Multistage Centrigal Pumps Flashcards
What is the function of a bearing isolator in a Flowserve multistage pump?
A bearing isolator prevents oil leakage from the bearing housing while keeping contaminants like dust, water, and debris from entering. It helps extend bearing life by maintaining proper lubrication conditions.
What is the function of the thrust ball bearings in this pump?
Thrust ball bearings handle axial loads generated by the pump’s impellers, preventing excessive axial movement and ensuring smooth shaft rotation.
What is the function of the sleeve bearings in this pump?
Sleeve bearings support radial loads and provide a low-friction surface for the shaft to rotate. They rely on an oil film for lubrication rather than rolling elements.
What types of bearings are commonly used in a Flowserve multistage pump?
Thrust ball bearings (handles axial loads).
Sleeve bearings (handles radial loads).
What are the main differences between axial and radial loads?
Axial Load – Force acts parallel to the shaft.
Radial Load – Force acts perpendicular to the shaft.
How does a thrust ball bearing handle axial and radial loads?
It only handles axial loads. It is not designed for radial loads and will fail if subjected to them.
How does a sleeve bearing handle axial and radial loads?
A sleeve bearing primarily handles radial loads. It has limited axial load capacity and typically requires an external thrust bearing to handle axial forces.
What are the key steps to inspect a thrust ball bearing for wear?
Check for discoloration (overheating).
Look for pitting, scoring, or brinelling on the raceways.
Spin the bearing by hand – roughness indicates wear.
Measure axial play with a dial indicator.
How do you inspect a sleeve bearing for wear?
Check for scoring, scratching, or wiping on the bearing surface.
Measure bearing clearance using a feeler gauge or dial indicator.
Ensure proper oil film formation – a dry surface indicates lubrication failure.
If a bearing were like a car tire, what part of the load would be axial, and what would be radial?
The weight of the car pressing down on the tire = Radial Load.
The force when the car moves forward or backward = Axial Load.
If a bearing were like a spinning pizza cutter, what would be axial and radial loads?
Pressing down on the cutter = Radial Load.
Pushing it forward to slice = Axial Load.
How does high discharge pressure affect axial load on the pump?
Higher discharge pressure increases axial thrust, which overloads the thrust bearings if not properly balanced.
What safety precautions should be taken before starting a bearing repair?
Lockout/tagout the pump system.
Wear proper PPE (gloves, safety glasses, etc.).
Ensure zero pressure in the system before disassembly.
What tools are used to remove and install a thrust ball bearing?
Bearing puller or hydraulic press for removal.
Dial indicator for alignment checks.
What happens if a thrust bearing is over-tightened during installation?
Increases friction and heat buildup.
Can cause premature failure or bearing seizure.
What happens if sleeve bearing clearance is too tight or too loose?
Too tight: Oil film won’t form, leading to overheating.
Too loose: Shaft instability and excessive vibration.
What are critical post-repair checks before starting the pump?
Verify lubrication levels and ensure proper oil flow.
Check axial and radial clearances.
Rotate the shaft manually to confirm smooth operation.
What symptoms indicate improper bearing installation after startup?
Excessive vibration in axial/radial directions.
Unusual noise (grinding, knocking).
Oil leaks or bearing overheating.
What are common failure modes of a bearing isolator?
Wear and tear of the grooves.
Misalignment during installation.
Oil contamination or breakdown.
What should you check before replacing a bearing isolator?
Confirm the leak is from the isolator and not from another issue.
Measure shaft axial/radial play.
Ensure proper lubrication return flow.
How do you properly install a new bearing isolator?
Clean the mounting surface before installation.
Align and press-fit the isolator carefully.
Ensure shaft rotation is smooth post-installation.
What should you do if a new bearing isolator is still leaking oil?
Verify proper installation and seating.
Check for excessive shaft movement.
Ensure oil is not overfilled in the system.
Why is axial shaft movement important when assessing a bearing isolator?
Excessive movement can compromise the seal, leading to oil leakage and early failure.
What are the benefits of upgrading to a labyrinth bearing isolator?
Longer lifespan (no physical contact wear).
Better contamination protection (keeps dirt and moisture out).
Reduced friction and energy efficiency improvement.
