Chapter 29 Pump Operation & Maintenance

Question 1

1.	What size packing should be used if the stuffing box bore on a pump is 63.5 mm (2.5 in.) and the shaft diameter is 50.8 mm (2 in.)?
A.	12.7 mm (1/2 in)
B.	19.05 mm (3/4 in)
C.	9.525 mm (3/8 in)
D.	6.35 mm (1/4 in)
E.	4.76 mm (3/16 in)

Answer 1

D. 6.35 mm (1/4 in)

Question 2

2.	What size packing should be used if the stuffing box bore on a pump is 76.2 mm (3 in.) and the shaft diameter is 57.2 mm (2.25 in.)?
A.	19.05 mm (3/4 in)
B.	12.7 mm (1/2 in)
C.	9.525 mm (3/8 in)
D.	6.35 mm (1/4 in)
E.	4.76 mm (3/16 in)

Answer 2

C. 9.525 mm (3/8 in)

Question 3

3.	What size packing should be used if the stuffing box bore on a pump is 50.8 mm (2 in.) and the shaft diameter is 41.275 mm (1.625 in.)? 
A.	19.05 mm (3/4 in)
B.	12.7 mm (1/2 in)
C.	9.525 mm (3/8 in)
D.	6.35 mm (1/4 in)
E.	4.76 mm (3/16 in)

Answer 3

E. 4.76 mm (3/16 in)

Question 4

4.	The usual materials favored for wear rings are \_\_\_\_\_ which tend to wear in a smooth manner. 
A.	Brass and cast iron
B.	Bronze and steel
C.	Bronze and cast iron
D.	Copper and cast iron
E.	Bronze and copper

Answer 4

C. Bronze and cast iron

Question 5

5.	Wear rings for a centrifugal pump can be installed on the:
A.	Pump shaft
B.	Impeller or casing or both
C.	Pump casing or shaft or both
D.	Stuffing box
E.	Seal cage

Answer 5

B. Impeller or casing or both

Question 6

6. Flexible couplings will compensate for:

A.	Axial shaft misalignment
B.	Overheating of packing
C.	Shaft eccentricity due to a badly bent shaft
D.	Impeller imbalance
E.	Worn bearings

Answer 6

A. Axial shaft misalignment

Question 7

7.	Misalignment of shafts connected by rigid couplings does NOT cause: 
A.	Overheating of bearings
B.	Low pump flows
C.	Excessive wear of the bearings
D.	Increased power consumption
E.	Shaft failure, vibrations and noise

Answer 7

B. Low pump flows

Question 8

8.	Wear rings are found in dynamic centrifugal pumps between the: 
A.	Impeller and the casing
B.	Impeller and the volute
C.	Volute and the diffuser
D.	Diffuser and the impeller
E.	Volute and the casing

Answer 8

A. Impeller and the casing

Question 9

9.	Possible causes of a centrifugal pump experiencing excessive vibration may include all of the following except: 
A.	Gas or air in liquid
B.	Insufficient suction head
C.	Pump misalignment
D.	Balanced rotor
E.	Worn or loose bearing

Answer 9

D. Balanced rotor

Question 10

10. When the pump is located above the source of supply and the priming water comes from an external source the pump is primed in the following manner except:
    A. Close the discharge valve
    B. Open the external supply valve
    C. Open the air vent valve
    D. Water flows into the pump and suction line where it is prevented from escaping by the foot valve
    E. When air flows from the vent valves the pump is primed

Answer 10

E. When air flows from the vent valves the pump is primed

Question 11

11. When the pump is located above the source of supply and the priming water is supplied from the pump discharge line the pump is primed in the following manner except:
    A. Open the discharge valve
    B. Open the priming valve
    C. Open the air vent valve
    D. Water flows into the pump and suction line where it is prevented from escaping by the foot valve
    E. When water flows from the vents the pump is primed

Answer 11

A. Open the discharge valve

Question 12

12. Possible causes of a centrifugal pump overloading the driver may include all of the following except:
    A. Discharge head too low resulting in excessive capacity
    B. Speed too low
    C. Wrong liquid, viscosity too high
    D. Wrong direction of rotation
    E. Packing too tight

Answer 12

B. Speed too low

Question 13

13. A centrifugal pump that has high suction lift and a resulting negative casing pressure will likely have:
    A. Wear rings installed
    B. A lantern ring or seal cage in the stuffing box
    C. No leakage from a lantern equipped stuffing box
    D. No need for a shaft sleeve
    E. A special shaft sleeve

Answer 13

B. A lantern ring or seal cage in the stuffing box

Question 14

14. Priming of a centrifugal pump means:
    A. Filling the casing with the fluid being pumped
    B. Evacuating the casing of air
    C. Filling the casing and suction line with the fluid being pumped
    D. Installing a foot valve on the pump discharge line
    E. Starting the pump first

Answer 14

C. Filling the casing and suction line with the fluid being pumped

Question 15

15.	Frequently, a lubricating material such as \_\_\_\_\_, called the saturant, is incorporated into the packing material. 
A.	Oil
B.	Soap
C.	Lead
D.	Antimony
E.	Graphite

Answer 15

E. Graphite

Question 16

16. Possible causes of a centrifugal pump experiencing rapid bearing wear may include all of the following except:
    A. Straight shaft
    B. Vibration
    C. Excessive thrust due to mechanical failure
    D. Lack of lubrication
    E. Wrong bearings

Answer 16

A. Straight shaft

Question 17

17. Which of the following statements about centrifugal pumps is false?
    A. Never run the pump in a dry condition even for a few minutes
    B. Vent any air present from the seal housing before start up
    C. Make sure an adequate flow of cooling liquid is flowing to the seal
    D. Start the pump with the inlet valve closed
    E. Start the pump with the discharge valve close

Answer 17

D. Start the pump with the inlet valve closed