Oral examination for Third and Second Engineer
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Oral examination for Third and Second Engineer



Oral examination for Third and Second Engineer

Oral examination for Third and Second Engineer



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    Oral examination for Third and Second Engineer Oral examination for Third and Second Engineer Document Transcript

    • S e c o n d A ss i st an t E ng i n e e r (2A E ) DIESEL ENGINE 1. What happens when too much cylinder oil is injected in the working cylinder? Ans. . Color of exhaust gas is bluish. . Formation of carbon deposits on piston ring and ring grooves . Increase in cylinder oil co nsumption 2. Is the unit and normal value fuel ratio of an average diesel engine? Ans. G/psh 20 - 130g/psh 3. What is the formula for 1 HP of a two-cycle engine? Ans. IHP = PL AN c 33000 ft-LB/min 4. Name the indicator diagram. Ans. - Compression diagram - Out of phase diagram/draw card - 5. Power diagram Light spring diagram What are the 3 parts in indicator diagram? Ans. Maximum compression pressure, maximum combustion pressure, means effective pressure. Japanese Licensure Examination 1
    • 6. What are the causes of damage of diesel engine exhaust Valve? Ans. - Exhaust valve leakage - 7. Fuel contaminants ( Sulphur, Sodium, Vanadium) Erosion and Corrosion What are the causes of lO. high temperature in a diesel engine? Ans. - Clogged up cooling tubes - 8. Insufficient flow of cooling medium Incorrect opening of tempera ture control valve What trouble could result if the main engine is using a low grade of fuel? Ans. Inefficient combustion takes place -causing cylinder liner wear, exhaust valve wear, trouble with fuel injectors and prone to carbon build-up In the exhaust system. 9. What are the causes of liner high temperature? Ans. Engine is overloaded; insufficient lubrication 10. What happen when too much cylinder oil is injected in the working cylinder? Ans. Color of exhaust gas will be bluish. Excessive carbon depo sit 11. How many lubricating holes are there in cylinder? Ans. Approximately 8. Japanese Licensure Examination 2
    • 12. What are the defects in exhaust valves? Ans. - Excessive carbon residue at spindle - 13. Exhaust valve seat pitting/wear Erosion and corrosion How do you control cylinder liner wear? Ans. - Correct liner and piston ring clearances - Well maintained and timed fuel injectors - Proper fuel and LO treatment process - Usage of LO. with properties ( Total Base Number) - Correct scavenging air temperatures - 14. Sufficient lubrication Correct Cooling water an d lubricating oil temperatures How much is the specific fuel consumption of an average diesel engine? Ans. 120-130 G/PS-Hr 15. Purpose of lubricator in a large diesel engine. Ans. To pump oil into the cylinder passing a number of lubricating orifice during the upward stroke. 16. Explain how the cylinder lubrication on main engine is done? Ans. lubricators are usually supplied with oil from a day tank, The through a gravity, which equipped with a built in float, strainers and stop valves. The oil Is pumped into t he cylinder by lubricator pump via non-return valve, passing a number of lubricating orifice during the upward stroke. The oil feed rate or dosage Japanese Licensure Examination 3
    • should be in recommendation accordance and should with be the engine increased during builder's starting, maneuvering and large changes in engine load. 17. Explain the function of cooling water expansion tank. Ans. To maintain sufficient cooling water in the F.W.C. system by gravit y. To reduce air or steam pocket s Allow changes of the cooling water volume due to hea ting and cooling Maintains a constant head in the system 18. Explain the causes of the exhaust valve leakage. Ans. Corrosion/Wear of exhaust valve seat 19. What is the purpose of l.O. circulation before and after starting of engine? Ans . The purpose of l.O. circ ulation before starting of engine is to prevent seizure of metal parts especially the cylinder and the piston. While after stafting of engine and continuos running, is to prevent metal to metal contact and reduce friction and wear at a moving parts. It als o serves a cooling medium between metal parts. 20. Names of valve connected in cylinder head of the engine. Ans. 1. Relief valve 2. Fuel injector valve 3. Indicator valve 4. Starting air valve 5. Exhaust valve Japanese Licensure Examination 4
    • 21. Name the safety devices of diesel engine? Ans. 1. Relief valves fitted to the chamber to warn of excessive increase in combustion pressure. 2. Relief valves fitted to the crankcase to act, as safety valves should oil vapor ignite due, for instance, to a hot bearing. 3. Relief valves fitted to scavenge space s to protect the chamber against high pressure, 4. Relief valves for fuel pumps and fuel system to prevent line from bursting. 5. Relief valves for starting air system to prevent excessive pressure and flame traps or bursting disc at each starting air valve. 6. Interlocks fitted to turning gears to ensure that the engine cannot be started whilst the turning gear is engaged. 7. Automatic shut down of the engine due to low pressure in the lubricating or cooling system. 8. Automatic shut down of the engine due to high/low temperature in various systems. 9. Shut down the engine from the bridge should the communication with the engine room fail when the vessel is in hazardous posItion. 10. Over-speed trip which cuts the fuel supply to the engine should the main governor fail and the engine RPM increases. 11. Oil mist detector fitted in the crankcase to give warning of hot running parts. 12. A temperature probe system fitted to bearing to give alarm of excessive temperature. 13. A temperature probe system fitted in the scavenge air space to indicate scavenge fires. 22. What is injection lag? Ans. Japanese Licensure Examination 5
    • After compression fuel is injected and comes in contact with hot compressed air, total combustion of fuel does not occur instantly (time delay of ignition) due to the quality of IFO. 23. Explain how to measure crank web deflection? Ans. Crankshaft alignment can be checked by taking deflections. A Strain gage arrange horizontally between the crank webs opposite the crank pin and ideally at the circumference of the main journal will give horizontal deflection, wh en the crank is rotated through one revolution, that is directly proportional to the vertical deflection. be checked against Vertical and horizontal misalignment can the permissible values supplied by the engine builder. 24. In a 4cycle engine the intake val ve begins to open at ? Ans. Intake stroke 25. What causes cylinder liner - wear down? Ans. a. insufficient lubrication b. excessive load c. poor combustion d. incorrect L.O. properties used e. poor quality of fuel oil used 26. What causes diesel engine to automatically stop? Ans. a. Over speed b. Low L.O. pressure of System. Crosshead and cylinder L.O. c. Low pressure and high temperature of cooling water 27. What causes crankcase explosion? Ans. a. blowpast of hot gases inside the underpiston? Japanese Licensure Examination 6
    • b. Formation of flamm able vapor inside the crankcase c. Presence of hot spot inside the crankcase (Main Bearing) d. Excessive crankcase pressure 28. What do you call the clearing of air inside cylinder after combustion? Ans. Scavenging method ( Uniflow , Loop and Cross scavengin g) 29. What is the circulation of l.O. pump to diesel engine? Ans. Sump tank.. ~ Suction strainer ~L.O. pump ~ L.O. cooler ~ Aut o backwash filter L.O. ~ M/E 30. What causes diesel engine trouble when using heavy oil? Ans. a. poor combustion b. excessive formation of carbon deposits c. excessive corrosion and wear of engine parts d. high thermal load 31. What causes turbocharger surging? Ans. a. fouling of turbocharger b. rough sea condition c. contamination of exhaust and scavenging ducting ports and filters d. variation in gas supply to turbo charger due to unbalanced output. e. Mechanical damage in turbo charger 32. What pressure is highest L.O. Gravity Head or S.W. of the stern tube circulation Ans. Japanese Licensure Examination 7
    • Pressure of L. O. gravity tank 33. What is fuel catalytic cracking Ans. Method of separating fuel into different grades by the use of a catalyst. 34. Contaminants of fuel oil Ans. 1. Sodium - is contaminant which may be present due to seawater in the fuel. 2. Vanadium removed and by neutralized Sulfur the by - are purifier. alkali dissolved The effect additives in in of the fuel the diesel and sulfur engine can not be cylinder lubricants. 3. Silicon purifier and or aluminum clarifier I - catalytic but slow fines are throughout remove is in the essential for optimum results. 35. Crankcase oil mist detector Ans. it uses photoelectric cells to measure small increases in 011 mist density which is harmful and may lead to crankcase explosion. 36. Inspection for intermediate shaft bearing. Ans. Shaft bearings are of two types, the aftermost tunnel bearing and all others. The aftermost tunnel bearing has a top and a bottom bearing shell because It must counter act the propeller mass and take a vertical upward thrust at the forward end of the tailshaft. The intermediate shaft bearing only support the shaft weight and thus have only lower half bearing shell. lubrication is from a bath in the low er half of the casing and should be inspected. Also t he cooling process by water circulating through a tube cooler in the bottom of the casing. 37. What are the causes of main engine bla ck smoke? Ans. 1. Poor atomization of fuel Japanese Licensure Examination 8
    • 2. 3. Insufficient air (Restricted air Intake system) 4. Damaged piston rings and exhaust valve 5. low fuel oil pressure and temperature 6. 38. Damaged fuel injectors Fouled Exhaust gas Economizer Causes of emergency trip of diesel en gine Ans. 1. low lube oil pressure 2. Shut down of the engine from the bridge should the communication fail while the vessel is in hazardous position. 3. 4. Control air failure 5. 39. Over speeding, governor failure Jacket cooling water high temperature What are the causes if one cylinder In a diesel engine has a high temperature? Ans. 1. Damaged exhaust valves. 2. Poor jacket cooling in a single cylinder due to scale formation. 3. 4. Damage exhaust valve 5. Clogged scavenging port 6. 40. Damaged fuel injector nozzles. Excessive cylinder and piston ring wear Explain how the lubricating oil circulates in a diesel engine. Ans. Lubricating crankcase, for an known engine as the is stored pump, or in in a the bottom drain tank of the located beneath the engine. The oil is drawn from the tank throu gh a strainer, one of a pair of pumps, into one of a pair of fine filters. It is then passed to a cooler before entering the engine and being distributed to the various branch pipes. The branch pipes for a particular cylinder may feed the main bearing, fo r instance. Japanese Licensure Examination 9
    • Some of this oil my pass along a drilled passage in the connecting rod t o the gudgeon pin or crosshead bearing. An alarm at the end of the distribution pipes ensures that adequate pressure is maintained by the pump. Pumps and fine filters are arranged in a duplicate with one standby. The fine filters will be arranged so that one can clean while the other is operating. After used in the engine the oil drains back to a sump tank or a drain tank for reuse. A level gauge gives a local read -out of the drain tank contents. A centrifuge is arranged for cleaning the lubricating oil in the system and clean oil can be provided from a storage tank. The oil cooler is circulated by seawater, which is at a lower pressure than the oil. As a result any leak in t he cooler will mean a loss of oil and not contamination of the oil by seawater. 41. What are the causes of damage to propellers? Ans. ~ Cavitation - the forming and bursting of vapour filled cavities or bubbles, can occur as result of pressure variation at th e back of a propeller blade. ~ Corrosion ~ Small Cracks - due to loads and wears. ~ Grounding - this causes bents and worn out propellers. 42. What causes friction in the cylinder? Ans. 1. 2. Faulty combustion. 3. Used of incorrect cylinder oil. 4. 43. Inadequate or incorrect lubrication. Overloading of the engine. What causes damage to impellers? Ans. 1. Over speeding 2. Vibrations 3. Corrosion Japanese Licensure Examination 10
