Marine Engineering Study Materials

Trouble

Cause

Remedy

1. Tank empty
2. Foam instead of liquid in tank
3. Valves are shut
4. Incorrect rotation of motor
5. Blockage or leakage in piping system.

1. If the tank is empty, fill to at least to the low level switch. Check the condition of the pump according to the manufacturer´s instruction.
2. If the pump is pumping foam instead of liquid, this will be evident due to severe vibration. Add water to the tank and try
   again. If adding water does not help, reduce the level of foam by pouring antifoam agent into the tank (1 cup per 2 cubic metres of foam and sewage).
3. Check that shut-off valves are fully open and not clogged.
4. If the direction of rotation of the pump is wrong, change wiring accordingly.
5. Close the valves that isolate the collecting unit from the piping system and start the pump again. If vacuum now builds up, there
   must be a leak in the piping system.

1. Make sure that pump is stopped and shutoff valve is closed.
2. Remove plug and clean out ejector. If this procedure is unsuccesful, the following
   steps should be taken.
3. Dismantle flange connections and remove bend.
4. Dismantle flange connections and remove ejector from tank.
5. Dismantle flange connections and remove connection cone.
6. Withdraw non-return valve from ejector.
7. Clean sealing surfaces and if necessary replace rubber flap.
8. While the ejector is dismantled, it is advisable to check the nozzle and the inside of the ejector housing for sludge and impurities.
9. Refit ejector and non-return valve in reverse order to dismantling, at same time checking the condition of all seals and replacing as
   necessary.
10. Make sure that non-return valve is correctly positioned.

1. Motor defect
2. No power
3. Automatic fuses off
4. Impeller defect
5. Failure in float switch.

1. Replace motor.
2. Check the electrical system.
3. Check reason for this before
   switching fuses on.
4. Measure clearance of impeller.
5. Check float switch and wiring, repair or replace.

1. Failure in float switch.
2. Too much water enters the plant.

1. Check float switch and wiring, repair or replace.
2. Allowed in peak periods. Try to
   reduce peak flow.

1. Wrong rotation direction.
2. Impeller defect.
3. Valve in discharge system closed
   or defect.

1. Change phases on electrical motor.
2. Replace impeller.
3. Check valves in discharge system.

1. Pump is clogged.
2. Discharge pump defect.
3. Too much water enters the plant.

1. Open and clean pump.
2. Open bypass and repair/replace
   discharge pump.
3. Allowed in peak periods. Try to
   reduce peak flow.

1. Defect non-return valve.
2. Wrong direction of rotation.

1. Repair or replace.
2. Change phases on electrical motor.

1. Hose or pipe defect.
2. Air distributors clogged or defect.

1. Repair or replace.
2. Clean or replace air distributors.

1. Too much mineral sludge.
2. Bacterias killed. Brown sludge
   indicates normal bacteria life. Black sludge indicates that bacterias are killed.

1. Check sludge content and discharge if required.
2. Check air blower function by opening the man holes. Surface bubbles must be seen during blower operation.

1. Too much water enters the plant,
   thereby creating too high hydraulic loading.
2. From newly started plants, bacterias not yet formed.
3. Bacterias killed.

1. Allowed in peak periods. Try to
   reduce peak flow.
2. Check start up date. Time required
   for bacteria formation is approximately 4 (four) weeks.
3. See “plant smells”.

1. Insufficient operation of sludge
   return pump.

1. Check and adjust return sludge air
   valve. Check air hoses.

1. Dosing pump is not operating.
2. Disinfectant tank is empty.
3. Dosage rate is too low.
4. Disinfection chlorine is obsolete.

1. Check pump operation.
2. Fill it up with approved disinfectant.
3. Increase dosage by adjusting dosing pump.
4. Replace with “fresh” chlorine.