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Cavitation erosion in the cooling water system of a diesel engine usually occurs at the pump impeller, and on the waterside of the ()
A . fuel nozzle holders
B . exhaust value guides
C . engine cylinder liners
D . low temperature and a low viscosity
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() is sometimes used for piston cooling since leaks into the crankcase would not cause problems.
A . Diesel oil
B . Hydraulic oil
C . Lube oil
D . Mineral oil
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Which of the following statements is correct for the design and installation of diesel engine cooling water systems?()
A . An alarm device with audible and visible signals is required for all cooling water systems
B . Propulsion engines with bores over 200 mm are to be fitted with cooling water jackets
C . Each totally enclosed cooling system shall be provided with a suitable head tank
D . Drain cocks are to be provided at the lowest points of all cylinder water jacket
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In a medium speed diesel engine, a trunk type piston may be cooled by() Ⅰ.oil circulation though passages in the piston crown Ⅱ.heat transfer through piston rings and liner wall
A . Ⅰ only
B . Ⅱ only
C . either Ⅰ or Ⅱ
D . neither Ⅰ or Ⅱ
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In a refrigeration system, if the cooling water to the condenser fails, the().
A . box temperature solenoid valve will close
B . expansion valve will close
C . compressor will shutdown
D . king valve will ope
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In a closed cooling water system, which of the problems can cause the water pressure to fluctuate?()
A . An open vent in the cooling system
B . A fouled sea chest
C . A restricted water passage in the engine
D . Air entrained in the cooling water
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Large marine diesel engines of crosshead construction generally have two systems of lubrication: a total loss system feeding the () and a recirculation system lubricating the running gear and cooling the piston.
A . cylinder liners and piston rings
B . main bearings
C . crankpin bearings
D . turboblower
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The compressor in an air-cooled condensing refrigeration system is short cycling on the high pressure cutout switch()
A . system is overcharged with refrigerant
B . system is low on refrigerant
C . discharge valves are leaking excessively
D . discharge valves are leaking slightly
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The main distribution duct in an air conditioning system which contains the cooling coils and filters is called the()
A . manifold
B . condenser
C . chamber
D . plenum
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()diesel engines generally have two systems of lubrication:()a total loss system feeding and a circulating system lubricating the running gear and cooling the pistons.
A . Large crosshead type;crossheads
B . High speed;the cylinders
C . Large crosshead type;the cylinders
D . Four-stroke;pistons and cylinder
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IBM System x and BladeCenter systems use cooling technology that allows managed airflow to each component. What is the name of this technology?()
A . Calibrated Vectored Cooling
B . Rear Door Heat eXchanger
C . IBM Active Energy Manager
D . Light Path Diagnostic
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Around the combustion chamber, all the main components are bore cooled to give low strains and the smallest, circumferentially symmetric deformations for good sealing between piston rings and liner()
A . thermal
B . mechanical
C . plastic
D . elastic
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() allows for expansion and water make up in the water cooling system.
A . A top tank
B . A head tank
C . A head valve
D . A drain tank
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The jacket water temperature in a diesel engine closed freshwater cooling system is normally controlled by ()
A . regulating the level of corrosion inhibitor in the primary cooling system
B . the level of the freshwater expansion tank
C . varying the engine load to meet temperature requirements
D . the operation of the thermostatic valve
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The expansion tank for a diesel engine closed cooling system is designed to maintain a constant head on the system and ().
A . reduce water temperature
B . reduce water turbulence
C . provide an air cushion
D . allow for an increase in water volume as the engine warms u
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In a diesel engine exhaust system, the cooling of the exhaust gases below their dew point, will result in ()
A . increased engine back pressure
B . sulfuric acid corrosion
C . surface pitting of the turbocharger
D . moisture impingement on the turbocharger compressor blade
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In the closed cooling system, the water ().
A . is made to circulate out of the system
B . is made to circulate within the system
C . is made circulate within the system
D . is made circulate out of the system
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Which of the following problems can cause fluctuating pressures in the closed cooling system of a main propulsion diesel engine?()
A . Defective temperature controls in the system
B . Cavitation in the cooling water pump
C . Opened vent in the cooling system
D . Restricted water passages in the engine
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If the coolant temperature of a closed cooling water system for a diesel engine gradually increases, the trouble usually is ()
A . a broken shaft on the freshwater pump
B . an excessive accumulation of scale exchanger
C . an incorrect thermostatic element operating range
D . lube oil in the cooling water
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There is a () system lubricating the running gear and cooling the piston and sometimes lubricating the cylinders.
A . recirculating
B . total loss
C . cooling
D . refrigeratio
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In motor-ships, (), after passing through main and motion bearings and oil cooled pistons, etcis either retained in the bedplate.
A . the fuel oil
B . the lubricating oil
C . the refrigerating oil
D . the hydraulic oil
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Which of the following statements is correct concerning diesel engine cooling water systems?()
A . Each engine must have its own engine driven cooling water pump capable of providing cooling for all ranges of operation
B . propulsion engines with bores exceeding 200 mm are to be fitted with a means to display the cooling water temperature of each cylinder
C . At least two independent sea suctions are to be provided for supplying water to the engine jackets or to the heat exchangers
D . Suitable strain are to be fitted between the circulating pumps and heat exchangers when sea water is used for direct cooling
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The piston crown employs the usual jet-shaker principle with an arrangement of cooling bores in the crown so that the surface temperatures of the crown are moderate with a very even distribution.
A.water cooling
B.oil cooling
C.air cooling
D.combined cooling
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On engines having oil cooled pistons the lubricating oil pre-heater must be put into operation and the rate of heating so ______ that the temperature of the piston cooling oil returns are 32 to 35℃ over a period of at least two hours.
A.slow
B.quick
C.arranged
D.high