4. (a) Describe how unequal loading of main transmission shaft bearings may be partially corrected at sea.
(b) Suggest, with reasons, what remedial action should be taken upon arrival in port.
(c) State the indication, while at sea, that unequal loading of such bearing exists.
Class 3
1. How is alignment of a crankshaft checked? Does the loaded condition of the ship have any effect on alignment?
2. What are the forces on a diesel engine crankshaft and are these forces uniform along the length of the crankshaft? Give reasons for your answer.
3. What is the purpose of putting a thrust bearing between the main engine and the propeller? How is the thrust bearing cooled?
4. Explain how a variable pitch propeller operates.
Test Examples 7
Class 1
1. (a) Draw a line diagram of an accommodation air conditioning plant, labeling the principal components and showing the direction of air flows in all ducts.
(b) Explain why humidity control is essential for comfort.
(c) State how ambient temperature affects humidity control.
(d) Give a reason why compensation for air losses is necessary and how it is accomplished.
2. (a) Identify, with reasons, those properties of Freon which makes it such an attractive refrigerant.
(b) Give reasons why each of the following gases has fallen into disfavour as a refrigerant:
(c) Carbon dioxide
(d) Ammonia
(e) Methyl chloride
3. Give a reasoned opinion as to the validity of the following references to accommodation air conditioning:
(a) ‘Rule of thumb’ method whereby rate of air change is directly related to cubical capacity of the compartment concerned is quite satisfactory for all practical purposes
(b) Mechanical ventilation with air heating is inadequate for comfort in ships operating within a wide range of ambient air temperature and humidity
(c) Humidity control is absolutely essential for long-term comfort of personnel
4. In refrigeration define the following:
(a) specific heat capacity
(b) specific enthalpy of evaporation
(c) specific volume
(d) critical temperature
Give typical values for each of the above for three refrigerants
Class 2
1. (a) Draw a line diagram of a refrigeration system for servicing a large number of insulated containers labeling the principal items and showing the direction of flow in all lines and ducts.
(b) Explain how the system works in order to maintain containers at different temperature.
2. Suggest, with reasons, the most likely cause of the trouble if the suction to a multi-cylinder refrigerant compressor is subject to considerable icing under the following simultaneously prevailing condition:
(a) compressor in good condition and running at normal speed
(b) Throttling regulator valve open more than usual
(c) no detectable loss of refrigerant
(d) brine temperature rising
3. With reference to refrigeration plants answer the following:
(a) How are very low evaporator temperatures achieved?
(b) How are automatic expansion valves in direct expansion plants adjusted?
(c) How are compressors protected against appreciable ‘carry-over’ of liquid refrigerant?
(d) How is air in the system detected?
(e) How is over-charge of refrigerant indicated?
4. Briefly describe the following in main refrigeration plants:
(a) How can sea temperature restrict plant operation?
(b) How are the limitations in (a) overcome?
(c) How does short cycling occur?
(d) How is short cycling avoided?
Class 3
1. Sketch a simple refrigerant cycle of compression type plant. What kind of gas is commonly used in this type of plant?
a. A liquid
b. A gas
2. Describe the basic refrigerant circuit for a compression type plant. What kind of gas is commonly used in this type of plant?
3. State the reasons why Freon 12 is a popular refrigerant gas.
4. Explain why the refrigerant gas in a compression type domestic refrigeration plant is passed through a condenser after begin compressed
Test example 8
Class 1
1. Describe, with sketches, an inert gas system using gas from the main uptakes. Explain:
a. The scrubbing process and its purpose
b. Safety devices
2. Compare the advantages and the disadvantages of the following fixed fire extinguishing systems:
a. High-pressure water spray
b. Carbon dioxide smothering
c. Chemical foam smothering
3. Differentiate between fixed temperature and rate types of fire detector. Sketch and describe a fire detector of the rate of rise type and explain how a gradual rise of ambient temperature is accommodated.
4. With reference to fire or explosion explain the significance of the following properties of a flammable gas:
a. Combustion pressure
b. Explosive limits
c. Flash point
d. Density
5. Sketch the construction and describe the operation of the following types of fire detector:
a. Vapour product (ionisation)
b. Flame sensor (infrared)
c. Heat sensor (rate of rise)
Explain why use of all three types together is to be preferred to the use of one of these types alone.
