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Q9. i) State the advantages and disadvantages in using centrifugal pump on ship’s duties. (4)

ii) How should a centrifugal pump be operated in order to get best results? (5)

iii) State maintenance schedule for the pump. What parts of the pump are closely checked during surveys? (7)

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)

Q2. (a) Why are centrifugal pumps used for the sea and cooling water services with marine diesel engines? What are their drawbacks? (6)

(b) What do you understand by the term 'pump characteristics'? (6)

(c) What is net positive suction head? (4)

Q7.a) Describe uses of packed gland seal, which all machinery they are in use? In a running pump, how the gland packing is lubricated and kept cool? (6)

b) Describe advantages of using gland packing. (5)

c) Describe disadvantages of using gland packing. (5)

Q2. Define the main purpose of the following with respect to tank and pumping system.
(a) Weighted cocks on tank sounding pipes (4)

(b) Remote operated gear for bilge valves (4)

(c) Ventilation pipes for double bottom tanks (4)

(d) Explain why gauze is sometimes fitted to tank ventilation pipes and explain the effect of mesh size. (4)

Q8. (a) Sketch a screw displacement pump and explain its operation (10)

(b) State the factors which affect its efficiency. (6)

Q1. With reference to centrifugal pumps and pumping systems. A) Under what conditions, a centrifugal pump require a priming device for pump to operate normally? B) Draw a neat graph and explain and the performance curves of a centrifugal pump.

Q5. A. Sketch a simple cross section through a single stage centrifugal pump with a fully shrouded single entry impeller, name the components of the pump and indicate the direction of fluid flow. B.  Describe: - i. The function of the impeller and how suction is created by it; ii. The function of the volute casing. iii. State the material of each component of the pump. C. State the suction lift that may be expected.; D. State why some centrifugal pumps have: - A double volute casing; (ii) A diffuser ring

Q5. i) Define ‘centrifugal pump’ and where it is used on ships? Using a simple line diagram show a circuit which include a centrifugal pump. Explain the meaning of ‘suction lift’. (6)

ii) Sketch and describe the construction of a centrifugal pump, labelling its parts. What is a ‘lantern ring’ and why is it fitted? (10)