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Q4. During your watch you observe that Main Engine LO. Sump level is rising due to contamination of lubricating oil. Describe the procedure:

a) To identify the contaminant. (6)

b) Locate the cause of contamination. (6)

c) Action to make the oil suitable for its continued usage. (4)

Q2. With reference to main refrigeration plant give reason for each of the following operational irregularities and state how these are dealt with:

a) Rapid loss of lubricating oil from the crankcase of a "vee" block compressor. (4)

b) steady "fall off" in refrigeration effect over a comparatively short period of time. (4)

c) Excessive "icing up" at compressor suction. (4)

d) Short cycling. (4)

Q3. Performance of a Fire-pump has deteriorated and is not developing required head. Describe the following:

a) The procedure for dismantling the pump. (4)

b) The likely defects and remedial measures to be taken. (3)

c) Which all Clearances are to be checked. (3)

d) Precautions during assembly. (3)

e) Checks for alignment of motor pump coupling. (3)

Q4. Describe the nature and the possible effects on machinery operation of deposits, which may adhere to the internal surfaces of exhaust gas turbo-blowers and explain how these deposits are removed. (16)

Q5. (a) A biological sewage system develops a fault, which necessitates opening the unit for repair. Explain the following:

i) The risk associated with opening the unit. (5)

ii) The precautions taken to reduce the risk. (5)

(b) Explain the significance of biological oxygen demand (B.O.D). (6)

Q6. The vessel upon which you are serving has entered dry-dock and Second engineer has asked you to inspect the shipside valves for defects. Draw a list of different ship side valves and indicate the possible defects. What maintenance is carried out on them, in the drydock? (10)

a) Explain why EACH of the defects are of importance. (6)

Q7. With reference to hydraulic deck machinery:

a) State the sources for contamination of the system. (6)

b) Describe possible effects due to contamination. (6)

c) Explain how the oil can be monitored by ships staff. (4)

Q8. Water ballast tanks of dry cargo ships and cargo tanks of oil tankers may be protected from corrosion by sacrificial anodes.

a) When do these anodes need replacement? (10)

b) i) State THREE suitable materials that can be used for anodes. (3)

ii) State any restriction on the use of these materials as anodes in oil tankers. (3)

Q9. Give reasons why each of the following conditions can result in oil being carried over with the water discharge from lubricating oil centrifuges:

a) High throughput of mixture. (6)

b) Abnormally high temperature of mixture. (6)

c) Appreciable accumulation of solids in bowl. (4)