Class 2
1. Compare with reasons the merits and demerits of the following permanent fire extinguishing systems installed in machinery spaces:
a. High-pressure water spray
b. Carbon dioxide smothering
c. Chemical foam smothering
2. Describe with sketches how the following portable fire extinguishers are operated:
a. Chemical foam
b. Carbon dioxide
Explain how they extinguish fire. State with reasons for what type of fire each is most suited for
3. Sketch and describe a self-contained breathing apparatus. Give two advantages and two disadvantages of this equipment compared to the smoke helmet. State the signal system used when wearing breathing apparatus. Describe with line diagrams a fixed carbon dioxide fire smothering system for an engine room.
4. Explain the need for an action alarm stating when and how it operates. Give a reason for gang release and explain how this is achieved.
5. If a fire broke out in the engine room, explain the following:
a. How can the fuel supply be shut off?
b. How can the supply of air be shut off?
c. How can the fire be dealt with from outside the engine room? Give a summary of all the facilities available for this purpose.
Class 3
1. Sketch a cross-section though a portable fire extinguisher suitable for use on oil fires. Identify the components.
2. State the component parts and associated equipment of a bellows type breathing apparatus.
3. Sketch and describe a smoke detector of the type fitted in an engine room. How is it tested?
Test examples 9
Class 1
1. Describe with a line diagram a hydrophore system, that is, a fresh water system incorporating an air reservoir.
Describe how a drop in pressure actuates the fresh water pump.
State two advantages of this system over the gravity head system.
2. Sketch a tubular oil cooler and explain the following:
a. How is differential expansion between the tubes and shell accommodated?
b. How is corrosion controlled?
c. How is automatic control of the oil temperatures effected?
State how by construction, operation and maintenance tube failure can be minimised
3. Give a simple explanation of the nature and effect of cavitation in rotodynamic pumps.
Describe with sketches a super-cavitating pump. State the purpose of such a pump and give an instance of current shipboard application.
4. Describe with sketches a centralised cooling system incorporating plate type heat exchangers.
Explain the purpose of this system and how it is achieved.
5. Describe with sketches an axial flow pump.
Explain its principle of operation.
State what important advantage and serious disadvantage it possesses compared to other pumps.
Explain the effects of throttling either the suction or discharge valve.
Class 2
1. Sketch and describe a plate type heat exchanger. State one advantage and one disadvantage of this design compared to the tubular type.
2. Sketch and describe a pump other than the reciprocating or centrifugal type.
Explain how it works.
State with reasons, the duty for which it is most suited.
3. Sketch and describe a centrifugal bilge pump.
Explain the need for a priming pump.
Give one advantage and one disadvantage of the centrifugal pump compared to the direct acting pump for bilge duties.
4. Sketch the construction of all oil-water separator.
Explain how it functions in service.
State the purpose and operation of all alarms or safety devices fitted to the separator.
5. Make a line diagram of a bilge pumping system for a dry cargo ship.
Indicate the type and position of each valve fitted.
In view of the possibility of collision, explain how the integrity of the bilge pumping system is ensured as far as possible.
Class 3
1. Make a diagrammatic sketch of a bilge pumping system itemising the main components.
2. Describe the passage of water through a centrifugal pump.
3. Describe an oil-water separator and state how you would check that it was working satisfactorily.
Test examples 10
Class 1
1. Describe a centrifugal oil purifier and explain in detail how separation occurs. Should a purifier be worked at its rated capacity if the maximum efficiency of separation is desired?
2. Sketch and describe a purifier and explain how the separation of dirt and water from oil is accomplished. What factors increase the speed and efficiency of the separation? Comment on the advantages and disadvantages of water washing lubricating oils.
3. Discuss the effects of water in lubricating oils and fuel oils. Explain how the presence of water can be detected and explain how water can be separated from oil by virtue of their different densities.
4. Sketch and describe three types of lubricating oil filters used aboard ship. Give reasons for using different types and relative positions in the system.
