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单选题
In the starting system, the automatic valve is controlled by(), and the cylinder start valves are controlled by()
A
pilot air;pilot air
B
handle;solenoid
C
handle;pilot air coming through the distributor
D
solenoid;pilot air coming through the distributor
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考题
第二组Under normal operation, some lubrication oil mist may be discharged from the air compressor to the air start system. This oil may be from excess compressor cylinder lubrication, from faulty oil scraper rings, or may even be suspended oil vapor contaminating the engine room atmosphere and drawn in at the compressor suction. Oil discharge is kept to a minimum by draining the after cooler, air receiver and starting system. If small quantities of lubrication oil do get passed into the starting air system, they will deposit as thin moist film over internal pipe surfaces but are not readily combustible. If a cylinder non-return valve leak while the engine is in operation, some hot gas, possibly with unburned fuel and cylinder lubrication oil, may be blown through the valve to the adjacent air manifold. With further heating from the leaky valve, this, together with the already deposited oil film, will carbonize and form. incandescent carbon. If starting air is applied to the system while still hot, the high pressure air coming into contact with the burning carbon may cause an explosion. Such an explosion will cause a flame to pass back through the air start pipe system, evaporating the deposited oil film and igniting it in the presence of air. Very high velocities and shockwaves are generated which may rupture pipes and fittings.Alternatively, if excessive oil has entered the air start system, a mixture of air and oil droplets may be discharged through the open cylinder non-return valve during starting. This spray may ignite due to high temperatures in the cylinder, causing a flame through the still open valve to the air manifold.To prevent an explosion, air start valves must be correctly maintained and lubricated to ensure correct timing and free movement with positive closing. Oil in the system must be kept to a minimum, pipe lines must be drained and cleaned internally when necessary and oil discharge from air compressors must be kept to a minimum by good maintenance.The passage is mainly aboutA.crankcase explosionB.scavenge box fireC.starting air pipeD.the danger of explosion in the starting air system
考题
In an operating diesel engine, which of the following conditions is an indication of a leaking air starting valve?A.Noise coming from that air starting valveB.Continuous operation of the starting air compressorC.Zero air pressure in the air starting systemD.Overheated starting air pipe to the cylinder head
考题
The fuel oil supply system to an automatic auxiliary boiler, will automatically shutdown if the boiler ______.A.steam demand is highB.salinity is highC.safety valve simmers(爆发)D.burner flame is extinguished
考题
In the event of the cylinder starting valve leakage ______would pass into the air pipes and ignite the oil deposited.A.cooling waterB.vapor from the boilerC.starting airD.hot gases
考题
单选题Vessels having main engines arranged for air starting are to be provided with at least ()A
one automatic drain serving both containersB
two air starting containers of approximately equal sizeC
one control air container and one starting air containerD
one additional means of starting the main engine
考题
单选题Each inert gas system gas main must have an automatic shut down valve at the outlet of the gas production plant. This valve must close automatically upon().A
cargo pump failureB
blower failureC
deck seal low water levelD
low inert gas temperature
考题
单选题The opening or closing of the cylinder starting valve is controlled by ().A
the starting air distributorB
the cut-off valve on the air mainC
the main starting valveD
the air bottle control valve
考题
单选题Which of the following may cause that an engine doesnt turn on starting air?()A
too low starting air pressureB
main starting valve closedC
neither A nor BD
A and B
考题
单选题Which of the following methods is used to prevent throttling of compressed air through the diesel engine air starting valves?()A
Holding the valve open for a long periodB
Increasing the starting air pressure usedC
Opening the stating air valve quicklyD
Reducing the starting air valve size
考题
单选题The mechanical exhaust valve operation system is replaced by()in an electronic controlled ME engine.A
a system with a Hydraulic Power Supply (HPS) unitB
a system with roller guides for exhaust valvesC
a system with an electronically controlled Alpha LubricatorD
a system directly powered by electric motor
考题
单选题Which of the listed items should be secured before performing any maintenance on a solenoid operated air start valve?()A
Electric power and starting airB
Lube oil standby pump and control airC
Hydraulic switch and engage jacking gearD
Motor drain and pneumatic control system power
考题
单选题Diesel engine air start valve timing is controlled by()A
engine operating speedB
an air manifoldC
a hydraulic distributorD
individual cams and valve gear
考题
单选题Which of the following may cause that an engine doesnt run on starting air?()A
too low starting air pressureB
main start valve closedC
neither A nor BD
A and B
考题
单选题In the starting system, the automatic valve is controlled by(), and the cylinder start valves are controlled by()A
pilot air;pilot airB
handle;solenoidC
handle;pilot air coming through the distributorD
solenoid;pilot air coming through the distributor
考题
单选题The fuel oil supply system to an automatic auxiliary boiler, will automatically shutdown if the boiler ()A
steam demand is highB
salinity is highC
safety valve simmersD
burner flame is extinguished
考题
单选题Starting air valves are held firmly on their seats by()A
cam rollers on the camshaftB
spring forceC
air pressure on top of the valve differential pistonD
air pressure on the bottom of the valve differential piston
考题
单选题To add refrigerant to the low side of an air conditioning system, the refrigerant should be introduced through the ()A
suction service valve as a vaporB
suction service valve as a liquidC
discharge service valve as a vaporD
charging valve as a liquid
考题
单选题When starting a centrifugal pump, the discharge valve should be ().A
closedB
opened fullyC
cracked openD
partly open
考题
单选题The cylinder cover is not provided with ().A
fuel valveB
lubricatorC
indicator valveD
the starting valve
考题
单选题In a refrigeration system, if the cooling water to the condenser fails, the().A
box temperature solenoid valve will closeB
expansion valve will closeC
compressor will shutdownD
king valve will open
考题
单选题The low pressure side of a refrigeration system is considered to exist from the ().A
expansion valve to the compressorB
receiver to the expansion coilC
expansion valve to the evaporatorD
condenser to the expansion valve
考题
单选题When the starting air valve closes on one cylinder, another starting air valve has () opened on another cylinder whose piston has just commenced its downward stroke.A
justB
nearlyC
merelyD
already
考题
单选题In an operating diesel engine, which of the following condition is an indication of a leaking air starting valve?()A
noise coming from that air starting valveB
continuous operation of the starting air compressorC
zero air pressure in the air starting systemD
overheated starting air pipe to the cylinder head
考题
单选题The air distributor is conventionally driven by() and distributes into each cylinder by() certain sequence.A
camshaft;fresh airB
camshaft;starting airC
electronic motor which is controlled by a computer;fresh airD
electronic motor which is controlled by a computer;starting air
考题
单选题The diesel engine valve subjected to most severe conditions of service is the ().A
cylinder exhaust valveB
air starting valveC
air inlet valveD
cylinder relief valve
考题
单选题The timing of diesel engine air starting valves is controlled by()A
the air start valve timing gears and rodsB
a cylinder check valveC
individual cams and valve gearD
an air manifold poppet valve
考题
单选题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 systemB
the level of the freshwater expansion tankC
varying the engine load to meet temperature requirementsD
the operation of the thermostatic valve
考题
单选题Control valves of a CO2 system may be located within the protected space when().A
it is impractical to locate them outsideB
there is also a control valve outsideC
the CO2 cylinders are also in the spaceD
an automatic heat-sensing trip is installed
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