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Second Half Book 2 > Chapter 29 > Flashcards

Chapter 29 Flashcards

1
Q

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

A.
Lead

B.
Antimony

C.
Oil

D.
Soap

E.
Graphite

A

E.
Graphite

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2
Q

Which of the following statements about centrifugal pumps is false?
Select one:

A.
Make sure an adequate flow of cooling liquid is flowing to the seal

B.
Start the pump with the inlet valve closed

C.
Start the pump with the discharge valve closed

D.
Vent any air present from the seal housing before start up

E.
Never run the pump in a dry condition even for a few minutes

A

B.
Start the pump with the inlet valve closed

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3
Q

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

A.
Pump misalignment

B.
Balanced rotor

C.
Gas or air in liquid

D.
Insufficient suction head

E.
Worn or loose bearings

A

B.
Balanced rotor

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4
Q

To reduce leakage around the pump shaft where it passes through the casing, rings of packing, made of a _____ yet durable material, are placed in the stuffing box.
Select one:

A.
Hard, pliable

B.
Hard, ductile

C.
Soft, stiff

D.
Soft, pliable

E.
Stiff, malleable

A

D.
Soft, pliable

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5
Q

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

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

B.
Misalignment of piping, causing distortion of pump parts

C.
Smooth seal faces

D.
Excessive pump shaft vibration

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

A

C.
Smooth seal faces

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6
Q

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

A.
Volute and the diffuser

B.
Impeller and the casing

C.
Volute and the casing

D.
Impeller and the volute

E.
Diffuser and the impeller

A

B.
Impeller and the casing

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7
Q

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

A.
Moisture in oil

B.
Dirt in bearings or oil

C.
Oil level too low

D.
Poor or wrong grade of oil

E.
Sufficient cooling water

A

E.
Sufficient cooling water

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8
Q

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

A.
Low pump flows

B.
Excessive wear of the bearings

C.
Increased power consumption

D.
Shaft failure, vibrations and noise

E.
Overheating of bearings

A

A.
Low pump flows

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9
Q

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

A.
Air leaks in suction line and stuffing boxes

B.
Undersized foot valve

C.
Worn wearing rings

D.
Damaged impeller

E.
Suction head too high

A

E.
Suction head too high

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10
Q

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.
6.35 mm (1/4 in)

C.
19.05 mm (3/4 in)

D.
12.7 mm (1/2 in)

E.
9.525 mm (3/8 in)

A

A.
4.76 mm (3/16 in)

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11
Q

When the pump is located above the source of supply and a separate hand-operated priming pump is used the pump is primed in the following manner except:
Select one:

A.
The priming pump valve is shut and the main pump is primed

B.
Close the discharge valve

C.
Water issues from the priming pump discharge

D.
Close the priming valve

E.
The pump is operated exhausting air from the main pump casing and suction line

A

D.
Close the priming valve

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12
Q

Flexible couplings will compensate for:
Select one:

A.
Axial shaft misalignment

B.
Shaft eccentricity due to a badly bent shaft

C.
Overheating of packing

D.
Impeller imbalance

E.
Worn bearings

A

A.
Axial shaft misalignment

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13
Q

Possible causes of a centrifugal pump overloading the driver may include all of the following except:
Select one:

A.
Speed too low

B.
Wrong liquid, viscosity too high

C.
Wrong direction of rotation

D.
Packing too tight

E.
Discharge head too low resulting in excessive capacity

A

A.
Speed too low

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14
Q

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

A.
Bronze and cast iron

B.
Bronze and copper

C.
Bronze and steel

D.
Copper and cast iron

E.
Brass and cast iron

A

A.
Bronze and cast iron

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15
Q

Priming of a centrifugal pump means:
Select one:

A.
Evacuating the casing of air

B.
Starting the pump first

C.
Filling the casing with the fluid being pumped

D.
Installing a foot valve on the pump discharge line

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

A

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

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16
Q

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:
Select one:

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

B.
Close the discharge valve

C.
Open the external supply valve

D.
Open the air vent valve

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

A

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

17
Q

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.
4.76 mm (3/16 in)

B.
12.7 mm (1/2 in)

C.
19.05 mm (3/4 in)

D.
9.525 mm (3/8 in)

E.
6.35 mm (1/4 in)

A

D.
9.525 mm (3/8 in)

18
Q

Possible causes of a centrifugal pump stuffing box overheating may include all of the following except:
Select one:

A.
Excessive seal lubricant

B.
Insufficient packing lubricant

C.
Incorrect installation of packing

D.
Packing too tight

E.
Wrong grade of packing

A

A.
Excessive seal lubricant

19
Q

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

A.
Should not stop leakage entirely

B.
Should stop leakage entirely

C.
Consists of ceramic and graphite components

D.
Be of an extremely hard material

E.
Requires no lubrication

A

A.
Should not stop leakage entirely

20
Q

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

A.
Speed too low

B.
Impeller diameter too large

C.
Damaged impeller

D.
Worn packing

E.
Worn wearing rings

A

B.
Impeller diameter too large

21
Q

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

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

B.
Trap the air in the pump casing

C.
Open the air vent valve

D.
Open the suction valve

E.
Close the discharge valve

A

B.
Trap the air in the pump casing

22
Q

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

A.
The mating ring is fastened rigidly to the shaft

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

C.
The spring is held stationary within the pump housing

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

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

A

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

23
Q

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

A.
Stuffing box

B.
Pump casing or shaft or both

C.
Pump shaft

D.
Impeller or casing or both

E.
Seal cage

A

D.
Impeller or casing or both

24
Q

Possible causes of a centrifugal pump experiencing rapid bearing wear may include all of the following except:
Select one:

A.
Vibration

B.
Excessive thrust due to mechanical failure

C.
Lack of lubrication

D.
Wrong bearings

E.
Straight shaft

A

E.
Straight shaft

25
Q

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

A.
Suction lift too low

B.
Suction line not filled completely

C.
Inlet not completely submerged

D.
Gas or air in liquid

E.
Air leaks in suction pipe or packing glands

A

A.
Suction lift too low

26
Q

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

A.
The sealing ring is fastened to the pump shaft

B.
The spring is fastened to the pump shaft

C.
The sealing ring will turn with the shaft

D.
The mating ring is held stationary within the pump casing

E.
The mating ring will turn with the shaft

A

E.
The mating ring will turn with the shaft

27
Q

A centrifugal pump that has high suction lift and a resulting negative casing pressure will likely have:
Select one:

A.
No leakage from a lantern equipped stuffing box

B.
Wear rings installed

C.
A special shaft sleeve

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

E.
No need for a shaft sleeve

A

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

28
Q

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.)?
Select one:

A.
6.35 mm (1/4 in)

B.
12.7 mm (1/2 in)

C.
9.525 mm (3/8 in)

D.
4.76 mm (3/16 in)

E.
19.05 mm (3/4 in)

A

A.
6.35 mm (1/4 in)

29
Q

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

A.
Lack of prime

B.
Suction lift too high

C.
Speed of pump driver too low

D.
Impeller plugged

E.
Discharge head too low

A

E.
Discharge head too low

30
Q

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

A.
Do not produce wear on shafts

B.
Can work under very high temperatures and pressures

C.
Requires less maintenance

D.
Reduce leakage to a minimum

E.
Are less expensive than packing

A

E.
Are less expensive than packing

Second Half Book 2 (15 decks)

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