5. Explain the necessity for regular laboratory analysis of lubricating oils and the importance of obtaining a truly representative sample for this purpose. Without specialist equipment explain how to test for the following:
a. Sludge
b. Water
c. Acidity
State what effect each of these has on bearing
4. (a) Describe how unequal loading of main transmission shaft bearings may be partially corrected at sea.(b) Suggest, with reasons, what remedial action should be taken upon arrival in port.(c) State the indication, while at sea, that unequal loading of such bearing exists.Class 31. How is alignment of a crankshaft checked? Does the loaded condition of the ship have any effect on alignment?2. What are the forces on a diesel engine crankshaft and are these forces uniform along the length of the crankshaft? Give reasons for your answer.3. What is the purpose of putting a thrust bearing between the main engine and the propeller? How is the thrust bearing cooled?4. Explain how a variable pitch propeller operates.Test Examples 7Class 11. (a) Draw a line diagram of an accommodation air conditioning plant, labeling the principal components and showing the direction of air flows in all ducts.(b) Explain why humidity control is essential for comfort.(c) State how ambient temperature affects humidity control.(d) Give a reason why compensation for air losses is necessary and how it is accomplished.2. (a) Identify, with reasons, those properties of Freon which makes it such an attractive refrigerant. (b) Give reasons why each of the following gases has fallen into disfavour as a refrigerant: (c) Carbon dioxide (d) Ammonia (e) Methyl chloride3. Give a reasoned opinion as to the validity of the following references to accommodation air conditioning: (a) ‘Rule of thumb’ method whereby rate of air change is directly related to cubical capacity of the compartment concerned is quite satisfactory for all practical purposes (b) Mechanical ventilation with air heating is inadequate for comfort in ships operating within a wide range of ambient air temperature and humidity (c) Humidity control is absolutely essential for long-term comfort of personnel4. In refrigeration define the following: (a) specific heat capacity (b) specific enthalpy of evaporation (c) specific volume (d) critical temperature Give typical values for each of the above for three refrigerantsClass 21. (a) Draw a line diagram of a refrigeration system for servicing a large number of insulated containers labeling the principal items and showing the direction of flow in all lines and ducts.(b) Explain how the system works in order to maintain containers at different temperature.2. Suggest, with reasons, the most likely cause of the trouble if the suction to a multi-cylinder refrigerant compressor is subject to considerable icing under the following simultaneously prevailing condition: (a) compressor in good condition and running at normal speed (b) Throttling regulator valve open more than usual (c) no detectable loss of refrigerant (d) brine temperature rising3. With reference to refrigeration plants answer the following: (a) How are very low evaporator temperatures achieved? (b) How are automatic expansion valves in direct expansion plants adjusted? (c) How are compressors protected against appreciable ‘carry-over’ of liquid refrigerant? (d) How is air in the system detected? (e) How is over-charge of refrigerant indicated?4. Briefly describe the following in main refrigeration plants: (a) How can sea temperature restrict plant operation? (b) How are the limitations in (a) overcome? (c) How does short cycling occur? (d) How is short cycling avoided?Class 31. Sketch a simple refrigerant cycle of compression type plant. What kind of gas is commonly used in this type of plant?a. A liquidb. A gas 2. Describe the basic refrigerant circuit for a compression type plant. What kind of gas is commonly used in this type of plant?3. State the reasons why Freon 12 is a popular refrigerant gas.4. Explain why the refrigerant gas in a compression type domestic refrigeration plant is passed through a condenser after begin compressedTest example 8Class 11. Describe, with sketches, an inert gas system using gas from the main uptakes. Explain:a. The scrubbing process and its purpose b. Safety devices 2. Compare the advantages and the disadvantages of the following fixed fire extinguishing systems:a. High-pressure water sprayb. Carbon dioxide smothering c. Chemical foam smothering3. Differentiate between fixed temperature and rate types of fire detector. Sketch and describe a fire detector of the rate of rise type and explain how a gradual rise of ambient temperature is accommodated.4. With reference to fire or explosion explain the significance of the following properties of a flammable gas:a. Combustion pressure b. Explosive limits c. Flash point d. Density5. Sketch the construction and describe the operation of the following types of fire detector:a. Vapour product (ionisation)b. Flame sensor (infrared)c. Heat sensor (rate of rise)Explain why use of all three types