    • 4. 44. Wears In a four-stroke diesel engine, in what stroke exhaust valve will open? Ans. Exhaust Stroke 45. How is propeller fitted in shaft? Ans. The propeller is fitted unto a taper on the tailshaft and a key maybe inserted between the two; alternatively a keyless arrangement maybe used. A large nut is fastened and locked in place on the end of the taishaft; a cone is then bolted over the end of the tailshaft to provide a smooth flow of water from the propeller. 46. What valves are fitted in a four-stroke diesel engine? Ans. Exhaust valves and intake valves. 47. What are the automatic tripping devices of diesel generator? Ans. 1. Automatic shutdown of the engine due to high or low temperature in various systems. 2. Automatic shutdown of the engine due to low pressure in the lubricating or cooling system. 3. 48. Over speed trip What is the purpose of thrust bearing? Ans. Its purpose is to transmit thrust of the propell er to the hull to prevent the main engine from being forced out alignment. Japanese Licensure Examination 11
    • 49. What is fuel oil viscosity, specific gravity? Ans. Viscosity is the resistance to flow specified by Redwood Viscosity in Seconds being replaced by Kinematic Viscosity in Centistoke s. The specific gravity or relative density is the weight of a given volume of fuel compared to the weight of the same volume of water expressed as a ratio and measured at a fixed temperature. 50. What are the causes of low compression in the main engine? Ans. 1. 2. Damaged valves 3. Leaking cylinder head 4. Cam not in proper position 5. Restricted air passages 6. Back pressure of exhaust due to fouled Economizer 7. 51. Worn out piston rings. High scavenging air temperature What do you measure in the banana and mountain diagram? Ans. The relations of pressure and volume are measured in this indicator diagram. The compression, power and expansion curves are shown. 52. What is a brake horse power? Ans. The power developed by an engine as measured by the force applied to a friction brake or by an absorption dynamometer applied to the shaft or flywheel. Japanese Licensure Examination 12
    • 53. What are the requirements of a good fuel? Ans. The fuel oil must have a good viscosity at specific gravity. The ignition quality should have of higher value for better ignition. The flash point must be also obtained for maximum safe storage. The pour point and cloud point must be good. Low sulphur content to minimize engine wear. No water content and free from dirt and solid particles such as sand and small metal chips. 54. What is the purpose of a settling tank? Ans. The purpose of a settling tank is for fuel oil to settle down before it is drawn by purifiers and delivers it to the service tank. 55. What is the purpose of the turning gear? Ans. The purpose of the turning gear is to revolve the cr ankshaft of the engine while in stop position. This is done for the purpose of inspection and maintenance work. 56. What is the purpose of starting air? Ans. Starting air is used to initially turn the main engine and other auxiliary engine during starting by the use of pressurize air. 57. What is the purpose of engine preheating? Ans. The engine must be preheated to warm up the engine and reach the temperature at which it will be easier to start. This is done to avoid sudden rise of temperature during combustion which may result to thermal cracking and stress to the metals. Japanese Licensure Examination 13
    • 58. What is the purpose of air blow? Ans. Air blow is done to clear and check the combustion chamber from any leaks of jacket water and accumulation of moisture present before starting the engine to prevent for hydraulic knock. 59. What is the purpose of stern tube? , Ans. Stern tubes are constructed to secure an hold the tailshaft and prevent seawater from entering. 60. Where can you find thermometers in diesel engines? Ans. Thermometers can be found o n exhaust ports, jacket cooling lines, fuel oil lines and lubricating oil lines. 61. What would happen if there is air in fuel oil? Ans. a. Poor combustion fuel. b. Injection valve will not function properly. c. Air pocket . d. Damage to engine parts. e. Pulsation of fuel oil lines e. Stop or operate with reduced power f. 62. Failed to start What type of pump is lubricator pump? Ans. Positive displacement 63. What is the purpose of piston rings? Ans. Japanese Licensure Examination 14
    • The piston is so attached to the piston to prevent combustion gases to leak between t he cylinder and piston during combustion. To provide a gas tight sealing. 64. The advantage of a controllable pitch propeller? Ans. 1. 2. 65. It allows the main engine a single direction rotation. Fast action on reversing. Explain the fresh water cooling system s. Ans. The high temperature of the working cycle would quickly heat up the metal forming the cylinders, cylinder covers and pistons if steps were not taken to prevent this happening. It is necessary to keep the piston rings at temperatures sufficiently l ow for the lubricating oil surrounding them to survive and mechanisms such as fuel valves, exhaust valves and starting air valves must be kept at temperatures at which they will work satisfactorily and remain lubricated. Also the metal of parts forming the combustion spaces must be kept at a temperature low enough to avoid losing mechanical strength. The necessary control of temperature is carried out by the surrounding the cylinders with a jacket and by providing cylinder covers and pistons with passages t hrough which the cooling fluids maybe passed. The coolant is fresh water in the case of the cylinder covers. Pistons are cooled by fresh water in some designs and by lubricating oil in others. The heat picked up by these cooling fluids is transferred to seawater in heat exchangers and thus rejected to the sea, the cooling fluids becoming cooled and ready to circulate the jacket spaces again. Sea water cannot be used readily in the cooling spaces of modern engines as it Is both corrosive and liable to leave deposit s. OPEN AND CLOSED FRESH WATER SY STEM A fresh water system may be open or closed. In the open system water is drawn from a tank at atmospheric pressure, it is pumped through a heat exchanger (often termed the jacket water cooler) and then upwards th rough the engine emerging from the top of Japanese Licensure Examination 15
    • the engine. There are usually a number of outlets; one for each cylinder or cylinder cover and one for each piston if the pistons are water cooled. The cooling water spaces of turbochargers are usually included in the circuit also and will each have a water outlet. The water from these outlets is led to a hopper or tun dish which serves as a visual flow indicat or. At this point the wat er reaches atmospheric pressure again. Each tun dish is usually encased and viewed through a glass window in tne interests of safety and cleanliness. From here the water descends by gravity to the drain tank, the individual outlets usually being gathered together at a convenient point en -route. In the closed system there is no collectin g tank. The engine jackets, the heat exchanger and the pump form a continuous circuit which is not open to the atmosphere. However, provision has to be made for the expansion of the water due to the increase in temperature and due to small amounts of air w hich may enter the system and become entrained. These eventualities are met by a small header tank. The header tank is open to the atmosphere and place at a higher level than any other point in the system changes in volume can be accommodated by changing the level of the free surface of the water in the tank. The header tank is generally connected into the system at the pump suction, as this minimizes the chance of air being drawn into the system at the pump. With closed systems it is customary for the pump to circulate the water first to the engine jackets and then to the heat exchanger. The minimum height of the header tank may be based on maintaining pressure of fresh water in the heat exchanger above that of the sea water to ensure that in the event of a small internal leak developing sea water cannot enter the fresh water system. Alt ernatively, it may be based on the for a minimum pressure to be maintained within the jacKets to avoid cavitation effects. The maximum height of the header tank is determined by the pressure which joints and seals in the fresh water system can withstand. Open systems are self-venting but closed systems usually need vents if steam pockets or air locks are not to cause trouble. Vent pipes of small bore tube are lead from any loc al high point in the system to the top of the header tank so that the steam or air does not collect in these local high places. The temperature of the water entering the engine jackets is regulated by means of a by-pass across the heat exchanger. The propo rtion of water passing through the cooler, or by -passing it are controlled by a three way valve arranged either as a diverting valve if upstream of the heat exchanger, or as a mixing valve if downstream. The Japanese Licensure Examination 16
    • temperature is usually adjusted to maintain a co nstant outlet water temperature from the engine regardless of the load or speed or the temperat ure of the sea wat er. Almost alw ays t his is done automatically by using temperature sensitive controls for the valves. Fuel Injector valves require precise contr ol of the temperature at the tip of the nozzles; too high a temperature leading to the formation of carbon corrosion. They are trumpets, generally too Iowa provided temperature with a causing cooling water system which is either a branch of the jacket wate r system or an entirely separate circuit. In either case there will be a separate heat exchanger or a cooling tank and some means of adjusting, or at least setting, the rate of flow to the injector which is independent of that flow to the engine cylinder jackets. 66. What are the typical indicator diagrams? Ans. The power and draw cards should be closely studied. Diagrams given are for compression ignition engines of the 2 and 4 stroke types. Pressures and temperatures are shown on the sketches where appropriate. The draw card is an extended scale picture of the of the combustion process. In early marine practice the indicator card was drawn by the hand -hence the name. In modern practIce an 'out of phase' (90 degrees) cam would be provided adjacent to the general indicator com. In correct combustion details show readily on the draw card. There is no real marked difference between the diagrams for 2 stroke or 4 stroke. In general the compression point on the draw card is more difficult to detect on the 2 strok e as the line is fairly continuous. There is no induction - exhaust loop for the 4 stroke as the spring used in the indicator is too strong to discriminate on a pressure difference of say 1/3 bar only. With the fuel shut off expansion and compression shoul d appear as one line. Errors would be due to a time lag in the drive or a faulty Indicator com setting or relative phase difference between camshaft and crankshaft. Normally such diagrams would only be necessary on initial engine trials unless loss of comp ression or cam shift on the engine was suspected. Japanese Licensure Examination 17
    • 67. What is the trunk type and crosshead type piston Ans. Trunk type - work done in the piston is directly transmitted to the crankshaft Crosshead type - the piston is connected to a vertical member, the lower end of which is attached to a sliding member called a crosshead. It moves up and down in guides and is connected on the lower end of the connecting rod. 68. What is higher IHP or BHP Ans. IHP is always higher than BHP 69. What is the sensitive part of the li ner Ans. The upper most portion of the liner is the most sensitive part. It is where high pressure and temperature occurs. 70. Discuss how to prepare the M/E in standby condition Ans. I. Before a large diesel is started it must be warmed through by circulating hot water through the jackets, etc. This will enable the various engine parts to expand in relation to one another. 2. The various supply tanks, filters, valves and drains are all to be checked. 3. The lubricating oil pumps and circulating water pumps are started and all the visible returns should be observed. 4. All cont rol equipment and alarms should be examined for correct operation. 5. The indicator cocks are opened, the turning gear engaged and the engine turned Japanese Licensure Examination through several complete 18
