MEO Oral Exam Questions on Pumps – Marine Engineering
What is cavitation, causes and remedies ?
- Cavitation can be occurred when the pump suction contains air or when the pump is running faster than the designed speed.
- Low pressure regions occur in the flow at points where high local velocities exist.
- If vaporisation occurs due to these low pressure areas then bubbles occur, these expand as they move with the flow and collapse when they reach a high pressure region.
- Such formation and collapse of bubbles is very rapid and collapse near a surface can generate very high pressure hammer blows which results in pitting, noise, vibration, and fall off in the pump efficiency.
- So the pump should be run at designed speed and throttling of the suction valve should be avoided.
What are the reasons for ballast pump not delivering water ?
- Incomplete priming
- Too high suction lift
- Low net positive suction head
- Air leaks in suction line
- Gas or air lock
- Suction filter choke
Screw pump overhaul procedure ?
- Put off breaker and remove fuse from motor starter box
- Close suction and discharge valve
- Remove suction and discharge pipe flange bolt & nut, coupling bolt of motor coupling
- Remove pump foundation bolts & take out pump from motor
- Remove cover both side & remove driver screw & driven screw with bearing and mechanical seal
- Inspect mechanical seal, bearing and renew if required.
- Clean all parts and assemble back.
What are the check points in screw pumps ?
- Mechanical seal
- Bearing
- Driver screw and driven screw wear & tear
- Pump casing internal surface wear
- Clearance between driver and driven screw
- Clearance between driven and casing.
- Clearance between driver and casing.
What is the centrifugal pump overhaul procedure ?
- Put off breaker and remove fuse from motor starter box
- Close suction and discharge valve
- Remove suction and discharge pipe flange bolt & nut, coupling bolt of motor coupling
- Remove pump foundation bolts & take out pump from motor
- Remove impeller lock & nut & take out the impeller
- Remove mechanical seal.
- Remove bearing cover from other side & take out shaft with ball bearing
- Renew mechanical seal and bearings if required.
- Clean and inspect all parts and assemble.
What are the check points in centrifugal pumps ?
- Impeller
- Wear ring
- Neck bush
- Ball bearing
- Shaft.
- Mechanical seal.
Reference:
Oral Guide by – MIN ZAR TAR
One thought on “MEO Oral Exam Questions on Pumps – Marine Engineering”
I like to read those topic.thanks for co operation.
plz add more question about pump.