Book 2: 6-29 - "Pump Operation & Maintenance"

Question 1

Wear rings for a centrifugal pump can be installed on the:
Select one:

A. Stuffing box

B. Seal cage

C. Pump shaft

D. Pump casing or shaft or both

E. Impeller or casing or both

Answer 1

E. Impeller or casing or both

Question 2

Which of the following statements about stationary mechanical seals is false?
Select one:

A. As the pump shaft turns, so does the mating ring

B. The sealing ring is held stationary within the pump housing

C. The spring is held stationary within the pump housing

D. As the pump shaft turns, so does the sealing ring

E. The mating ring is fastened rigidly to the shaft

Answer 2

D. As the pump shaft turns, so does the sealing ring

Question 3

Possible causes of a centrifugal pump discharge pressure being too low may include all of the following except:
Select one:

A. Impeller diameter too large

B. Speed too low

C. Damaged impeller

D. Worn packing

E. Worn wearing rings

Answer 3

A. Impeller diameter too large

Question 4

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.)?
Select one:

A. 6.35 mm (1/4 in)

B. 12.7 mm (1/2 in)

C. 19.05 mm (3/4 in)

D. 9.525 mm (3/8 in)

E. 4.76 mm (3/16 in)

Answer 4

D. 9.525 mm (3/8 in)

Question 5

Possible causes of a centrifugal pump loosing prime after starting may include all of the following except:
Select one:

A. Inlet not completely submerged

B. Gas or air in liquid

C. Suction line not filled completely

D. Suction lift too low

E. Air leaks in suction pipe or packing glands

Answer 5

D. Suction lift too low

Question 6

Possible causes of a centrifugal pump experiencing excessive vibration may include all of the following except:
Select one:

A. Insufficient suction head

B. Pump misalignment

C. Balanced rotor

D. Worn or loose bearings

E. Gas or air in liquid

Answer 6

C. Balanced rotor

Question 7

Possible causes of a centrifugal pump not delivering any liquid may include all of the following except:
Select one:

A. Discharge head too low

B. Impeller plugged

C. Speed of pump driver too low

D. Lack of prime

E. Suction lift too high

Answer 7

A. Discharge head too low

Question 8

Wear rings are found in dynamic centrifugal pumps between the:
Select one:

A. Impeller and the casing

B. Impeller and the volute

C. Volute and the casing

D. Diffuser and the impeller

E. Volute and the diffuser

Answer 8

A. Impeller and the casing

Question 9

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.)?
Select one:

A. 4.76 mm (3/16 in)

B. 19.05 mm (3/4 in)

C. 6.35 mm (1/4 in)

D. 12.7 mm (1/2 in)

E. 9.525 mm (3/8 in)

Answer 9

A. 4.76 mm (3/16 in)

Question 10

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:
Select one:

A. Open the priming valve

B. Open the air vent valve

C. Open the discharge valve

D. When water flows from the vents the pump is primed

E. Water flows into the pump and suction line where it is prevented from escaping by the foot valve

Answer 10

C. Open the discharge valve

Question 11

Misalignment of shafts connected by rigid couplings does NOT cause:
Select one:

A. Increased power consumption

B. Excessive wear of the bearings

C. Overheating of bearings

D. Low pump flows

E. Shaft failure, vibrations and noise

Answer 11

D. Low pump flows

Question 12

Priming of a centrifugal pump means:
Select one:

A. Installing a foot valve on the pump discharge line

B. Evacuating the casing of air

C. Filling the casing with the fluid being pumped

D. Starting the pump first

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

Answer 12

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

Question 13

The usual materials favored for wear rings are _____ which tend to wear in a smooth manner.
Select one:

A. Bronze and copper

B. Copper and cast iron

C. Brass and cast iron

D. Bronze and steel

E. Bronze and cast iron

Answer 13

E. Bronze and cast iron

Question 14

In the case where the pump is below the source of supply the pump is primed in the following manner except:
Select one:

A. Open the suction valve

B. Open the air vent valve

C. Trap the air in the pump casing

D. When water flows from the vents the pump is primed

E. Close the discharge valve

Answer 14

C. Trap the air in the pump casing

Question 15

A leaking mechanical seal may be caused by all of the following except:
Select one:

A. Smooth seal faces

B. Misalignment of piping, causing distortion of pump parts

C. Seal housing bolts too tight, causing distortion of rings

D. Excessive pump shaft vibration

E. “O” ring gaskets cut or nicked during installation

Answer 15

A. Smooth seal faces

Question 16

Packing in the stuffing box of a centrifugal pump:
Select one:

A. Consists of ceramic and graphite components

B. Should stop leakage entirely

C. Be of an extremely hard material

D. Requires no lubrication

E. Should not stop leakage entirely

Answer 16

E. Should not stop leakage entirely

Question 17

Possible causes of a centrifugal pump experiencing overheated bearings may include all of the following except:
Select one:

A. Sufficient cooling water

B. Moisture in oil

C. Oil level too low

D. Dirt in bearings or oil

E. Poor or wrong grade of oil

Answer 17

A. Sufficient cooling water

Question 18

Frequently, a lubricating material such as _____, called the saturant, is incorporated into the packing material.
Select one:

A. Soap

B. Graphite

C. Oil

D. Lead

E. Antimony

Answer 18

B. Graphite

Question 19

Mechanical seals have all the following advantages over packing except that they:
Select one:

A. Requires less maintenance

B. Do not produce wear on shafts

C. Can work under very high temperatures and pressures

D. Reduce leakage to a minimum

E. Are less expensive than packing

Answer 19

E. Are less expensive than packing

Question 20

Flexible couplings will compensate for:
Select one:

A. Overheating of packing

B. Shaft eccentricity due to a badly bent shaft

C. Worn bearings

D. Axial shaft misalignment

E. Impeller imbalance

Answer 20

D. Axial shaft misalignment