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Q4. (a) Describe the safe isolation procedure of centrifuges on board ships before starting maintenance work. (6)

(b) Describe maintenance schedule of centrifuges with brief description of the procedure for satisfactory operation. (10)

Q8. Explain how each of the following conditions contributes to the satisfactory performance of oil centrifuges. A. Correct bowl speed; B. Cleanliness of bowl; C. Low rate of feed to the bowl; D. Contaminated oil preheated prior to centrifuging; E. Contaminated oil allowed standing for an appreciable time prior to centrifuging.

Q9: A heavy Oil purifier vibrates badly when just shutting down and coming to a stop. Suggest some reasons for this vibration problem, when you have already made an inspection of its drive mechanism and casing and found nothing unusual.

Q2. i) Sketch and describe the modern purification system using ‘ALCAP’ concept for purifying fuel specific gravity about 0.991. (8)

ii) Explain how ‘ALCAP’ separator operates as clarifier & how is the water drained off? (4)

iii) What is ‘paring disc’? How does it function? (4)

Q5. Explain how each of the following, conditions contribute to the satisfactory

performance of oil centrifuges (16)

(a) correct bowl speed

(b) cleanliness of bowl

(c) low rate of feed to bowl

(d) Contaminated oil allowed to stand for an appreciable time prior to centrifuging.

Q7. i) What is the significance of oil water interface in fuel oil purifiers? (3)

ii) Explain the principle of 'desludging operation'. (6)

iii) What is the purposed of 'operating water', 'sealing water' and 'replacement water'', How is operating water supplied and at what pressure? (7)

Q6. i) Sketch and describe the 'drive mechanism' of a centrifuge? (10)

ii) State the component in the horizontal and vertical drives (3)

iii) state the purpose of providing: (3)

a) clutch mechanism

b) worm & wormwheel

c) bowl assembly

Q1. (a) What is meant by the term 'purification' and what does it 'separate'? (3)

(b) What are the basic methods of 'separation'? Explain the functioning of ‘purifier' and 'clarifier'? (3)

(c) What is meant by the term 'interface' and what is the role of 'gravity disc' in determining the same? (4)

(d) What is 'NOMOGRAM' and how is the correct 'gravity disc' size selected? (6)

Q9. With reference to centrifuges

a) How is the vertical Height is measured and why vertical Height of the spindle is so critical? (6)

b) Describe the troubles occurring on centrifuges during their operation and their rectification procedure. (10)

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)

Q2. (a) Explain the working principle of a fuel oil purifier. (8)

(b) Explain briefly the significance of the friction clutch mechanism. (4)

(c) List the alarms and trips associated with a purifier. (4)

Q8. With reference to a fuel oil purifier:

(a) What are the reasons that may cause the purifier to overflow? (6)

(b) What are the reasons for the water carry-over with the oil? (5)

(c) What are the probable reasons for vibration seen during purifier starting? (5)