Chapter 74- Pump Operation And Maintenance Flashcards
Pump wear rings are installed on an impeller by set screws, threading or:
Shrinking
Wear rings are usually constructed of:
Bronze or cast iron
Wearing rings
- Are used on impellers
- Are used on the casing
- Give protection to the shaft
- Reduce the maintenance cost of the pump
1, 2, 4
A component which is used to prevent leakage between the stationary pets of the pump and the hub of the rotating impeller
Wearing ring
This component reduces the clearances of the rotating impeller and the stationary casing
Wearing ring
When the clearances of the wearing rings increase it causes a decrease in ___________.
Efficiency
The purpose of a shaft sealing on a pump is:
To stop fluids from leaking along the shaft of the pump
The liquid to a lantern ring:
Keeps the air out of the pump
A stuffing box
- Stops air leaking into the casing when the pressure is below atmospheric
- Decreases leakage out of the casing when the pressure is a novel atmospheric.
- Is always supplied with a lantern ring
- Is filled with packing
1,4
Compressing type packing:
- Prevents air entering the pump
- Reduces the maintenance cost on pumps
- Protects the shaft from scoring and corrosion
- Is used on all mechanical seals
1, 2
The seal cage on the shaft of a centrifugal pump
Distributes sealing water to the packing
New pump packing should be installed:
Loose enough to allow leakage for lubrication
If a stuffing box is to prevent the ingress of air, it is equipped with
Seal cage
If the packing gland of a centrifugal water pump is leaking too much, you should:
Tighten up the gland but permit a slight amount of leakage
Often graphite or grease are incorporated into the packing material as a lubricant, they are also called the___________.
Saturant
Another name for compression type packing is
Jam type packing
Mechanical sealing
Are used when leakage is objectionable and replace stuffing boxes
The main advantage of a pump using a mechanical seal
Less maintenance
The component of a mechanical seal, which prevent axial leakage is the
O-ring
The main disadvantage of mechanical seals compared to packing and stuffing box methods are
Greater initial cost
Factors that may affect the type of materials used in a mechanical seals mating ring depend on
Type of fluid, temperature, pressure, pump speed, sealing design
Flexible couplings will compensate for
Axial shaft misalignment
For coupling with hubs or flanges of the same diameter a ________ can be used to check for offset or axial misalignment
Straight edge and tapered feeler gauge
A very accurate method of checking flanges for offset and axial misalignment which can be used on flanges is the
Dial indicator
