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第1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 valve
B.Continuous operation of the starting air compressor
C.Zero air pressure in the air starting system
D.Overheated starting air pipe to the cylinder head
第2题:
the starting air distributor
the cut-off valve on the air main
the main starting valve
the air bottle control valve
第3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 about
A.crankcase explosion
B.scavenge box fire
C.starting air pipe
D.the danger of explosion in the starting air system
第4题:
intake stroke
compression stroke
power stroke
exhaust stroke
第5题:
stand-by engine
full ahead
finished with engine
full away
第6题:
In the event of the cylinder starting valve leakage ______would pass into the air pipes and ignite the oil deposited.
A.cooling water
B.vapor from the boiler
C.starting air
D.hot gases
第7题:
fuel supply valve should be closed
hatches,doors,and oar ports should be closed
air cylinder shut-off valve should be closed
engine should be shut off
第8题:
Vessels having main engines arranged for air starting are to be provided with at least__.
A.one automatic drain serving both containers
B.two air starting containers of approximately equal size
C.one control air container and one starting air container
D.one additional means of starting the main engine
第9题:
too low starting air pressure
main starting valve closed
neither A nor B
A and B
第10题:
Holding the valve open for a long period
Increasing the starting air pressure used
Opening the stating air valve quickly
Reducing the starting air valve size