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4

Centrifugal pump is started with its delivery valve

A. Kept fully closed

B. Kept fully open

C. Irrespective of any position

D. Kept 50% open

Correct Answer :

A. Kept fully closed


Related Questions

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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

Slip of a reciprocating pump is negative, when

A. Suction pipe is short and pump is running at low speeds

B. Delivery pipe is long and pump is running at high speeds

C. Suction pipe is short and delivery pipe is long and the pump is running at low speeds

D. Suction pipe is long and delivery pipe is short and the pump is running at high speeds

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4

A ship with jet propulsion draws water through inlet orifices at right angles to the direction of its motion. The propelling force of the jet is (where a = Area of the jet, Vr = Relative velocity of the jet and ship = V + v, v = Velocity of the ship, and V = Velocity of the jet issuing from the ship)

A. waVr /g × (Vr + v)

B. waVr /g × (Vr - v)

C. waVr /g × (Vr + v)²

D. waVr /g × (Vr - v)²

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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

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

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 force exerted (in Newton) by a jet of water impinging normally on a fixed plate is (where w = Specific weight of water in N/m3, a = Crosssectional area of jet in m², and V = Velocity of jet in m/s)

A. waV / 2g

B. waV / g

C. waV² / 2g

D. waV² / g

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4

The overall efficiency of a reaction turbine is the ratio of

A. Power produced by the turbine to the energy actually supplied by the turbine

B. Actual work available at the turbine to the energy imparted to the wheel

C. Workdone on the wheel to the energy (or head of water) actually supplied to the turbine

D. None of the above

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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

A turbine pump is basically a centrifugal pump equipped additionally with

A. Adjustable blades

B. Backward curved blades

C. Vaned diffusion casing

D. Inlet guide blades

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4

Power required to drive a centrifugal pump is directly proportional to ________ of its impeller.

A. Diameter

B. Square of diameter

C. Cube of diameter

D. Fourth power of diameter

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4

In a centrifugal pump, the liquid enters the pump

A. At the top

B. At the bottom

C. At the canter

D. From sides

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4

Francis turbine is best suited for

A. Medium head application from 24 to 180 m

B. Low head installation up to 30 m

C. High head installation above 180 m

D. All types of heads

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4

Reaction turbines are used for

A. Low head

B. High head

C. High head and low discharge

D. Low head and high discharge

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4

Maximum impulse will be developed in hydraulic ram when

A. Waste valve closes suddenly

B. Supply pipe is long

C. Supply pipe is short

D. Ram chamber is large

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4

The speed of an imaginary turbine, identical with the given turbine, which will develop a unit power under a unit head, is known as

A. Normal speed

B. Unit speed

C. Specific speed

D. None of these

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4

The power developed by a turbine is (where H = Head of water under which the turbine is working)

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 angle of taper on draft tube is

A. Greater than 15°

B. Greater than 8°

C. Greater than 5°

D. Less than 8°

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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

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

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 width of the bucket for a Pelton wheel is generally ________ the diameter of jet.

A. Double

B. Three times

C. Four times

D. Five times

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4

The discharge through a turbine 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

For 450 m head of water, _________ shall be used.

A. Pelton wheel

B. Kaplan turbine

C. Francis turbine

D. None of these

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4

The cavitation in a hydraulic machine

A. Causes noise and vibration of various parts

B. Reduces the discharge of a turbine

C. Causes sudden drop in power output and efficiency

D. All of the above

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4

For centrifugal pump impeller, the maximum value of the vane exit angle is

A. 10° to 15°

B. 15° to 20°

C. 20° to 25°

D. 25° to 30°

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4

Multistage centrifugal pumps are used to

A. Give high discharge

B. Produce high heads

C. Pump viscous fluids

D. All 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

A double overhung Pelton wheel has

A. Two jets

B. Two runners

C. Four jets

D. Four runners

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4

In a reaction turbine, the draft tube is used

A. To run the turbine full

B. To prevent air to enter the turbine

C. To increase the head of water by an amount equal to the height of the runner outlet above the tail race

D. To transport water to downstream