    • revolutions. In this way any. water which may have collected in the cylinders will be forced out. 6. The fuel oil system is checked and circulated with hot oil. 7. Auxiliary scavenge blowers, if manually operated, should be started. 8. The turning gear is remov ed and if possible the engine should be turned over on air before closing the indicator cocks. 9. The engine is now available for standby. The length of time involved in these preparations will depend upon the size of the engine. 71. Explain now to clean LO Ans. L.O. requires treatment before passing to the engine, This will involve storage and heating to allow separation of water present, coarse and fine filtering to remove solid particles and also centrifuging. 72. Explain the principle of Sulzer Fuel oil inj ection pump Ans. Sulzer engines are provided with a fuel pump of timed double valve type, driven by the camshaft. Each pump consists of a plunger and guide bush and a driving piston. The roller is kept in contact with the cam by a powerful spring. A fuel p ump can be taken out of service by a mechanical cut -out lever, which lifts the driving piston and roller clear of the cam. This lever can also be used for priming the injection system. The fuel pump delivery is controlled by suction and spill valves. As the suction valve remains off its seat no fuel is delivered. When the fuel pump plunger is raised, the suction valve is low ered on t o it s seat . As soon as the suction valve closes, fuel is delivered. effective Normally stroke is the start controlled of delivery by is adjusting constant the and spill the valve. Retarding the spill valve increases the effective delivery stroke, while advancing reduces the effective stroke. These adjustments must be made when the engine is stopped and never when running. Ignition pressures are equalised only by turning the cams Japanese Licensure Examination 19
    • and not by altering the length of the pushrod. The fuel charge for individual cylinders can be temporarily reduced, for instance when running in a spare part such as a liner or piston, etc. by fitting a spacer between the pushrod and the regulating rod. This raises the suction valve by 2.4 mm. When adjusting the fuel pump control valves no spacers should be fitted. 73. What is the volume develop by the piston from BDC to TDC Ans. Swept volume is volume swept by the piston from BDC to TDC 74. Enumerate some trouble of fuel injection valve Ans. - stuck-up needle - 75. leaking F.O. injection valve clogged up atomizer Causes of M/E high exhaust valve temperature Ans. - leaking hot combustion gas - Incomplete combustion leading to high exhaust temperature I 76. . Insufficient cooling of valve seat What is the purpose of scrapper ring Ans. Scrapper ring distributes the cylinder oil injected in the surface of the cylinder. 77. What are the items to inspect after cylinde r liner is pulled out Ans. - corrosion of the flange - circumferential crack of the fillet shoulder Japanese Licensure Examination 20
    • - longitudinal crack of the inside of liner - crack on corner of the oil hole and oil groove - crack and corrosion of cooli ng surface - condition of liner surface - condition of lubrication - 78. wear down and corrosion of sliding surface cylinder liner wear What resistance the ship encounter when the vessel is at sea Ans. - Hull resistance due to marine growth - 79. Wave resistance Weather (rough wind and sea condition) What will you do in case of scavenging fire Ans. - When alarm has been given, the speed of the engine should be reduced to slow and fuel cut off to the particular cylinder. The cylinder oil supply should be maintained or even increased. - The bridge must be informed and permission to stop requested. Cut out fuel priming pump. Personnel must keep clear from equipment doors is and fitted relief to the valves. air Where receiver this fire -fighting should be brought into operation as soon as possible. If no equipment is available the fire will generally subside in about five to fifteen minutes. - Do not open scavenge space doors or crankcase doors before the site of the fire has cooled down. When opening up care must be taken to keep cleat of any flame. - After opening up all scavenge spaces must be thoroughly cleaned and all debris removed. - The piston rods and cylinder liner should be examined for surface blemishes, straightness etc., and the diaphragm glands examined to ensure that they are operational and not damaged. Japanese Licensure Examination 21
    • If possible the piston head in question should be renewed - at the earliest possible moment and the damaged unit overhauled. On engines fitted with tie bolts it may be necessary to re - - tighten the bolts adjacent to the fire. The - flat examined surfaces for of the distortion as scavenge alignment space of should the be camshaft bearings and the cylinder liners etc may be affected. When starting the engine again care must be taken after - switching on the fuel to the cylinder in question that the cylinder lubricating oil quantities are reduced to normal. Due to the large volume of air being blown through the receiver the formation of an explosive gas/air mixture Is extremely improbable. Conscientious - maintenance of the engine and regular inspection and cleaning of the scavenge air spaces will help to eliminate scavenge fires. 80. . Draw the flow of F.O. diagram from service tank to main engine? Ans. 81. What are the types of cleaning main engine Turbo charger blower side? Ans. ~ Water washing 82. What are the causes of main engine Turbo Charger blower side dirty? Ans. ~ Poor combustion due to low grade fuel ~ Damaged air filter 83. . Sketch the jacket coling system. Ans. Japanese Licensure Examination 22
    • 84. What will cause if you run your engine in critical RPM continuously? Ans. It affects the torsional load resulting to torsional vibration. The first mode of torsional vibration in the shafting system will have to noode and the highest torsional alternating stresses occur immediately aft of propulsion of the engine, for vessels with fairly long runs shafting, the first mode frequency usually occurs at a low shaft rpm. 85. What are the properties of fuel oil? Ans. ~ Sulfur - is present in most crude oils to varying degrees and is chemically bound in the fuel, the higher viscosity residual fractions tend to have higher sulfur contents. ~ Carbon residue - is the percentage of coked material remaining the sample of fuel oil has been exposed to high temperatures. Carbon reach fuels are more difficult to burn and therefore, have poor combustion characteristics which lead to the formation of soot and carbon deposits. Since carbon deposits can be major source of abrasive wear, the fuel carbon residue value may be an important parameter in the operation of a diesel engine. ~ Asphalt enes - are those component s of asphalt that are insoluble in petroleum ~ Naphtha but are soluble in carbon disulfide. They can be hard and brittle, are made up largely of high molecular weight, polynuclear hydrocarbon derivatives containing carbon, hydrogen, nitrogen, oxygen, and usually one or more of the three heavy metals - nickel, iron, and vanadium as well as sulfur. ~ Compatibility become cutter more stocks - is very intensely of important refi ned, light the distillate fuel quality, resulting to as fuel produce a is residual blended usable oils with handling characteristics. When light fractions with predominance of aliphatic hydrocarbon are mixed with a heavy fuel, the collidal dispersion of high molecular weight substances is disturbed. Due to this loss of equilibrium, the heavier constituents tent to precipitate, This is usually Japanese Licensure Examination 23
    • seen as sludge formation, causing clogged strainers and fouled filters and purifiers. ~ Vanadium - is a metallic element that is che mically bound in oil in the form of a soluble organometallic compound. The vanadium levels in residual fuels vary widely, depending the origin of crude oil, when present in critical amounts which vary with temperature involved, it forms adherent slag on high temperature surface, which include the super heater tubes in steam plant boilers and the exhaust valve and seats in valved diesel engines, as well as piston crowns, causing localized hotspot and eventual burning of high temperature surfaces. ~ Nickel - is another metallic element that is found in heavy crude oils, but in smaller amounts than vanadium. When compared to vanadium the combustion problems associated with nickel are minor. ~ Sodium - is an alkaline, metallic element that is found only in combined form, one of which is common salt, sodium salt (NaCI). Most sodium compounds are water soluble. Sodium found in fuel can come several sources but most of it is a direct result of storing and handling procedures from the time fuel leaves the refinery u ntil it is delivered to bunkers. Salt water contamination in barges used to transport fuel is not uncommon, to some extent even salt air condensation in fuel tanks contributes to a fuel overall sodium content. Regardless of the manner of contamination, sod ium in fuel is usually water soluble and can therefore, be removed with the water by a centrifugal separator. ~ Ash cont ent - The ash content of a fuel oil is a measure of the metallic content and the noncombustible inorganic solid contamination in the fuel. The ash content specially of heavy fuels, provides a method of assessing the quality of fuel oil and takes into account dispersed characteristics and dissolved such as solid compounds foreign metals of materials such as and the vanadium, sodium, iron and nickel. ~ Oxidation stability, products especially - Residual when fuels maintained may in a have a heated poor storage condition for ext ended periods of time. As fuel ages it becomes oxidize by air and begins to polymerize, forming sludge, gums, and res ins that can foul filters and heaters and can sometimes cause fouling of the injectors, combustion chambers, and exhaust system. Oxidation products can remain soluble in the fuel or become insoluble and precipitate out, forming an organic sediment. ~ Sediment - in fuels consists of insoluble matter, which may include sand, rust, and catalytic fines such as tar like polymerized hydrocarbons and precipitated asphaltenes, both of which break down Japanese Licensure Examination 24
    • under the heat of combustion and form lacquer and tarry deposits that impair the movement of parts and sometimes interfere with fuel nozzle spray patterns. Sediments containing abrasive materials or large amount organic materials can damage high pressure fuel pumps and fuel nozzles. Sediments are removed by centrifuges and filters. 86. What will you check if one cylinder of your engine is not like the others? Ans. ~ Exhaust temperature ~ Jacket cooling water outlet temperature ~ Fuel pump rack scale ~ Fuel injection timing ~ Fuel injector atomization and opening pressure ~ Check Pmax and Pcom 87. What do you do when in your duty, ME alarm oil mist detect high density? Ans. ~ Reduce speed to slow down level ~ Ask the bridge for permission t o st op ~ When engine stop order is received, stop the engine and close the fuel oil supply ~ Switch off the auxiliary blowers ~ Open the skylights and/or store hatch ~ Leave the engine room ~ Lock the casing doors and keep away from them MEASURES TO BE TAKEN WHEN OIL MIST HAS OCCURRED: ~ Don't stand near crankcase doors or relief valves nor in the corridors in the engine room casings. ~ Don't open crankcase until 30 min. after stopping the engine. ~ When opening-up keep clear of possible spurts of flame and avoid naked lights. Japanese Licensure Examination 25
    • 88. Classification of bunkers? Ans. ~ Specific gravity at 15 deg centigrade ~ Flashpoint ~ Viscosity ~ Water content ~ Sulfur content ~ Temperature 89. What is the purpose of increasing the pressure on the F.O system of the engine? Ans. To open the fuel oil injector to the desired opening pressure for good atomization. 90. What are the advantages of white metal? Ans. ~ Easy to manufacture ~ Relatively cheap ~ Uniform microstructure ~ Good bearing surface ~ Good anti frictional properties 91. What is the use of white metal? Ans. Production of: ~ Main bearing ~ Bottom end bearings ~ Stern tubes ~ Propeller shaft bearings ~ Crosshead and top end bearings 92. What is the cause of cylindrical liner overheating? Japanese Licensure Examination 26
