MARINE PUMPS

Check the following in order to tackle issues

Delivery Failure – if the pump is not able to deliver at the required pressure.

• Ensure that the pump is primed properly
• Check if the pump is moving with sufficient speed
• Check for air leakage
• Ensure that the impeller/gear/screw or other liquid driving mechanism is not broken or damaged
• The pump shaft should move in the right direction
• Check that the suction lift is not more than required

Priming Failure

Priming is required in order to start most of the pumps. If the pump is not able to prime properly, check the following:

• Leakage in pump joint
• Leakage in gland joint
• Air leakage
• Faulty priming drive

Inability to Build Pressure

• If the priming is done properly
• The air cocks are not open
• Internal moving parts (impeller/ screw etc.) are not damaged
• Wear Rings are not worn out or damaged
• The pump is running at the right speed
• There are no other mechanical defects in the pump
• Check for cavitation in the casing of the pump

Excessive Vibration:

• Ensure there is no loose foundation
• The alignment of the pump is proper
• There is no impeller imbalance or erosion
• There are no mechanical faults
• The distance piece between the pump shaft and motor shaft is of correct length and, is not worn out
• The rubber bush piece connecting the motor and pump shaft is not worn out
• There are no worn bearings or bent shafts

Reduced Capacity:

• The pump is running at proper speed
• There is no air leakage
• There is no obstruction in the suction pipe
• Ensure that the suction lift and temperature are not too high
• The total dynamic head is not larger than the rated
• The setting of the pump relief valve is not below the required value

Motor Overload

This is a very common pump-driver problem found on board ships. If the pump motor overloads, then immediately check:

• The Speed of the pump is not high
• The quantity of liquid pumped is not too much
• The viscosity of the liquid is up to the mark
• Valves in the line are in closed position
• Problem or obstruction in the rotary parts of the pump

Loss of liquid

If the pump loses liquid, after starting or during running:

• Check if the suction lift is as required
• Check for any kind of leakage in the suction line
• Check the temperature of the liquid
• Ensure the relief valve of the pump is set at right value to avoid loss of liquid to overflow line