Book 2 Chapter 29: Pump Operation & Maintenance Flashcards
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
D) Impeller or casing or both
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
A) Should not stop leakage entirely
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
B) A lantern ring or seal cage in the stuffing box
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
C) Filling the casing and suction line with the fluid being pumped
Wear rings are usually constructed of:
A) Ceramics or aluminum
B) Graphite or bronze
C) Bronze or cast iron
D) Steel or alloy steel
C) Bronze or cast iron
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
B) Axial shaft misalignment
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
C) During initial start-up
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
D) 1,2,3
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
D) Axial and angular
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
E) Is used for high pressure service
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
D) 1,2,3
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
E) Lubricate the surfaces
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
B) Eliminate shaft wear
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
E) Stuffing box
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
E) 2,3
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
D) 1,2,4
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
E) Foot valve
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
A) Seal cage
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
C) 0.95cm
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
C) Priming
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
C) Seal cage
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
A) Are less expensive than packing
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
B) Speed too low
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
E) Graphite
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
C) Smooth seal faces
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
A) Excessive seal lubrication
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
B) Trap the air in the pump casing
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
B) A lantern ring or seal cage in the stuffing box
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
A) Filling the casing and suction line with the fluid being pumped
