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Open the （）before starting an air compressor.
A . unload valve
B . cooling water
C . oil cup
D . sum
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A non-return valve in the air delivery line near to the compressor must be （）type similar to the compressor discharge valve.
A、the low inertia
B、the high inertia
C、the low velocity
D、the high velocity
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Excessive lube oil consumption by a reciprocating air compressor can be caused by （）.
A、using a slightly dirty air filter
B、using oil having an excessive viscosity
C、intercooler or after-cooler leaks
D、carrying the oil level higher than normal
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The （） stage air compressors are widely used on board the ship.
A . single
B . Ⅱ
C . Ⅲ
D . multiple
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A reciprocating air compressor is running roughly and vibrating excessively, indicating that the （）.
A、compressor is overloaded
B、motor is overloaded
C、foundation bolts are loose
D、belts are too tight
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In order to distribute the side pressures over a wide area of the cylinder walls and liners, which of the listed types of pistons are used in modem low pressure air compressors?（）
A . Differential
B . Trunk
C . Barrel
D . Valve-in-head
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Intercoolers installed on starting air compressors, reduce the possibility of（）
A . dust entering the high pressure stage
B . lube oil carbonization
C . discharge pulsations
D . inter-stage vapor lock
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By far the greatest item of maintenance of the reciprocating air compressors concerns （）.
A . the lubrication
B . the cooling
C . the moisture separation
D . the valve
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On opposite ends of a single shaft of a turboblower are a gas driven （）and a air compressor, which are sealed each other.
A . charge air receiver
B . scavenging air belt
C . turbine
D . air cooler
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On small, low pressure, air compressors, the cylinders are usually lubricated by the （）.
A . splash method
B . mechanical force feed lubricators
C . detached sump method
D . internal cooling passages in the crankshafts and connecting rod
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The purpose of an air compressor unloading device is to （）
A . drain water from the air receiver
B . drain water from the cylinders
C . delay the compression process until the motor is up to speed
D . check pump alignment
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To obtain maximum efficiency, two stage air compressors are usually （）.
A . horizontally mounted
B . never fitted with intake filters
C . fitted with intercoolers
D . operated in an unloaded condition at all time
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A dirty intercooler on the ship service air compressor will result in （）.
A . decreased compression ratio
B . higher than normal power consumption
C . un-loader malfunction
D . water in the lubricating oil
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Before starting an air compressor, It should be （）.
A . unloaded
B . primed
C . filled with water
D . greased
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Condensate must be drained periodically from the air compressor receivers to prevent （）.
A . second stage cylinder lockup
B . oil sump contamination
C . faulty operation of pneumatic valves
D . corrosion of air receiver baffle
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A knocking sound from one cylinder of an operating air compressor indicates （）.
A . a defective or broken high pressure un-loader
B . a loose valve plate
C . excessive overload
D . no compressio
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Which of the following problems could cause air to blow out through the inlet air filter of a running compressor?（）
A . Excessive compression in the cylinder
B . A broken intake valve
C . A dirty inlet filter element
D . An improperly adjusted discharge valve
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A （） in the air delivery line near to each compressor is essential.
A . butterfly valve
B . globe valve
C . gate valve
D . non-return valve
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Broken valve strips in an operating low pressure, air compressor will cause （）.
A、an immediate crankcase explosion
B、oil contamination in the compressed air
C、a decrease in compressor capacity
D、no immediate loss of the compressed air capacity
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The air charge leaving an intercooler, or after-cooler of an air compressor can be expected to be （）.
A、superheated
B、super-cooled
C、at or below the dew point
D、All of the above
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The unloading system on an air compressor will （）.
A . increase compressor discharge pressure on demand
B . increase compressor operating speed as necessary
C . allow the motor to turn the compressor opposed only by friction
D . reduce the compressor frictional load when starting
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Air compressor cylinder un-loaders enable the compressor to （）.
A . vary their speed according to temperature and load
B . start and come up to speed before air compression begins
C . change speed according to overload demands
D . reduce compressed air charge density
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Air blowing from the intake air filter of an operating air compressor indicates （）.
A、broken inlet valves
B、broken discharge valves
C、pulsations in the air distribution system
D、overloading of the air distribution system
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The loss of （） from an air compressor could lead to an overheated air discharge and possibly an explosion in the pipelines leading to the air reservoir.
A、lubricating oil
B、compressed air
C、cooling water
D、sealing ring
