Book 2 Chapter 29: Pump Operation & Maintenance

Question 1

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

Answer 1

D) Impeller or casing or both

Question 2

Packing in the stuffing box of a centrifugal pump:
A) Should not stop leakage entirely
B) Consists of ceramic and graphite components
C) Requires no lubrication
D) Should stop leakage entirely

Answer 2

A) Should not stop leakage entirely

Question 3

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

Answer 3

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

Question 4

Priming of a centrifugal pump means:
A) Filling the casing with the fluid being pumped
B) Evacuate 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

Answer 4

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

Question 5

Wear rings are usually constructed of:
A) Ceramics or aluminum
B) Graphite or bronze
C) Bronze or cast iron
D) Steel or alloy steel

Answer 5

C) Bronze or cast iron

Question 6

Flexible couplings will compensate for:
A) Overheating of packing
B) Axial shaft misalignment
C) Shaft eccentricity due to a badly bent shaft
D) Impeller imbalance

Answer 6

B) Axial shaft misalignment

Question 7

Most pump failure and/or damage occurs:
A) After about six months of continuous service
B) Due to vapour-binding
C) During initial start-up
D) Because of inadequate operator training

Answer 7

C) During initial start-up

Question 8

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 suction head
3. Entrained air in liquid
4. Shaft misalignment
5. Wrong rotation

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

Answer 8

D) 1,2,3

Question 9

Two types of pump shaft misalignments are:
A) Axial and articulated
B) Inner and outer
C) Side and vertical
D) Axial and angular
E) Parallel and vertical

Answer 9

D) Axial and angular

Question 10

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 10

E) Is used for high pressure service

Question 11

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

Answer 11

D) 1,2,3

Question 12

A slight leakage is desired between the pump shaft and packing in the majority of pumps in order to:
A) Increase pump capacity and efficiency
B) Prevent the ingress of air
C) Prevent wearing of the wear rings
D) Prevent the pump from vapour locking
E) Lubricate the surfaces

Answer 12

E) Lubricate the surfaces

Question 13

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

Answer 13

B) Eliminate shaft wear

Question 14

Compression type packing, used in pumps, is located in the:
A) Impeller shroud
B) Diffuser housing
C) Packing chamber
D) Bearing pedestal
E) Stuffing box

Answer 14

E) Stuffing box

Question 15

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

Answer 15

E) 2,3

Question 16

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

Answer 16

D) 1,2,4

Question 17

If a centrifugal pump is located above the source of supply the suction line is equipped with a:
A) Wearing ring
B) Priming connection
C) Safety relief valve
D) Suction globe valve
E) Foot valve

Answer 17

E) Foot valve

Question 18

If a stuffing box is to prevent the ingress of air, it is equipped with a/an:
A) Seal cage
B) An anti air siphon
C) A thrust collar
D) A vacuum breaker
E) A bushing

Answer 18

A) Seal cage

Question 19

What size of packing would you use to repack a pump gland with a stuffing box bore or 8.6cm and a pump shaft diameter of 6.7cm?
A) 1.9cm
B) 1.6cm
C) 0.95cm
D) 0.5cm
E) 0.675cm

Answer 19

C) 0.95cm

Question 20

The process of filling a pump and its suction line with liquid, prior to starting the pump, is known as:
A) Wringing
B) Aligning
C) Priming
D) Distributing
E) Brinding

Answer 20

C) Priming

Question 21

Another name for lantern ring used in a pump is:
A) Stuffing box
B) Rotating seal
C) Seal cage
D) Stationary seal
E) Packing ring

Answer 21

C) Seal cage

Question 22

Mechanical seals have all the following advantages over packing except that they:
A) Are less expensive than packing
B) Do not produce wear on shafts
C) Requires less maintenance
D) Can work under very high temperatures and pressures
E) Reduce leakage to a minimum

Answer 22

A) Are less expensive than packing

Question 23

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

Answer 23

B) Speed too low

Question 24

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

Answer 24

E) Graphite

Question 25

A leaking mechanical seal may be caused by all of the following except:
A) “O” ring gaskets cut or nicked during installation
B) Seal housing bolts too tight, causing distortion of rings
C) Smooth seal faces
D) Misalignment of piping, causing distortion of pump parts
E) Excessive pump shaft vibration

Answer 25

C) Smooth seal faces

Question 26

Possible causes of a centrifugal pump stuffing box overheating may include all of the following except:
A) Excessive seal lubrication
B) Wrong grade of packing
C) Incorrect installation of packing
D) Packing too tight
E) Insufficient packing lubricant

Answer 26

A) Excessive seal lubrication

Question 27

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

Answer 27

B) Trap the air in the pump casing

Question 28

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

Answer 28

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

Question 29

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

Answer 29

A) Filling the casing and suction line with the fluid being pumped