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Q7. With reference to the lubrication of refrigeration compressors:

(a) state the advantage of using fully synthetic oils; (2)

(b) explain why oil may be carried over from the compressor; (3)

(c) describe a device which returns oil from the compressor discharge to the compressor sump; (3)

(d) state TWO reasons why an accumulation of oil in the evaporator is undesirable. (2)

Q2. With reference to pneumatically operated control valves:

(a) state the reason for fitting valve positioners; (4)

(b) with the aid of a sketch, explain valve hysteresis and how it affects the process; (3)

(c) describe how the design and routine maintenance can limit hysteresis. (3)

Q8. With reference to fresh water HI-FOG fire fighting systems:

(a) sketch such a system; (6)          (b) state how the system in (a) is activated; (2)

(c) state, with a reason, a suitable location for the above system. (2)

Q3. (a) Explain how power is transmitted through main propulsion shafting. (3)

(b) State THREE operational factors that may induce high stress in shaft coupling bolts. (3)

(c) Sketch a hydraulic type of shaft coupling bolt. (4)