    • Ans. ~ Too high thermal load or overloading ~ Lack of cylinder lubrication ~ Faulty injector nozzles 93. What are you going to inspect or check when you open the crankcase? Ans. ~ Check the tension of all bolts and nuts ~ Check the presence of cracks on engine frame ~ Check the presence of foreign matters and particles of metal in the crankcase ~ Visually check the oil circulation for bearings and gears ~ Check the camshaft driving gear 94. Draw L.O. system in diesel engine Ans. 95. What is the specific gravity of F.O and C.O? Ans. ~ F.O - .9 to .9 grams !cubic centimeter ~ 0.0 - .85 grams! cubic centimeter 96. What is pou point? Ans. This is a determination of the lowest temperature value at which oil will pour or flow under the prescribed test condition. 97. What is flashpoint? Ans. Japanese Licensure Examination 27
    • Is the minimum temperature at which enou gh fuel vapors will exist to support momentary combustion when an ignition source is present near the fuel surface. 98. What materials are used for engine propeller? Ans. ~ Copper base alloys ~ Manganese bronze ~ Nickel aluminum bron ze ~ Manganese nickel aluminum bronze 99. How fuel oil consumed by medium engine? Ans. 30 metric tons 100. What is the remedy if due exchanging, valve broke out during engine running operation? Ans. ~ Cut off the fuel pump by li fting and securing the roller guide ~ Put the exhaust valve out of action so that the valve remains closed (lift the guide or stop the oil supply and remove the hydraulic pipe) Spring air to be supplied. 101. At 50 Centigrade (Fuel oil) what is its cst? Ans. 380 Cst 102. At 50 Centigrade (Diesel oil) what is its cst? Ans. 180 Cst 103. What do you call a piston travel from TDC to BDC? Ans. Piston displacement Japanese Licensure Examination 28
    • 104. What happened if the exhaust valve is leaking ? Ans. ~ Low combustion pressure ~ High exhaust gas temperature 105. Why and what cause of leak fuel oil in high pressure pipe of main engine? Ans. ~ Vibration of engine ~ Material fatigue/cracks ~ Lack of tightening torque ~ Unbalanced tightening ~ Unequal surface between metal contact 106. What device installed in the F.O system when excess oil return to drain tank? Ans. Fuel oil backwash filter / Main engine 2nd and 3rd Filter 107. What parameters to be reported when we send lubricating oil for shore analysis? Ans. ~ Lubricating oil running hours ~ Viscosity ~ Sampling point or origin of oil ~ Type or grade of oil 108. Heavy fuel oil sulfur content and counter measures? Ans. 4% sulfur Counter measures ~ Use of cylinder oil with TBN to neutralize the formation of acids Japanese Licensure Examination 29
    • ~ Avoid low combustion temperat ure and eventually leads t o excessive liner wear ~ Maintaining the surface temperature of cylinder liners an d valves stems sufficiently high to prevent sulfuric acid condensation. ~ Lubricating oil analysis program is required to assured a correct acid /alkaline balance that provides the resistance to low temperature corrosion. 109. What will happen when engine stays in critical speed of 58 - 65 RPM? Ans. Torsional vibration 110. What are the causes of L.O. high temperature? Ans. ~ Fouled cooler ~ Hunting of control valve ~ Insufficient cooling water volume ~ Overloading 111. How to detect starting valve leaks? Ans. ~ Feel over method, by touching the starting air inlet pipe 112. What are the causes of dirty lubricating oil? Ans. ~ Prolong blow by ~ Centrifuge not working properly ~ Too much carbon in suspension ~ Dilution of fuel oil ~ Ineffective sealing on stuffing box (worn out) 113. Identify the parts of indicator diagram? Ans. Japanese Licensure Examination 30
    • 114. What are the symptoms of broken piston ring? Ans. ~ Prolong blow by ~ Low Pmax ~ Low Pcom ~ High exhaust gas temperature ~ Higher scavenge air box temperature 115. How much pressure on air reservoir? Ans. ~ 25 bar ~ 30 bar 116. Name the parts of piston through connecting rod? Ans. ~ Piston crown ~ Piston skirt ~ Piston pin bushing ~ Piston pin ~ Connecting rod ~ Connecting rod big end ~ Journal bearing 117. What are the causes of positive and negative propeller slip? Ans. ~ Weather condition ~ Wind force direction ~ Direction of current ~ Condition of hull 118. What will be the cause of scavenging fire? Japanese Licensure Examination 31
    • Ans. If flakes of burning carbon deposits drop into the oil sludge at the bottom of the scavenging air box, this sludge can be ignited and if very combustible material is found here, serious damage can be done to the piston rod and scavenge air box walls, the latter possible causing the reduction in the tensile of the stay bolts. ~ Prolong blow-by ~ Slow combustion in the cylinder, owing in"torrect atomization ~ Blow back through the scavenge air ports or large resistance to then exhaust system(back pressure) 119. What will you do when scavenge fire happened? Ans. ~ Reduce speed to slow and ask bridge for permission to stop ~ When the engine stop order is received, stop the engine and switch the auxiliary blowers ~ Stop the fuel oil supply ~ Stop the lubricating oil supply ~ Put the scavenging air box fire extinguishing equipment into function ~ Remove any deposits and sludge from all the scavenge air boxes ~ Clean respective piston rods and cylinder liners and inspect if in order 119. What are you going to observe, when a diesel engine is ru nning? Ans. ~ Lubricating oil pressure ~ Exhaust gas temperature ~ Jacket outlet/inlet temperature ~ Lubricating oil temperature in and out ~ Scavenging air pressure and temperature ~ Fuel pressure ~ Cylinder oil glass indicators ~ Turbo charger rpm ~ Load indicator Japanese Licensure Examination 32
    • ~ Piston cooling lubricating oil temperature outlet ~ Exhaust valve opening and confirm rotation ~ Starting air line pipe if increased in temperature 120. Where is the expansion tank located? Ans. At t he t op most portion of the engine room How the FCW system of diesel engine circulate? The cooling water system is divided into two lines, the jacket line and the cooler line. The standard cooling med ium used for jacket line is fresh water temperature jacket and control that valve for the controls cooler the line is jacket sea water. cooling The outlet temperature by passing or by passing the fresh water cooler. 121. What is mean effective press? Ans. The positive work done in one cycle of operations by the gas during the burning period and expansion of the gas. How to get MEP ~ By finding the area of the banana with the use of PL ANI METER ~ Area multiplied by the spring consta nt of mechanical indicat or Or ~ Divide the banana of equal coordinates ~ Measures the height ~ Add and find t he average or mean height ~ Mean height multiplied by spring constant of mechanical indicator 122. Draw a crankshaft and show the parts? Ans. 123. What is the lower part of connecting rod? Ans. ~ Crankpin bearing cap Japanese Licensure Examination 33
    • 124. What should you do before you start the engine? Ans. ~ Pre heat the engine ~ Make sure that lubricating oil is p roperly distributed to its system ~ Turn the flywheel with turning gear and lubricate cylinder liner ~ Blow off to make sure free of water in the cylinder 125. When you will install a new piston ring, what will be the position of it? Ans. The ends of the piston ring should not be in line or in other words it should be opposite to each other to prevent blow by or gas escaping to its end 126. What is max pressure? Ans. ~ The increase in pressure during the burning of fuel being injected to the cylinder utilizing the heat of compression 127. What are the things to do when approaching the port? Ans. ~ 12 hours before test steering gear ~ start another generator for power reserved ~ stand by boiler ~ reduce rpm until harbor speed ~ stand by engine ~ test main engine ahead and astern 128. What will be the cause of the loose compression in a cylinder? Ans. ~ Worn out piston ring ~ Worn out liner Japanese Licensure Examination 34
    • 129. What is the maximum P-max for a cylinder in M/E. Ans. 120-125 bar 130. What is the indication of leaking starting valve of an engine? Ans. Increased in temperature of starting air pipe 131. What is the thermal efficiency of a diesel engi ne? Ans. The thermal efficiency of an engine is the relationship between the quantity of heat energy converted into work and the quantity of heat energy supplied Thermal Efficiency = Heat energy converted into work Heat energy supplied 132. What will be the cause of high temperature in one cylinder ofD/E? Ans. ~ Defective fuel oil injector ~ More volume of fuel/rack adjustments ~ Injection timing ~ Leaky exhaust valve Second Assistant Engineer (2AE) AUXILIARY MACHINERY 1. Give five parts inside the centrifugal pump and explain each? Ans. For example, vertical single-stage single-suction centrifugal pump: Impeller – is of the single suction type and the balance holes provide near the center of the back should serve to cancel the axial thrust due to the pressure water on the back of the impeller. Japanese Licensure Examination 35
    • Pump casing – The volute casing is split into two halves along the vertical plane containing the axis, and the removal half casing can be removed easily without disturbing the suction and discharge pipes, both of which are provided in the stationary half casing. Stuffing box seal – This pump can be provided with either mechanical seal or gland packing for stuffing box sealing, which is its important part. Gland packing pressure – of carbon fiber is provided and sealed by water from discharge side. Mechanical packing – unbalanced type mechanical seal is fitted and flushed by pressure water from discharge side same as gland packing. Bearing - For the upper ball bearing is furnished to support the rot ating element . Alt hough it is fitted int o the solid inner case, it can be taken out together with the rotating element if the bearing housing cap is removed. It is grease lubricated. The lower bearing is a line bearing fitted in the volute casing. For the bearing material, lubrication is good effected self-lubricating by means of the ability is pump’s used and discharged pressure water. Impeller shaft – serves as the rotating element of the pump. 2. What type of gear is the first reduction gear pinion? Ans. Helical gear 3. List the main parts of a Centrifugal pump Ans. - impeller - shaft - bearing, - mouth ring, - volute casing. Japanese Licensure Examination 36
    • 4. Enumerate the causes of pumps low delivery of water Ans. – air leakage – speed too low – suction lift too high – – impeller clogged – impeller and mouth ring clearance is bigger – 5. discharge head too high cavitation due to high liquid temperature. What type of pump is main L.O. pump? Ans. Positive Displacement Screw -type rotary pump 6. How to shut down and overhaul the centrifugal pumps? Ans. 1) Stop the pump by switching off the electric motor 2) Switch off the circuit breaker and put a notice pump is to 3) be overhauled like “warning”. On motor, that the electric disconnect the 3 -phase wiring and draw-out the said motor. 4) Draw-out the pump and start dismantling sequentially, e.g. according to part number and the like. 5) Check for wear and replace with new spare, check clearance between the mouth ring and impeller (should be within the manufacturer’s specific ations). Clean parts such as casing, gland and so on. 6) Assemble the pump and mount with the electric motor. Perform coupling alignment to avoid vibration. 7) Connect the electric motor wiring and start the pump by putting “on “ the power source. Visu al check its condition as well as feeling any abnormalities while operating. 7. What is the specific gravity or relative density of fuel oil? Ans. Japanese Licensure Examination 37
    • Specific gravity is the ratio between the density of fuel oil to the density of standard substance water which is 1. 8. Properties of F.O. that cause damage on auxiliary boiler. Ans.   sulfur content  9. Ash content water content Device use to control flow rate of centrifugal pump. Ans. In controlling flow rate of centrifugal pump, discharge valve should be throttled. 10. What is the use of gravity disc? Ans. Gravity disc is responsible for the setting or positioning of the interface at the outlet of the centrifuge. Various diameter rings are available for each machine when different densities of oil are used. As general rule the largest diameter ring which does not break the seal should be used. 11. What causes damage to impellers? Ans. 1. 2. Vibrations 3. Corrosion 4. 12. Over speeding Wears Give the procedures in starting centrifugal pumps. Ans. Open the air cock at the top of the casing and turn over the impeller a few times by hand. Close the discharge valve and prime the pump. Japanese Licensure Examination 38
