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Q4. A distinguishing feature of an eductor, when compared to other pumps, is the (16)

(a) Discharge end being smaller than the suction end

(b) Small size of impeller

(c) Lack of moving parts

(d) Ease at which the wearing rings may be changed

Briefly justify your answer.

Q4. a) Whils't on ‘seawatch’ you observe that the Oil Mist detector (OMD) in the engine room has triggered an alarm, and in feeling the crankcase doors on the bottom platform, you find that the unit in question feels warmer than the rest. What pre-emptive action will you take as Watch-keeper to bring the situation under control. (10)

b) Draw a simple line diagram of an ‘OMD’ and explain it’s working. (6)

Q8.a) Sketch a two-ram type hydraulic steering gear with a single Electro-hydraulic pumping unit. Show the hunting gear arrangement and indicate valve positions. (8)

b) State the purpose of, and describe the operation of (8)

i) hydraulic shock/buffer valves.

ii) Oil replenishing tank.

iii) Hunting gear.

Q4) Describe with the aid of suitable graph, the discharge characteristics of a centrifugal pump. Explain why it does not require a relief valve (16)

Q5) With regard to a reciprocating refrigerator compressor.

(a) Sketch the mechanical shaft seal showing its component parts and how it is lubricated (8)

(b) Describe the sealing arrangement stating the materials used for the component parts (4)

(c) State the effect on the environment of the release of refrigerants into the atmosphere (4)

Q6) (a) Sketch an auxiliary boiler ‘blow down’ valve. Explain how it differs from its shipside counterpart (10)

(b) Describe the sequence of ‘blow down’ procedure (6)

Q7) Submit a report to the Chief Engineer stating how the freshwater generator output on board you ship was increased to near optimal values. The report should specifically mention the adjustments, corrections and improvements executed (16)