DieselShip's Online Content Library

Q1. With reference to centrifugal pumps:

(a) (i) Sketch typical discharge characteristics showing variation of throughput as the

discharge head and speeds are altered; (4)

(ii) Explain why this characteristic profile is desirable; (4)

(b) Explain the relevance of discharge characteristic for the selection of an emergency

fire pump. (8)

Q9. Reverse osmosis is the contemporary alternative for shipboard production of drinking

a) Describe using simple diagrams where necessary, the principle of:-

i) Osmosis (3)

ii) Reverse osmosis (3)

b) Sketch a line diagram showing a ‘single pass system’ for producing fresh from seawater. (4)

i) Describe such a system. (4)

ii) State the safety features that may be incorporated into the plant. (2)

Q7. With reference to electric arc welding:

a) Draw a labeled sectional sketch of a satisfactory butt weld. (5)

b) Briefly define the following defects that may occur and how they may have been caused (6)

i) Under cut

ii) Splatter

iii) Inclusion

iv) Blow hole

v) Incomplete root penetration

vi) Lack of fusion

c) Why is alternating current generally more popular then direct current for metal arc welding? (5)

Q4. Sketch and describe an Independent two-stage air compressor. Draw a set of typical Indicator diagrams and insert the various pressures and temperatures. Indicate the effect of a leaking H.P. suction valve and excessive H.P. clearance volume. (16)

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.

Q6. State, with reasons, the causes of fatigue cracking of engineering components.

(a) State, with reasons, how material and design defects can Influence fatigue life.

(b) With reference to engine bed plate transverse girders explain how the Incidence of

fatigue cracking can be minimized. (16)

Q7. (a) Sketch in simple form a constant speed hele-shaw pump suitable for a hydraulic

steering gear. (6)

(b) Describe the pump and its principle of operation. (5)

(c) What characteristics of the pump make it suitable for use in steering gear system? (5)

Q8. (a) Describe the effects of freshwater feed on auxiliary boilers. (6)

(b) Describe the measures taken to reduce these effects. (4)

(c) Describe FIVE principle boiler water tests stating the reason for EACH. (6)

Q9. With reference to main refrigeration plants 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)