Fluid Mechanics

711.While starting an axial flow pump, its delivery valve should be kept

1. Open
2. Closed
3. Either open or closed
4. None of these

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712.With a constant diameter impeller of a centrifugal pump

1. Its capacity varies directly as the square of speed
2. Head varies as the square of speed
3. Horsepower input varies as the square of speed
4. Head varies as the speed

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713.With decrease in particle size to be fluidised by a particular fluid, the operating range of fluidisation velocity

1. Widens
2. Squeezes
3. Does not change
4. Unpredictable from the data

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714.With diminishing cross-sectional area in case of subsonic flow in a converging nozzle, the

1. Velocity increases
2. Pressure decreases
3. Both (A) & (B)
4. Neither (A) nor (B)

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715.With increase in molecular weight of the gas, the head developed by a centrifugal compressor will

1. Decrease
2. Increase
3. Remain same
4. Unpredictable

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716.With increase in pump speed, its NPSH requirement

1. Decreases
2. Increases
3. Remains unaltered
4. Can either increase or decrease; depends on other factors

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717.With increase in temperature, the vapor pressure of liquids

1. Increases
2. Increases linearly
3. Decreases
4. Remain constant

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718.With increase in the ratio of orifice diameter to pipe diameter in case of an orificemeter, the overall pressure loss

1. Decreases
2. Increases
3. Remain constant
4. Increases linearly

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719.With increase in the ratio of orifice diameter to pipe diameter, the fraction of the orifice pressure differential that is permanently lost

1. Increases
2. Decreases
3. Remains unchanged
4. Increases exponentially

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720.With increase in the schedule number of a pipe of a particular nominal size, the

1. Wall thickness also increases
2. I.D. of the pipe decreases
3. O.D. of the pipe remains constant
4. All (A), (B) and (C)

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