head in the delivery pipe

B. Workdone per kN of water Losses within the impeller

C. Energy per kN at outlet of impeller Energy per kN at inlet of impeller

D. All of the above

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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

Which of the following is not a reaction turbine?

A. Fourneyron turbine

B. Journal turbine

C. Thomson's turbine

D. Pelton wheel

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4

The speed ratio in case of Francis turbine varies from

A. 0.15 to 0.3

B. 0.4 to 0.5

C. 0.6 to 0.9

D. 1 to 1.5

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4

A turbine develops 10000 kW under a head of 25 metres at 135 r.p.m. Its specific speed is

A. 175.4 r.p.m.

B. 215.5 r.p.m.

C. 241.5 r.p.m.

D. 275.4 r.p.m

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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