    • Start the pump by pushing the motor switch or by starting its turbine. As soon as impeller began to turn, close the priming connec tions. When pump is running at full speed, open the discharge valve gradually. Examine bearings to check operation of automatic oilers. 13. How to stop a purifier? Ans. 1. 2. Stop the fuel oil feed pump. 3. Close the fuel oil inlet outlet valves. 4. 14. Manually push the Auto-stop button in the controller Secure heater ( steam in and out ) What type of pump is /are commonly used in auxiliary boilers? Ans. Centrifugal pumps 15. Explain the operation of a centrifugal purifier. Ans. The centrifugal operation of two liquids, such as oil and water, results in the formation of cylindrical interface between the two. The positioning of this interface within the centrifuge is very important for correct operation. The setting or positioning o f this interface is achieved by the used of dam rings or gravity discs at the outlet of the centrifuge. Various diameter rings are available for each machine when different densities of oil are used. As a general rule, the largest diameter ring, which does not break the seal, should be used. 16. How would you increase the volume efficiency of a centrifugal pump? Japanese Licensure Examination 39
    • Ans. Centrifugal pump volume efficiency can be increased by fully opening the discharge valve. 17. What is fuel oil viscosity, specific gravity? Ans. Viscosity is the resistance to flow specified by Redwood Viscosity in Seconds being replaced by Kinematic Viscosity in Centistokes. The specific gravity or relative density is the weight of a given volume of fuel compared to the weight of the same volume of water expressed as a ratio and measured at a fixed temperature. 18. What type of pump is lubricator pump? Ans. Positive displacement 19. Identify or enumerate the parts of stern tube Ans. 20. Explain how to adjust pump pressure Japanese Licensure Examination 40
    • Ans. Pump pressure can be adjusted by throttling the discharge valve, controlling the 21. speed What is absolute pressure Ans. Absolute pressure is the true pressure and can be found by the following formula Absolute pressure Absolute pressure 22. = gage pressure - atmospheric pressure = atmospheric pressure - vacuum Purpose of stern tube sealing Ans. The purpose of stern tube sealing is to prevent the ingress of sea water to the engine room. 23. What is white metal Ans. White metal is the most common type of bearing employed in slow speed diesel engine because of their ability to absorb particles of dirt, ease of manufacture and relative cheapness. 24. What is compound gage Ans. Compound gage is an instrument which measure s both the vacuum and pressure. 25. What are the safety consideration in welding job? Ans. ~ wearing of protective clothing ~ proper usage of welding equipment Japanese Licensure Examination 41
    • 26. Explain the procedure in starting a F.O. purifier Ans. 1. Open the water supply valves and make sure that the water supply is on 2. Start the separator 3. Be alert on unusual noise and conditions 4. Check the current to the separator motor to ensure that the separator has reached full speed 5. Supply water to form the water seal 6. Close the water feed when water flows out through the water outlet 7. 8. Fill the bowl as quickly as possible 9. 27. Start the oil feed slowly to avoid breaking the water seal Adjust to the desired throughput What is a manometer and give an example of its application Ans. An instrument use to measure low pressure readings, can be commonly applied in economizer differential pressure. Air cooler and turbocharger air filter 28. What is acceleration Ans. Time rate of change of velocity 29. Enumerate or identify the parts of Japanese Licensure Examination purifier bowl assembly 42
    • 30. What are the types of pump can be found in the engine room Ans. Centrifugal pump, screw pump, reciprocating pump, vane pump, axial pump, rotary pump, 31. What is an oil mist detector Ans. An instrument use t o detect the formation of flammable vapor inside the crankcase 32. What type of metal is used in a propeller Ans. Manganese bronze 33. What is the purpose of safety valve Ans. To relieve the system of excess pressure 34. What is the purpose of gravity tank in the stern tube Ans. To maintain a good sealing condition by providing a head pressure to give adequate sealing force. 35. Explain the opening and closing of water to the bowl of the purifier Ans. Water in the operating chamber, builds up a pressure due to centrifugal force (despite small loss through the drain nozzl e) which pushes the operating Japanese Licensure Examination slide down against the springs 43
    • beneath it. As soon as the operating slide begins to move downwards, the drain holes open and the high pressure operating water under the sliding bowl escapes rapidly. Pressure exerted by liquid in the bowl forces the bottom down and solids are discharged through the ports. When all of the operating water has drained from the underside of the sliding bottom and discharge of solids is complete, then with the solenoid valve closed the operating slid e is moved back up by the springs to close the drain holes. To raise the sliding bottom, the chamber under it must be filled with operating water. The filling is completed quickly by a short opening of the solenoid valve. When the chamber is filled and pre ssurized the paring chamber will start to fill. 36. Which has the greater pressure in a stern tube sealing seawater or L.O. Ans. L.O. has the greater pressure 37. What is the purpose of turning gear Ans. Turn the flywheel during preheating prior to departure or during the maintenance of the engine which require positioning of the piston. 38. Locate nozzle in a turbocharger Ans. Nozzle of turbocharger can be located on the gas side directed towards the blades of the turbine. 39. What is the function of mouth ring Ans. The mouth ring is installed in the pump to prevent the pump from axial movement. To prevent the contact of casing with the impeller so as to avoid wear between the two surface wear ring is also installed Japanese Licensure Examination 44
    • 40. What is flash point Ans. The lowest temperature at w hich fuel will evolve a flammable vapor that will 41. ignite. In the presence of flame. How do you check steering gear Ans. The test procedure to be carried out not more than 12 hours before departure (or weekly on short -voyage vessels) requires operation gear, of (where auxiliary position, gear, emergency applicable) remote power the control supply, following: systems, rudder main steering bridge steering indicator, power failure alarms for remote control systems and also for the steering gear power unit. While the gear is running, full movement must be checked and a complete visual inspection must be carried out. The phone or other means of communication between bridge and steering compartment must be tested also. While the ship is at sea with the automatic pilot in prolonged use, manual steering must be tested before entering busy or restricted waters. When in such waters both power units (pumps and motors) must be running if simultaneous operation is possible. At three-monthly control and intervals emergency communication; and drills operation (in cluding with local alternative pow er) should be carried out . All officers are required t o be familiar with the steering gear and the changeover arrangements. Instructions for changeover must be displayed in the steering compartment and on the bridge. The various tests and checks should be logged. 42. What is pitch Ans The distance in meter traveled by the propeller in one revolution if it works in a solid an unyielding medium 43. What is the cause of pressure drop in a cen trifugal pump Ans. ~ Loss of suction Japanese Licensure Examination 45
    • ~ Impeller damage 44. Identify the parts of propeller 45. Explain adiabatic expansion Japanese Licensure Examination 46
    • Ans. A process involving no change in energy during expansion 46. . What is entropy Ans. The measured quantity of disorderliness 47. . What is the common source of leak in stern tube Ans. Stern tube seal aft side 48. What is the purpose of bilge separator Ans. An equipment that separate the oil content in the bilge t o the quantit y allow ed by M ARPOL 49. Reason why we should avoid low speed running on diesel generator? Ans. ~ Carbon build up in the engine/prime mover ~ Low frequency 50. What will you check if one cylinder of your engine is not like others? Ans. ~ Exhaust temperature ~ Jacket cooling water outlet temperature ~ Fuel pump rack scale ~ Fuel injection timing ~ Fuel injector atomization and opening pressure ~ Check Pmax and Pcom Japanese Licensure Examination 47
    • 51. What is the purpose of gravity disc in centrifugal purifier? Ans. For purifier operation, the interface for s eparating light liquid and heavy liquid in the bowl must be held to within the certain range. Gravity discs of different inner diameters are used to change liquid outlet diameter, thereby controlling the interface position. 52. Causes of F.O Purifier abnormal flow? Ans. ~ Inappropriate selection of gravity disc ~ Incorrect oil treating temperature ~ lack of sealing water/Interval too short ~ Scale formation on operating water device ~ Defective o-rings, main seal ring and inop erative pilot valve ~ Bowl not closed ~ Dirty operating water strainer ~ Too much sludge deposition on disc plates 53. What type of pump use in boiler --F.O system? Ans. Gear pump 54. Give the function of evaporator? Ans. ~ A place were the refrigerant boils and changes it states ~ Absorbs heat in the space being cooled 55. What are the causes of L.O. high temperature? Ans. ~ Fouled cooler Japanese Licensure Examination 48
    • ~ Hunting of control valve ~ Insufficient cooling water volume ~ Overloading 56. How to detect starting valve leaks? Ans. ~ Feel over method, by touching the starting air inlet pipe 57. What are the causes of dirty lubricating oil? Ans. ~ Prolong blow by ~ Centrifuge not working properly ~ Too much carbon in suspension ~ Dilution of fuel 011 ~ Ineffective sealing on stuffing box (worn out) 58. What is the purpose of spiral gear in a purifier? Ans. ~ It transmit the power from the motor to the ve rtical shaft ~ Increase up the speed of the vertical shaft pinion gear 59. How much pressure on air reservoir? Ans. ~ 25 bar ~ 30 bar 60. What is non-destructive test and what is the purpose of it? Ans. Non-destructive test are c arried out on components, not test pieces. They are use to detect flaws or imperfections during manufacture or those that develop during service. The test give no indication of mechanical properties. Visual inspection of surface defects is assisted by penetrant or magnetic crack detection to find the presence and Japanese Licensure Examination 49
    • full extent of hairline cracks. When internal flaws are suspected, use is made of x-rays or ultrasonic testing. There are special devices for examination of machine finish. ~ Liquid penetrant methods One type of test uses a low viscosity liquid, containing a fluorescent dye. The area to be tested is sprayed or soaked and .@fter time lapsed, to allow for penetration by capillary action, is wiped dry'. When viewed under the ultra violet light, any fau lts will be shown up by the glow of the penetrant in t hem. Anot her t est uses a penet rant containing as powerful dye. This is sprayed on the suspect area with an aerosol. Aft er aloowinng time for penet ration, this area is wipe clean and covered with a liquid which dries to leave the chalky sediment. The penetrant stains the developer along the line of the crack. ~ Magnetic crack detection This type of test is suitable only for materials, which can be magnetized. Aft er the test , the component is normally de -magnetized. A magnetic field electric current is produced in the component by means of an or permanent magnet particles are spread on the surface. Crarks are revealed by a line of magnetic particles. ~ Radiographic inspection X-rays and gamma rays are used for inspections of welds, castings, forging. Faults in the metal affect the intensity of rays passing through the material. Film exposed by the rays gives a shadow photograph when develop. ~ Ultra sonic testing Internal flaw detection by ultrasonic me ans is in principle similar to radar. The reflected probe back by emits high any flaws frequency in the sound object. waves which Reflections are were also received back from the opposite surface. The probe is connected to a cathode ray oscilloscope, which shows the result in a simple way. 61. Where can you find feed check valve and feed stop valve and give the purpose of it. Japanese Licensure Examination 50
