Fluid Mechanics

Question: Erosion and pits formation on the impeller of a centrifugal pump may be due to
[A].

cavitation.

[B].

low speed of impeller.

[C].

its operation with delivery valve closed for considerable time after starting the pump.

[D].

off centering of pump with motor.

Answer: Option A

Explanation:

No answer description available for this question.

Question: For a fluid rotating at constant angular velocity about vertical axis as a rigid body, the pressure intensity varies as the
[A].

square of the radial distance.

[B].

radial distance linearly.

[C].

inverse of the radial distance.

[D].

elevation along vertical direction.

Answer: Option A

Explanation:

No answer description available for this question.

Question: If more than two branches of pipes are to be connected at the same point, then use a/an
[A].

elbow

[B].

union

[C].

tee

[D].

none of these.

Answer: Option C

Explanation:

No answer description available for this question.

Question: For pipes that must be broken at intervals for maintenance, the connector used should be a/an
[A].

union

[B].

tee

[C].

reducer

[D].

elbow

Answer: Option A

Explanation:

No answer description available for this question.

Question: A tube is specified by its
[A].

thickness only

[B].

outer diameter only

[C].

thickness & outer diameter both

[D].

inner diameter

Answer: Option C

Explanation:

No answer description available for this question.

Question: For liquid flow through a packed bed, the superficial velocity as compared to average velocity through the channel in the bed is
[A].

more

[B].

less

[C].

equal

[D].

independent of porosity

Answer: Option B

Explanation:

No answer description available for this question.

Question: Friction factor for a hydraulically smooth pipe at NRe = 2100 is f1. If the pipe is further smoothened (i.e., roughness is reduced), the friction factor at the same value of NRe, will
[A].

increase.

[B].

decrease.

[C].

remain unchanged.

[D].

increase or decrease depending on the pipe material.

Answer: Option A

Explanation:

No answer description available for this question.

Question: Maximum theoretical suction lift for water at 15°C by a centrifugal pump is 34 ft. The same for water at 90°C will be __________ ft.
[A].

40

[B].

34

[C].

8

[D].

37

Answer: Option C

Explanation:

No answer description available for this question.

Question: Choose the set of pressure intensities that are equivalent.
[A].

4.33 psi, 10 ft. of water, 8.83 inches of Hg.

[B].

4.33 psi, 10 ft. of water, 20.7 inches of Hg.

[C].

10 psi, 19.7 ft. of water, 23.3 inches of Hg.

[D].

10 psi, 19.7 ft. of water, 5.3 inches of Hg.

Answer: Option A

Explanation:

No answer description available for this question.

Question: Capacity of a rotary gear pump can be varied by
[A].

changing the speed of rotation.

[B].

bleeding air into suction.

[C].

bypassing liquid from the suction or discharge line.

[D].

all (a), (6) and (c).

Answer: Option D

Explanation:

No answer description available for this question.