PUMP 6012 - Pump Operations and Maintenance (Chp 29)

Question 1

If a centrifugal pump losing its prime after starting may be caused by:

1. Air leaks in the suction line or packing
2. Too low of a suction head
3. Entrained air in liquid
4. Shaft misalignment
5. Wrong rotation

A) 2, 3, 5
B) 2, 3, 4
C) 1, 2, 3
D) 1, 3
E) 1, 4, 5

Answer 1

C) 1, 2, 3

Question 2

Two types of pump shaft misalignments are:

A) Axial and articulated
B) Parallel and vertical
C) Side and vertical
D) Axial and angular
E) Inner and outer

Answer 2

D) Axial and angular

Question 3

A mechanical pump seal:

A) Is used in reciprocating pump service
B) Does not need cooling
C) Will have a substantial amount of leakage
D) Will cause more wear on the shaft than a packing seal
E) Is used for high pressure service

Answer 3

E) Is used for high pressure service

Question 4

Mechanical seals:

1. Are used where leakage is objectionable
2. Replace stuffing boxes
3. Provide a better seal than packing
4. Are less costly than stuffing boxes

A) 2, 4
B) 2, 3
C) 1, 2, 3
D) 1, 2
E) 2, 3, 4

Answer 4

C) 1, 2, 3

Question 5

A slight leakage is desired between the pump shaft and packing in the majority of pumps in order to:

A) Prevent the pump from vapour locking
B) Prevent the ingress of air
C) Increase pump capacity and efficiency
D) Lubricate the surfaces
E) Prevent wearing of the wear rings

Answer 5

D) Lubricate the surfaces

Question 6

Mechanical seals:

A) Are less expensive than packing
B) Require more maintenance than packing
C) Eliminate shaft wear
D) Can be run dry
E) Use a lantern ring

Answer 6

C) Eliminate shaft wear

Question 7

Compression type packing, used in pumps, is located in the:

A) Stuffing box
B) Bearing pedestal
C) Packing chamber
D) Diffuser housing
E) Impeller shroud

Answer 7

A) Stuffing box

Question 8

Lantern rings:

1. Prevent liquid leakage from the pump
2. Are fed by a liquid
3. Provide a seal to prevent air from entering the pump
4. Prevent leakage between the impeller and casing

A) 1, 2
B) 2, 3,4
C) 1, 2, 3
D) 2, 3
E) 3, 4

Answer 8

D) 2, 3

Question 9

A stuffing box:

1. Stops air leaking into the casing when the pressure is below atmospheric
2. Decreases casing leakage when the pressure is above atmospheric
3. Is always supplied with a lantern ring
4. Is filled with packing

A) 2, 3
B) 2, 3, 4
C) 1, 2, 4
D) 1, 4

Answer 9

C) 1, 2, 4

Question 10

If a centrifugal pump is located above the source of supply the suction line is equipped with a:

A) Suction globe valve
B) Safety relief valve
C) Priming connection
D) Foot valve
E) Wearing ring

Answer 10

D) Foot valve

Question 11

If a stuffing box is to prevent the ingress of air, it is equipped with a/an:

A) A bushing
B) A seal cage
C) A vacuum breaker
D) A thrust collar
E) An anti air siphon

Answer 11

B) A seal cage

Question 12

What size of packing would you use to repack a pump gland with a stuffing box bore of 8.6 cm and a pump shaft diameter of 6.7 cm?

A) 0.675 cm
B) 1.6 cm
C) 1.9 cm
D) 0.95 cm
E) 0.5 cm

Answer 12

D) 0.95 cm

Question 13

The process of filling a pump and its suction line with liquid, prior to starting the pump, is known as:

A)Aligning
B) Brindling
C) Distributing
D) Priming
E) Wringing

Answer 13

D) Priming

Question 14

Flexible couplings will compensate for:

A) Overheating of packing

B) Impeller imbalance

C) Bearing failure

D) Shaft eccentricity due to a badly bent shaft

E) Angular shaft misalignment

Answer 14

E) Angular shaft misalignment

Question 15

Wear rings are usually constructed of:

A) Graphite or bronze
B) Wrought iron or pig iron
C) Steel or alloy steel
D) Bronze or cast iron
E) Ceramics or aluminum

Answer 15

D) Bronze or cast iron

Question 16

Another name for a lantern ring used in a pump is:

A) Seal cage
B) Packing ring
C) Stuffing box
D) Rotating seal
E) Stationary seal

Answer 16

A) Seal cage