    • Ans. ~ Feed stop valve A mounting valve fitted on the water drum intended to isolate the feed line from the boiler in any even t of maintenance. ~ Feed check valve A valve on a boiler in conjunction with the feed stop valve to prevent back pressure on the feed line. 62. What are the causes of troubles in a boiler during operations? Ans. ~ Water on fuel ~ Dirty atomizer assembly ~ Low fuel oil temperature ~ Dirty flame eye ~ Clogged strainer 63. What are the causes of positive and negative propeller slip? Ans. ~ Weather condition ~ Wind force direction ~ Direction of current ~ Condition of hull 64. What is the pressure of fuel oil on main engine and diesel generator? Ans. Before and Aft er injection pump ~ Main engine 8.0- 9.0 to 320 bar ~ Diesel generator 8.0- 9.0 to 180 bar 65. Preparation before arriving port Japanese Licensure Examination 51
    • Ans. ~ Start additional generator and put on parallel ~ Prepare boiler ~ 12 hours before test steering gear ~ Main engine test ahead and astern ~ Powered by hydraulic line with coling ~ Prepared mooring lines 66. Where is the expansion tank located? Ans. At the top most portion of the engine room 67. How the F.C.W. system of diesel engine circulate? Ans. The cooling water system is divided into two lines, the jacket line and the cooler line. The standard cooling medium used for jacket line is fresh water and that for the cooler line is sea water. The temperature control valve controls the jacket cooling outlet temperature by passing the fresh water cooler. 68. What are the procedures on how to anneal? Ans. This is usually accomplished by heating the material to slightly above the of the critical temperature. holding it there until the temperature piece is uniform throughout. and then cooling at a slowly controlled rate so that the temperature of the surface and that of the center of the piece are approximately the same. 69. How many percent (%) of carbon content in a Cast Iron? Ans. Cast Iron ~ 2.0% ~ 3%-5% - gray cast iron Carbon steel ~ low carbon -less than .30% Japanese Licensure Examination 52
    • ~ medium carbon - .30% to .700/0 ~ high carbon - .70 to 2.0% (normally the upper limit is 1.40%) 70. What will happen if the centrifugal pump has no pressure? Ans. ~ The pump tends to overheat and vibrate 71. What are the things to do when approaching the port? Ans. ~ 12 hours before test steering gear ~ start another generator for power reserved ~ stand by boiler ~ reduce rpm until harbor speed ~ stand by engine ~ test main engine ahead and astern 72. Give the safety precaution when working in a high place. Ans. ~ Secured permit for working aloft ~ Tool box meeting ~ Prepare tools and secured in a container ~ Use personal protective equipment ~ Secure harness before doing something ~ Focus on the job 73. Checking points in steering gear system? Ans. ~ Hydraulic oil working tanks ~ Motor amperage ~ Leaks of hydraulic oil ~ Ram cylinders ~ Hydraulic valves Japanese Licensure Examination 53
    • 74. What are the procedures in paralleling DIG? Ans. ~ Start generator and check if nonnal ~ Check frequency and voltage ~ Switch synchroscope ~ Watch for the direction of pointer fast or slow ~ Adjust frequency through governor control switc h, balancing the frequency ~ Close ACB ~ Balance the load if both on IFO through governor control switch 75. What is the indication of leaking starting valve of an engine? Ans. ~ Increased in temperature of starting air pipe 76. What will be the cause of high temperature in one cylinder of DIE? Ans. ~ Defective fuel oil injector ~ More volume of fuel/rack adjustments ~ Injection timing ~ Leaky exhaust valve 77. What is the purpose of air cooler of DIE? Ans. ~ To reduce temperature of scavenge air but above dew point and increase the density of scavenge air. Japanese Licensure Examination 54
    • Second Assistant Engineer (2AE) STEAM PLANT 1. What are good characteristics of good combustion in a boiler? Ans. Proper amount of oil (sufficient pressure) Proper amount of air Proper atomization (good mixture of oil and air) Proper oil temperature 2. What do you analyze from boiler water analysis? Ans. Chloride Content , Alkalinit y, hydrazine, pH -value, conductivit y 3. What do you treat in high alkalinity of boiler water? Ans . Blow Down and Chemical treatment 4. What is a feed water pump? Dearator feed heater? Ans. Feed Water Pump is the one which forces the water to enter into the boiler. Deaerator Feed Heater is the one that s ufficiently preheats the feed water to minimize oxygen 5. before entering the boiler. What is the purpose of the nozzle of impulse turbine? Ans. Japanese Licensure Examination 55
    • Nozzle is fitted in impulse turbine to change thermal energy into velocit y. Also t o direct jet of st eam from no zzles against blades mounted on a wheel which is converted into work. 6. What are the things needed to have an efficient boiler burning? Ans.   Proper amount of air  Proper atomization (good mixture of oil and air )  7. Coorect amount of oil (sufficient pressure) Proper oil temperature Name Of Parts And Each Purpose Ans. 1. CONDENSER – where the exhaust steam of main and auxiliaries are put into. By means of cooling medium like seawater, the steam condenses and converted into water. 2. 8. FEED PUMP – forces the feed water into the boiler. What are the causes of emergency stop in a steam engine? Ans. - overspeed, - low lub.oil pressure and back pressure. - 9. What is the normal vacuum pressure in a steam turbine atmospheric condenser? What would cause the press to fa ll? Ans. - Vacuum is 760mmHg (720mmHg and above is considerable) - Air leaks into the condenser due t o poorly functioning low pressure steam seals or to a leak at the connection between turbine and condenser. - Air ejector may not be operating proper ly. Japanese Licensure Examination 56
    • - Insufficient cooling water. Steam side of the condenser may be fouled, the waterside may be coated with mud, or the division plate in the two-pass condenser may be cracked. 10. Steam turbine (function and parts) 1. Economizer - use to heat feedwater before entering the steam drum utilizing the heat from exhaust gas 2. 2nd dearator - remove oxygen and heat feedwater 3. Gland steam seal - prevents steam form high pressure side of turbine from escaping and prevents air from entering the low pressure side 4. 1st feed heater - increase the temperature of the condensate 5. Condenser - exhaust steam is converted into condensate 6. Main feed pump - supply feedwater at high pressure to the boiler 11. What is the boiling point of water? Ans. 1000C at atmospheric pressure 12. What are the safety devices of boiler? Ans.  Fuel oil cut-off for low low boiler water level  Fuel oil cut-of for miss-fire (flame eye system)  Fuel oil cut -off at F.D. fan stop and Low press. At omizing steam   Low control air pressure and Low F.O. pressure  Low Low boiler water level trip  13. Fuel oil cut-off at Control room or Boiler gauge Board Safety valve for excess steam pressure What is the effect of high alkaline water to a boiler? Ans. Japanese Licensure Examination 57
    • Scale and caustic embrittlement. 14. Steps in starting boilers. Ans. The uptakes should be checked to ensure a clear path for the exhaust gases through the boiler; any dampers should be operated and then correctly positioned. All vents, alarm wat er and pressure gauge connections should be opened. The superheater circulating v alves or drains should be opened to ensure a flow of steam through the superheater. The other entire boiler drains and blow down valves should be checked to ensure that they are not closed. The boiler should then be filled to slightly below the working lev el with hot de-aerating water. The various header vents should be closed as water is seen to flow from them. The economizer should be checked to ensure that it is full of water and all air vented off. The operation of the forced draught fan should be check ed and where exhaust gas air heaters are fitted they be by passed. The fuel oil system should be checked for the correct positioning of the valves, etc. The fuel oil should then be circulated and heated. 15. Small gear found in the steam turbine. Ans. Pinion gears are used in steam turbine for the purpose of speed reduction. 16. What is an Economizer? Ans. The auxiliary steam installation or economizer provided in a modern diesel powered tankers usually uses an exhaust gas heat exchanger at the base of the funnel and one or perhaps to water tube boiler. Saturated or superheated steam may be obtained from the auxiliary boiler. At sea it act s as st eam receiver or for the exhaust gas heat exchanger which is circulated through it. In port it is oil fired in the usual way. Japanese Licensure Examination 58
    • 17. What are the methods of heat transfer? Ans. There are three methods of heat transfer, by conduction, convection and radiation. - Conduction – heat is transferred through solid body. - Radiation – transfer of heat from a source across an intervening space no material or subject. - Convection – transfer of heat through the motion of the heated matter that is through the motion of the heated smoke, hot gases and air. 18. Types of pressures Ans. At mospheric pressure – t he normal; pressure at open atmosphere which is equal to 14.7 psi or 1 bar Gauge pressure - actual pressure that can be read at most common pressure gauges. Absolute pressure - the sum of gauge pressure and atmospheric pressure. 19. What are the different parts of impulse reaction turbine? Ans. 1. 2. Casing 3. Impulse and reaction moving blades. 4. Metallic labyrinth packing 5. Steam nozzle 6. Water seal 7. Turbine shaft 8. 20. . Stationary blades Dummy piston What is the color of the flame of the boiler ru nning in good condition? Japanese Licensure Examination 59
    • Ans. Gold color flame 21. What type of pump is a commonly used in auxiliary boiler? Ans. Multi stage Centrifugal pumps 22. What is the specific heat of water? Ans. 1 kcal/kg 23. What do you do to prevent flareback? Ans. 1. 2. Well maintained atomizer/nozzle 3. 24. Alw ays clear furnace of foul gases before lighting off. Never allow firemen to light off fires from hot brickwork. What is a brake horsepower? Ans. The power developed by an engine as measured by the force applied to a friction brake or by an absorption dynamometer applied to the shaft or flywheel. 25. What is the purpose of a de-superheater? Ans. De-superheater acts to lower the temperature of a superheated steam with its temperature just equal or greater than satur ated steam used for auxiliaries. 26. What is the purpose of corrugated furnaces? Ans. Japanese Licensure Examination 60
    • 1. The corrugation permits a bellow -like action, and so allows expansion to take place with no strain being imposed on either the boiler front or the combustion chamber. 2. The corrugation offers an enlarged area and so increases total heat transfer from the furnace to the surrounding. 3. The corrugations serve as stiffeners, which reinforce the furnace. 27. What are the causes of steam turbine failure? Ans. 1. 2. Improper flow to the condenser. 3. Air leaks int o the condenser. 4. Air ejector may not be operating properly. 5. Condensate pump speed my be slow. 6. Priming or water carry over 7. Abnormal vibration 8. 28. Insufficient circulating water. Insufficient lubrication What is the purpose of superheater? Ans. It receives steam from the dry pipe and this steam, being superheated by combustion gases passing around the outside of the tubes, is increased in temperature, although the pressure stays practically the same. 29. Given a cutaway isometric view of the steam turbine] Examinee was asked to identify the following parts: Ans. a. Condenser b. First reduction gear pinion c. High pressure d. Pinion gear Japanese Licensure Examination 61
