Cavitation in a centrifugal pump can be avoided by keeping the

Cavitation in a pump creates so many undesirable effects. Out of the following, which is not an undesirable effect created by cavitation?

A

Decrease in effect

B

Increase in thrust

C

Develops noise

D

Develops high pressure

A centrifugal pump designed to pump water is employed to pump a more viscous oil. In the later case, the pump

A

Develops a lower head

B

Capacity is reduced

C

Requires more power

D

All of the above

একটি পানিপূর্ণ কুয়ার গভীরতা 20m ও ব্যাস 2 m. কুয়াটিকে পানি শূণ্য করার জন্য 5 HP এর একটি পাম্প লাগানো হল। অর্ধেক পানি তোলার পর পাম্পটি নষ্ট হয়ে গেল। বাকি পানি তোলার জন্য একই ক্ষমতা সম্পন্ন আর একটি পাম্প লাগানো হল। প্রথম পাম্প দ্বারা সম্পাদিত কাজের পরিমান নির্ণয় কর।(The depth and diameter of a water filled well are 20 m and 2 m respectively. An engine of 5 HP is attached to pump out the water. The pump was ruined after emptying half of the water. Then another pump of same capacity was attached to pump out rest of the water. Determine the work done by first pump.)

A

2.54 × 104 J

B

1.44 × 104 J

C

2.34×104 J

D

1.54 × 104 J

E

1.54 ×104 J

In centrifugal pump operation, the cavitation can be eliminated by maintaining suction pressure __________ the vapor pressure of the liquid at the suction temperature.

A

Lower than

B

Higher than

C

Equal to

D

None of these

Cavitation in a centrifugal pump results from

A

High discharge pressure

B

Low barometric pressure

C

High discharge velocity

D

High discharge rate

Cavitation occurs in a centrifugal pump when the suction pressure is

A

Less than the vapour pressure of the liquid at that temperature

B

Greater than the vapour pressure of the liquid at that temperature

C

Equal to the vapour pressure

D

Equal to the developed head

What causes cavitation in centrifugal pump?

A

High suction pressure

B

Low barometric pressure

C

Low suction pressure

D

High suction velocity

Probability of cavitation occuring becomes very high, when the local __________ resulting in water bubbles formation, which on rupture cause cavitation

A

Pressure falls below the vapour pressure

B

Pressure becomes very high

C

Temperature becomes low

D

All of the above

Working alone, pump A can empty a pool in 3 hours. Working alone, pump B can empty the same pool in 2 hours. Working together, how many minutes will it take pump A and pump B to empty the pool?

A

72

B

75

C

84

D

96

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

Cavitation in a centrifugal pump can be avoided by keeping the

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