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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
just
B
nearly
C
merely
D
already
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更多 “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” 相关考题
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
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
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
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When operating the air supply system in a covered lifeboat the（）.A
fuel supply valve should be closedB
hatches，doors，and oar ports should be closedC
air cylinder shut-off valve should be closedD
engine should be shut off
考题
单选题When the order （） is received from the bridge, the main air stop valve in the starting air line should be shut.A
stand-by engineB
full aheadC
finished with engineD
full away
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When an air started, four-stroke/cycle diesel engine is being cranked, the starting air is admitted to each cylinder during what would normally be the（）A
intake strokeB
compression strokeC
power strokeD
exhaust stroke
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During the fuel injection period, fuel pressure must exceed cylinder gas pressure to （）.A
ensure penetration and distribution of the fuel in the combustion chamberB
ensure the needle valve is flushed clean during each injectionC
prevent combustion gas blowback into the open needle valveD
prevent reflected pressure waves when the needle valve closes
考题
单选题When starting an engine, the compressed air enters the cylinder when the corresponding piston is in position of its（）A
suction strokeB
compression strokeC
power strokeD
exhaust stroke
考题
单选题The compressed air is admitted to each cylinder through a cam operated by starting air valve when the piston has just passed its （）.A
BDCB
TDCC
BBDCD
ATDC
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Each cylinder has one starting valve which is usually opened by air pressure and closed by （）A
nuts and boltsB
new jointsC
spring forceD
sealing rings
考题
单选题Compressed air is supplied by air compression to （）.A
the air receiversB
the starting valvesC
the cylinder coversD
the distributors
考题
单选题（） in what position the engine stops there will always be at least one of the cylinders with its starting air valve open to admit compressed air to start the engine.A
BecauseB
Owing toC
ForD
No matter
考题
单选题A knocking sound from one cylinder of an operating air compressor indicates （）.A
a defective or broken high pressure un-loaderB
a loose valve plateC
excessive overloadD
no compression
考题
单选题In order to properly remove air from the casing of a centrifugal pump when starting, the pump should have a （）.A
positive headB
negative suction headC
mechanical sealD
vent valve attached to the casing at the top of the volute
考题
单选题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In an engine with air inlet valve and exhaust valve on its cylinder heads the fresh air will enter into the cylinder （） and the gases exhaust （）, there being an adequate overlap between the inlet opening and the exhaust closing.A
downwards；upwardsB
upwards；downwardsC
downwards；downwardsD
upwards；upwards
考题
单选题The starting air entering the cylinder begins when the piston（）A
has nearly come to the TDCB
has just past the TDCC
has nearly come to the BDCD
has just past the BDC
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 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 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Failure to open the diesel engine test cocks after a long period of shutdown, prior to starting may result in （）A
an air bound fuel systemB
damage to cylinder heads and pistonsC
excessive fuel injectionD
excessive air valve lift
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