together is to be preferred to the use of one of these types alone.Class 21. Compare with reasons the merits and demerits of the following permanent fire extinguishing systems installed in machinery spaces:a. High-pressure water sprayb. Carbon dioxide smothering c. Chemical foam smothering2. Describe with sketches how the following portable fire extinguishers are operated:a. Chemical foamb. Carbon dioxideExplain how they extinguish fire. State with reasons for what type of fire each is most suited for3. Sketch and describe a self-contained breathing apparatus. Give two advantages and two disadvantages of this equipment compared to the smoke helmet. State the signal system used when wearing breathing apparatus. Describe with line diagrams a fixed carbon dioxide fire smothering system for an engine room.4. Explain the need for an action alarm stating when and how it operates. Give a reason for gang release and explain how this is achieved.5. If a fire broke out in the engine room, explain the following:a. How can the fuel supply be shut off?b. How can the supply of air be shut off?c. How can the fire be dealt with from outside the engine room? Give a summary of all the facilities available for this purpose.Class 31. Sketch a cross-section though a portable fire extinguisher suitable for use on oil fires. Identify the components.2. State the component parts and associated equipment of a bellows type breathing apparatus.3. Sketch and describe a smoke detector of the type fitted in an engine room. How is it tested?Test examples 9Class 1 1. Describe with a line diagram a hydrophore system, that is, a fresh water system incorporating an air reservoir.Describe how a drop in pressure actuates the fresh water pump.State two advantages of this system over the gravity head system.2. Sketch a tubular oil cooler and explain the following:a. How is differential expansion between the tubes and shell accommodated?b. How is corrosion controlled?c. How is automatic control of the oil temperatures effected?State how by construction, operation and maintenance tube failure can be minimised3. Give a simple explanation of the nature and effect of cavitation in rotodynamic pumps.Describe with sketches a super-cavitating pump. State the purpose of such a pump and give an instance of current shipboard application. 4. Describe with sketches a centralised cooling system incorporating plate type heat exchangers.Explain the purpose of this system and how it is achieved.
5. Describe with sketches an axial flow pump.
Explain its principle of operation.
State what important advantage and serious disadvantage it possesses compared to other pumps.
Explain the effects of throttling either the suction or discharge valve.
Class 2
1. Sketch and describe a plate type heat exchanger. State one advantage and one disadvantage of this design compared to the tubular type.
2. Sketch and describe a pump other than the reciprocating or centrifugal type.
Explain how it works.
State with reasons, the duty for which it is most suited.
3. Sketch and describe a centrifugal bilge pump.
Explain the need for a priming pump.
Give one advantage and one disadvantage of the centrifugal pump compared to the direct acting pump for bilge duties.
4. Sketch the construction of all oil-water separator.
Explain how it functions in service.
State the purpose and operation of all alarms or safety devices fitted to the separator.
5. Make a line diagram of a bilge pumping system for a dry cargo ship.
Indicate the type and position of each valve fitted.
In view of the possibility of collision, explain how the integrity of the bilge pumping system is ensured as far as possible.
Class 3
1. Make a diagrammatic sketch of a bilge pumping system itemising the main components.
2. Describe the passage of water through a centrifugal pump.
3. Describe an oil-water separator and state how you would check that it was working satisfactorily.
Test examples 10
Class 1
1. Describe a centrifugal oil purifier and explain in detail how separation occurs. Should a purifier be worked at its rated capacity if the maximum efficiency of separation is desired?
2. Sketch and describe a purifier and explain how the separation of dirt and water from oil is accomplished. What factors increase the speed and efficiency of the separation? Comment on the advantages and disadvantages of water washing lubricating oils.
3. Discuss the effects of water in lubricating oils and fuel oils. Explain how the presence of water can be detected and explain how water can be separated from oil by virtue of their different densities.
4. Sketch and describe three types of lubricating oil filters used aboard ship. Give reasons for using different types and relative positions in the system.
5. Explain the necessity for regular laboratory analysis of lubricating oils and the importance of obtaining a truly representative sample for this purpose. Without specialist equipment explain how to test for the following:
a. Sludge
b. Water
c. Acidity
State what effect each of these has on bearing
การแปล กรุณารอสักครู่..