    • 30. What is thrust bearing? Ans. Avoid contact of blade and casing by preventing axial movement 31. Give five boiler mounting valves. Ans.   Main Steam Stop valve  Feed Check Valve  Blow Down valve  32. Safety valves Auxiliary Steam Stop Valve. In steam boiler, what are the various test in water boiler? Ans. Chloride Test , Alkalinit y Test , pH -value, hydrazine conductiv it y, hardness, phosphate. 33. How much calorific value of heat is needed to heat 0 c of -100C 00C 00C +100C Ice Ice H2O H2O HEAT 34. HEAT HEAT What will happen if boiler backfires? Ans. Accident to human occurs especially when it was not lit prope rly. Shortens the lifespan of brickwork. 35. What is the color of flame if the boiler is running in good condition? How about when it is not in good condition? Ans. Japanese Licensure Examination 62
    •  A yellowish orange, rolling flame indicates good combustion.  An incandescent whit e flam e with jagged edges indicat es excess air. 36. How does the steam work in a steam turbine? Ans. A high velocity jet of superheated steam is directly to the nozzles in impulse turbine or by stationary blades in reaction turbine against the blade row to prov ide rotational motion of the shaft which is connected to the of reduce reduction gear leading to propeller. 37. What are prevent it causes boiler backfire and steps in how to from happening? Ans. Too much accumulation of unburned fuel and unpurged g ases in the furnace resulting from inefficient combustion caused by the following: too low or too high fuel oil temperature (should be maintained at proper temperature), insufficient air -fuel ratio (should be properly adjusted considering the observed flam e) prepurging not done before flashing (should always be the first step to do before flashing up the boiler to emit the accumulated gases inside the furnace), dirty burners and swirler (should be cleaned up 38. and check for proper atomization). What are the causes of high alkalinity in boiler water? Ans. Presence of scale 39. What are sensible heat, latent heat, and specific heat of water? Ans. - Sensible heat – is the heat that is added to or taken away from a substance which will cause an increase o r decrease of temperature as recorded by a thermometer, but will not cause a change of state. By change of state is meant the change of a solid to liquid, a liquid to a gas, or vice versa. - Latent heat - is the heat that is added to or taken away from a substance without Japanese Licensure Examination an increase or decrease of 63
    • temperature. It does, however, cause a physical change in the state of the substance such as a change from solid to liquid, liquid to a gas, or vice versa. - Specific heat is the ratio of the amount of heat, or the number of heat units required raising the temperature of a substance one-degree to the amount of heat required raising the temperature of an equal weight of water one degree. 40. What are the causes of turbine vibration Ans. - 41. Insufficient warming -up procedure Improper clearances Identify the parts of steam turbine Ans. 42. What is the normal Ph value of boiler water Ans. 10.5 Japanese Licensure Examination 64
    • 43. Causes of the dilution of lubricating oil in a team turbine? Ans. ~ To much steam pressure on gland sea ling steam ~ Leaking tube bundle of lubricating oil cooler. 44. Explain briefly - good combustion of auxiliary boiler? Ans. However, furnace of Complete a the achievement boiler requires combustion can be of good practical combustion knowledge obtained there is and within the experience. sufficient time (a function of furnace volume), turbulence (provided by the geometry of the burner assembly), and a temperature high enough to provide ignition. Some aspects are to be observed: ~ Quality of fuel being burn ~ Temperature of fuel ~ Air/fuel ratio or excess air ~ Condition of oil burners ~ Furnace pressure ~ Wind box pressure Such this factors are observed and frequent checking of stack gas for analysis if ever their need to increase air or fuel oil p ressure. 45. Method of testing or checking boiler water? Ans. Test procedure: CONDENSATE PH TEST ~ Collect 50 ml of condensate sample and pour into dish ~ Add t hree drops of phenolphthalein. Sample should t urn pink. ~ Add sulfuric acid N/10 drop by drop until pink color disappears ~ Refer to chart for dosage adjustment AMERZINE Japanese Licensure Examination 65
    • ~ Collect 25 ml of cooled condens"ate ~ Use Amerzine ampoule refill and break the tip ~ Agit ate for 10 min. for best result ~ Compare color for dosage adjustment EXCESS PHOSPHATE TEST ~ Collect and filter cooled boiler water to 5ml mark on phosphate test tube ~ Add molybdate to 17.5 ml mark ~ Add one brass spoonful of dry stannous chloride ~ Put cork stopper and agitate the solution to stand 3 to 5 mln ~ Compare color with standards in block ~ Refer to chart for dosage adjustment PHENOLPHTHALEIN (P) ALKALINITY TEST ~ Collect 50 ml of cooled boiler water sample and pour into dish ~ Add 4 drops of phenolphthalein, sample t urns pink ~ Pink color alkaline, no color P alkalinity zero ~ Add sulfuric acid N/10 until pink color disappears ~ Note the level of acid in buret convert ml to ppm using the chart and record results in ppm ~ Keep sample for T alkalinity test, refer to chart for dosage adjustment TOTAL (T) ALKALINITY TEST ~ Add 3 drops of total alkalinity indicator ~ Add sulfuric acid N/10 until pink color develops ~ Note the level of acid in buret ~ Total alkalinity results must less than twice the P alkalinity CHLORIDE TEST ~ Add 10 ml of cooled boiler water into vial ~ Add 3 drops of phenolphthalein until pink color develops Japanese Licensure Examination 66
    • ~ Add sulfuric acid N/10 drop by drop until pink color disappear and add one more drop ~ Add 6 drops of potassium chromate, sample t urn to yellow ~ Add Silver Nitrat e drop by drop and record t he number of drops ~ Note: 1 drop of silver nitrate equal to 10ppm CONDUCTIVITY TEST ~ See meter instruction ~ Fill the cylinder to 100 ml top mark with cooled boiler sample ~ Add 2 drops of phenolphthalein and mix ~ Add gallic acid to pink sample, while mixing, u ntil color disappears ~ Measure temperature of sample and adjust temperature dial ~ Rotate conductivity dial until both lights remain lighted at the same time ~ Refer to chart to adjust blow down. 46. What is mean carryover of Aux. Boiler? Ans. Consist of particles of leaving the boiler with steam cause by high alkalinity, high dissolved suspended solid and high chloride content. 47. What are steam turbine parts usually come into damage? Ans. ~ Rotor ~ Blades ~ Labyrinth gland ~ Bearings . ~ Nozzle ring ~ Diaphragm Japanese Licensure Examination 67
    • 48. Why must we pay attention when we drain steam in steam turbine. What factors are observed? Ans. In draining the turbine, steam warming by -pass valve should be open gradually to avoid hammering and dr ain valve keep open all the time. ~ Thermal shock must be avoided all the time ~ Procedure/checklist should be observed during warming operation with regards to makers recommended procedure ~ Check all parameters ~ Lubricating oil should be supplied 49. What type of pump use in boiler F.O system? Ans. Gear pump 50. What parameters to be reported when we send lubricating oil for shore analysis? Ans. ~ Lubricating oil running hours ~ Viscosity ~ Sampling point or origin of oil ~ Type or grade of oil 51. In boiler, what does steam and smoke goes out to the funnel. What reasons? Ans. ~ Tube failure ~ Leaky safety valves or incorrect popping setting Japanese Licensure Examination 68
    • 52. Where can you find the feed check valve and feed stop valve and give the purpose of it? Ans. ~ Feed stop valve A mounting valve fitted on the water drum intended to isolate the feed line from the boiler in any event of maintenance. ~ Feed check valve A valve fitted on a boiler in conjunctio n with the feed stop valve to prevent back pressure on the feed line. 53. What are the causes of troubles in a boiler during operations? Ans. ~ Water on fuel ~ Dirty atomizer assembly ~ Low fuel oil temperature ~ Dirty flame eye ~ Clogged strainer 54. Give the purpose of nozzle in impulse turbine? Ans. ~ Serves to convert the high pressure and high energy of the steam into a high velocity jet of steam with a reduce pressure and energy content. 55. What is gland sealing steam? Ans. ~ Steam is prevented from leaking out of the rotor high pressure end and air is prevented entering the low pressure end. 56. How to prevent back fire of boiler? Ans. Japanese Licensure Examination 69
    • ~ Furnace purge ~ Check leaky fuel valves to t he burner 57. What is the used of economizer in boiler? Ans. ~ Feed water pre-heater ~ Produce steam during underway 58. What is the Seal packing gland for turbine? Ans. ~ Steam is prevented from leaking out of the high pressure en d and air is prevented from entering the low pressure end by the use of glands 59. What is the flow of steam in an impulse turbine? Ans. ~ The high velocity steam is directed on the blades fitted around the turbine wheels, the blades being of cur ved section so that the direction of the steam is changed thereby imparting a force to the blades to push the wheel around. 60. What will happen if you blow the soot in the boiler? Ans. ~ Increase in efficiency ~ More steam is produce ~ Avoid t ubes overheating 61. State the purpose of air heater? Ans. To heat-up the draft air before entering the furnace by recovering the heat of the exhaust gas 62. How to operate soot blower of boiler and economizer? Ans. Japanese Licensure Examination 70
    • ~ Raise up steam as high as possible ~ Drain the steam line until free of condensate ~ For boiler start force draft fan ~ Increase draft air pressure ~ Open steam valve and start soot blow on several direction 63. What do you mean by A.C. C.? Ans. Aut omatic combustion control 64. What is the thermal efficiency of a diesel engine? Ans. The thermal efficiency of an engine is the relationship between the quantity of heat energy converted into work and the quantity of heat energy supplied Thermal Efficiency = Heat energy converted into work Heat energy supplied 65. What is a blow down valves? Ans. A boiler mounting valve fitted on the bottom of the water drum use to empty or control the degree of contaminatio n in a boiler. Second Assistant Engineer (2AE) REFRIGERATION Japanese Licensure Examination 71
    • 9. What are the three methods of heat transfer? Give example for each Ans. 1. 2. Convection – liquid flow (circulation) 3. 10. Conduction – transfer of heat from metal to metal Radiation – heat from sun rays Name the four most important components of a Freon refrigeration system. Ans. 1. 2. evaporator 3. condenser 4. 11. compressor expansion valve What is an expansion valve and its purpose? Ans. An expansion valve is the one that regulates the flow of refrigerant entering the evaporator. 12. What happen when the expansion valve is excessively open? Ans. Flooding of refrigerant in the evaporator takes place, back pressure would rise and frost would form on the cylinders. 13. Kind of refrigerant use in a refrigerating system Ans. Boiling temp. R-22 at atmospheric – 410C Boiling temp. R-12 at atmospheric – 300C Boiling t emp. Amm onia at atmospheric – 160C 7. What are the characteristics of Freon 12? Ans. Japanese Licensure Examination 72
    • Colorless, odorless, non -irritating, non-flammable, non-poisonous, non-explosive, an excellent solvent, non -corrosive to metals ordinarily used in refrigerating units. 8. Purpose of condenser in refrigeration system. Ans. Absorbs the high press. And high temperat ure refrigerant gases from the compressor and converts its sta te in liquefied form with the aid of cooling water. 9. Kinds of refrigerants and their properties. Ans. Freon 12 (CCl2F2) a) Colorless, odorless b) Non-flammable, non-poisonous c) Non-irritating, non-poisonous d) Non-corrosive to metal, excellent solvent e) Boiling point – 21.60F @ atmospheric pressure f) Alw ays available in t he market g) Low power consumption @ higher efficiency h) Soluble when mixed with oil @ lower viscosity and pour point. Ammonia (NH3) a) Colorless, corrosive b) Pungent odor c) Very soluble in water d) Boiling point @ atmospheric pressure – 280F e) Combustible or explosive when mixed with air f) Health hazard due to exposure affect lung tissues g) Solubility is fairly low when mixed with air h) Require high power consumption which gas needed to condense Carbon Dioxide (CO2) a) High specific gravity Japanese Licensure Examination 73
