Consider a centrifugal pump having a specific impeller diameter, fixed impeller speed pumping a liquid of constant density at a particular discharge capacity. With decrease in the capacity of the pump, the __________ decreases.

Which is the correct relationship for a centrifugal pump? (where, D = Impeller diameter, inches H = Head developed, ft of liquid pumped N = Speed of pump, rpm)

A

D = 1840 H^0.5/N

B

D = 1840 N/H^0.5

C

H = 1840 D^0.5/N

D

D = 1840 H/N

Discharge of a centrifugal pump is (where N = Speed of the pump impeller)

A

Directly proportional to N

B

Inversely proportional to N

C

Directly proportional to N²

D

Inversely proportional to N²

Height of liquid in agitation tank is normally maintained equal to the tank diameter. However, if the tank is too tall and a large liquid hold up is desired, then two or more impellers mounted on the same shaft may be used. The clearance between the tank bottom and the bottom most impeller should be about (where, D = impeller diameter)

A

0.5 D

B

D

C

1.5 D

D

2 D

At a constant speed of the centrifugal pump . it __________ the impeller diameter.

A

Capacity varies directly with

B

Head varies as the square of

C

Horsepower varies as the cube of

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

With a constant diameter impeller of a centrifugal pump

A

Its capacity varies directly as the square of speed

B

Head varies as the square of speed

C

Horsepower input varies as the square of speed

D

Head varies as the speed

The blades of a centrifugal impeller are said to be curved forward, if the __________ of the motion of impeller blades.

A

Inlet tip of a blade curves in a direction opposite to that

B

Outlet tip of a blade curves in a direction opposite to that

C

Inlet tip of a blade is towards the direction

D

Outlet tip of a blade is towards the direction

Specific speed of a centrifugal pump relates it with another pump having the

A

Dynamic similarity

B

Same efficiency

C

Same speed

D

Geometrical similarity

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

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

Consider a centrifugal pump having a specific impeller diameter, fixed impeller speed pumping a liquid of constant density at a particular discharge capacity. With decrease in the capacity of the pump, the __________ decreases.

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