    • b) c) Non corrosive, non poisonous d) Non explosive and very safe to health e) 10. Colorless, odorless Boiling point @ atmospheric pressure – 109.30F What will happen if there is moisture in refrigeration system? Ans. There will be a decrease in heat tran sfer, thereby not achieving the desired low temperature. One instance is the expansion valve is frosting causing ice, which then acts as an insulator. 11. Explain the cycle of refrigeration system. Ans. Four major parts involved – compressor, condenser, expa nsion valve and evaporator. The system is composed of two sides, the high and low-pressure sides. High-pressure side components: From compressor pressure outlet side to the inlet components: From of the outlet expansion of valve. expansion Low valve to compressor inlet. 12. Give the different ways of detecting leaking refrigerant? Ans. 1. A soapy lather spread over joint or pipes will bubbles at the leak. 2. Dampen a piece of litmus paper and run it along piping joint s, valve stems, et c. An ammonia leak will t urn t he litmus paper blue. 3. A sulfur stick passed along the piping, etc will give off a dense white smoke on coming in contact with a leak. 4. Leaks in the condenser may be detected by applying litmus paper in circulating water discharge. The litmus paper turning blue will indicate a leak. 5. For freon, by the use of halide torch. Its normal blue flame will turn green in the presence of freon 13. What is the cold side of the refrigeration system? Japanese Licensure Examination 74
    • Ans. The cold side of the refrigeration system is the evaporator. The refrigerant entering the evaporator at a temperature lowers than the secondary coolant receives latent heat and evaporates. Later this heat is given up in the condenser when the refrigerant is again liquefied. In larger installations the evaporator cools air or brine. These are circulated in turn a secondary refrigerants. 14. What is the purpose of liquid receiver? Ans. The liquid receiver refrigerant in the is fitted system to to give cater a sufficient for various reserve of operating conditions. Secondly, for storage of the refrigerant where it is required to pump over, i.e., store the charge for maintenance purpose. 15. What are specific heat, latent heat and sensible heat? Ans. Specific heat – is the ratio of thee amount of heat required to raise a mass of a material, 1 degree in temp. to the amount of heat required to raise an equal mass of a reference substance, usually water. Latent heat – is the amount heat absorbed or evolved by one mole, or a unit mass of a substance during a change of stat e at constant temperature and pressure. Sensible heat – the quantity of heat required to change the temperature of a substance but does not change of the substance. 16. Where is the warm side of a refrigeration system? Ans. Condenser 17. What would happen if there was water in refrigeration line? Ans. Japanese Licensure Examination 75
    • Water circulating with Freon tends to freeze on the regulator causing a build up of pressure on the evaporator side due to blockage. The machine tends to stop by the high pressure cut out. 18. What safety device will activate to stop the compressor in the refrigeration system? Ans. Solenoid valve 19. What phenomenon becomes when air mixed with refrigerant? a. Delivery pressure increase b. Outlet gas temperature Ans. a.) ~ High discharge gauge reading ~ Jumping of gauge pointers ~ Inefficient working b.) ~ High cooling outlet temperature of condenser ~ High refrigerant temperature 20. What is the effect if your refrigeration system has an air? Ans. This is indicated by an abnormally high refrigerating compressor head pressure readings and possibly by the presence of small bubbles in the sight glass 21. What is short cycling in refrigeration system? Ans. Condenser coolant restriction causing high pressure d ischarge cut outs, choked expansion valve giving low pressure 22. What is the hottest part of refrigerant in the refrigeration system? Ans. Japanese Licensure Examination 76
    • The high pressure side from which the refrigerant is discharged. 23. Diagram of refrigeration Ans. ~ Compressor ~ Condenser ~ Liquid receiver ~ Expansion valve ~ Evaporator coil 24. Give the function of evaporator? Ans. ~ A place were the refrigerant boils and changes it states ~ Absorbs heat in the space b eing cooled 25. What is a magnetic valve of refrigeration system? Ans. ~ Solenoid valve 26. In refrigeration, why during operations is running low pressure at the suction side? Ans. The expansion valve tends to control the degree o f superheat in the evaporator, were the refrigerant boils and absorbs heat in a lower pressure. 27. What is a liquid flooding in refrigeration system? Ans. Liquid refrigerant enters the suction sude of the compressor 28. What are the safety device that are fitted in a refrigeration system? Ans. ~ Lubricating pressure switch Japanese Licensure Examination 77
    • ~ High pressure switch ~ Lubricating oil pressure switch 29. What is flaring tool? Ans. Used for tubing connections in enlarging the inside diameter of th e tube to a tapered shape. Second Assistant Engineer (2AE) ELECTROTECHNOLOGY 1, How are voltmeter and am meter connected in the circuit? Ans. Voltmeter - connected in parallel Ammeter - connected in series Japanese Licensure Examination 78
    • 2, What is the function of s pace heaters for motors? Ans. Maintains the temperature of motor windings to avoid the formation of moisture. 3. What is Ohm slaw? Ans. Ohm's law states that the current of a circuit is equal to the voltage divided by the resistance. Current or amperes is generally indicated by the letter I; pressure or voltage by the letter E; and resistance or ohms by the letter R. Thus, Ohm's law becomes; Amperes = volts/ohms or I = E/R The transposition of the formula to find volts and ohms would be: Volts = amps x oh ms or E = I x R Ohms = volts/amps or R = E/I 4. Enumerate the parts of Main Switchboard Ans. Synchronizer, meter circuit breaker Indicating lamps, synchroscope, earth lamps, interlocks. 5. Examples of good conductors of electricity. Ans. ~ Aluminum ~ copper ~ and silver 6. Examples of good insulators. Ans. - Porcelain - rubber - and mica Japanese Licensure Examination 79
    • 7. What are to be checked in an induction motor? Ans. Induction motor are checked for their insulation resistance and winding resistance. Insulation resista nce must not be lesser than 1 megaohm. Periodic cleaning and maintenance must be observed. Check on bearing and lamination must also be done. 8. How may a battery discharges? Ans. In discharging batteries, the hydrogen ions remove oxygen from the lead peroxide of the positive plates and combined with it to form water (H2O). Loss of oxygen from the lead peroxide reduces it to gray lead. The water formed by the action dilutes the electrolytes so that as the cell discharges, the specific gravity decreases. Measurements of the specific gravity change with a hydrometer will show the state of change of the cell. At t he negative side of t he cell, sulphat e ions (504) combine with the pure lead of the reg. Plates to form a layer of white lead sulphate. The lead sul phate layer increases during discharge and finally covers the active material of the plate so that further reaction Is stifled. Some sulphate also forms on the positive plates, but this Is not a direct part of the discharge action. 9. How to find ground in main switchboard? Ans. By using megger tester, conducting Insulation resistance and winding resistance. 10. What is the cause of motor not to start? Ans. 1. Loose connection 2. Wrong polarity for a D.C. motor 3. Burn-out motor 4. Tripped breaker Japanese Licensure Examination 80
    • 5. Burn-out fuse 11. Where can you find space heater lam p and what is its purpose? Ans. Space heater lamp can be found on MSB to indicate If space heater is running or not. 12. How do you detect earth by lam p? Ans. Push the earth lamp button. when the l ights on with the degree of illumination it indicates the circuit is not grounded. 13. Why the transformer is mostly used aboard the ship? Ans. Transformer is incorporated in battery charges, instrument connection on AC w ork. and pow er distribution syste ms. With their use voltage can be stepped up or down by a simple and efficient means without supplies can be change of frequency. Safety working improved with transformer step down and isolation from the switchboard. To reduce 440 volt s 3 -phase AC into 120 volts for general use. 14. Electrical Symbol 15. List the different devices and components of main switchboard. Japanese Licensure Examination 81
    • Ans. Interlock devices, circuit breaker, ground detecting system, preference trip device, electrical meters, Indicating lamps, a nd synchroscope. Relays, fuse, starting switches 16. What are to be checked in an induction motor? Ans. Induction motor are checked for their insulation resistance and winding resistance. Insulation resistance must not be lesser than 1 mega-ohm. Periodic cleaning and maintenance must be observed. Check on bearing and lamination must also be done. 17. How do you detect earth by lam p? Ans. Push the earth lamp button, when the lights on, it indicates the degree of illumination of the circuit which not ear thed. 18. How do you reset the circuit breaker? Ans. In case of a trip, rectify first the fault. Then just press the "reset" button. 19. What is the purpose of ventilation in the battery room? Ans. To prevent the emission of toxic gases which is detrim ental to heath. 20. What are the usual checks when induction motor is running? Ans. ~ current ~ abnormal sound ~ temperature rise ~ vibration 21. Methods to dry up wet induction motors Japanese Licensure Examination 82
    • Ans. ~ It frequently becomes nece ssary to dry out electrical machinery eitther because it has been exposed to the weather before commissioning or because it has been accidentally immersed. In the latter case, if the immersion is in the sea water, all salts deposits should first be washed out with plain water. ~ In many cases it may also advisable to dismantle and rebuild the commutator as water deposited inside the commutator cannot be removed by drying processes. ~ either internal or external heating maybe applied, the machine should be enclosed or covered up to retain the heat, but in such a manner that moisture can escape either continuously or by periodically lifting the covers. ~ Use of electric heaters are most suitable, taking care that the hottest part of the machine does not exce ed 90 centigrade. 22. The unit of resistance Ans. Ohms 23. The lowest allowable insulation resistance Ans. 0.2 mega Ohms 24. What is space heater? Ans. An elect ric coil use t o prevent the condensation of moist ure when the machine is out of operation 25. What is hertz in electrical system? Ans. ~ The number of cycles the current passes through in one second ~ Unit of frequency Japanese Licensure Examination 83
    • 26. In electricity, what is commutator? Carbon brush? Ans. Commutator- This is compose of copper segments, insulated from each other by mica. The width of the top of a segment may be up to 6mm and the segments maybe mounted on but insulated from a sleeve, which is secured to the shaft, and are clamp by an end ring which can be bolted or screwed. Carbon brush - Any one brush is pressed ont o the commutat or by means of a pressure arm and is connected to a holder by means of a pigtail of braided wire which is moulded into the brush. One or more brush holders maybe carried on in insulated spindle which is mounted on the brush rocker ring. Brushes of modern d.c. machines are always of moulded carbon and graphite, the grade of hardness being chosen to suit the running conditions. 27. Draw a parallel circuit with one battery and two resistors . Derive the formula for resistance. Ans. 1/RT= 1/R1+ 1/R2+… 28. Define earth lamp? Ans. The earth lamp make it possible to examine the display lamps if the circuit is earthed or not, by manipulating the push button switch. The circuit, the volt age earth will apply to each of the three lamps so that the lamp for each will be applied to each brightness, which is lower than that of the display lamps. 29. What is the use of multi -tester? Ans. ~ Measure resistance ~ Measure voltage AC-DC ~ Measures amperage ~ Measures capacitance 30. How to check the diode, fuse and bearer switch? Japanese Licensure Examination 84
    • Ans. Continuity check 31. What is the formula to determine the speed of induction motor? Ans. Speed= Frequency (120) Number of poles Japanese Licensure Examination 85