更多"The purpose of an air compressor un"的相关试题:
[单项选择]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
[单项选择]If an air compressor is used to supply air primarily to the combustion control system and other pneumatic controllers, the entire system is known as the ().
A. control air system
B. forced draft air system
C. supply air system
D. ships service air system
[单项选择]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
[单项选择]The air compressor pumps air to the ().
A. air cylinder
B. combustion chamber
C. steam drum
D. expansion tank
[单项选择]Air compressors are equipped with unloading systems for the purpose of().
A. removing all but the frictional load during starting
B. relieving intercoolers of high temperature buildups
C. providing high starting torque in the drive motor
D. seating valve plates during compressor shutdown
[单项选择]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
[单项选择]The purpose of a temperature sensing device installed in the stack of a small automatically fired auxiliary steam boiler is to secure the oil burner()
A. in the event of a flame failure
B. in the event of a stack fire
C. when the water level reach the crown sheet
D. when the feed pump discharge pressure drops to a preset minimum
[单项选择]The device, which is installed in the compressor suction line to prevent liquid from entering the compressor when hot gas defrosting, is called a()
A. re-evaporator
B. receiver
C. dehydrator
D. solenoid
[单项选择]The purpose of compressing the air within the cylinder of a diesel engine is to ()
A. produce the heat for ignition
B. decrease injection lag
C. increase ignition delay
D. aid in exhausting burnt gases
[单项选择]If the electric motor driving an air compressor fails to start, the cause may be a ().
A. leaking unloader
B. tripped circuit breaker
C. control line leak
D. defective pop valve
[单项选择]If an electric motor driven air compressor fails to start, it may be due to a ().
A. leaking discharge valve
B. jammed suction valve
C. tripped overload relay
D. broken discharge un-loader
[单项选择]A dirty intercooler on an air compressor will cause ().
A. damage to the un-loader operating diaphragm
B. an increase in current flow to the motor
C. high pressure in the receiver and filter
D. an excessive consumption of crankcase oil
[单项选择]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
[单项选择]If a reciprocating air compressor has a knock occurring in frequency with its operating RPM, the cause is probably ().
A. misalignment or worn main bearings
B. insufficient cylinder lubrication
C. defective or poorly fitted valves
D. all of the above
[单项选择]If an air compressor is used to supply compressed air to outlets throughout the engine room and on deck of a vessel, the system is known as the ().
A. combustion control air system
B. supply air system
C. ships service air system
D. low pressure deck air system
[单项选择]The high air velocity leaving the compressor of an exhaust gas turbocharger is converted to pressure in the ()
A. inlet nozzle ring
B. turbine wheel blade
C. diffuser passages
D. inlet vol
[单项选择]A person may operate an air compressor in which of the following areas on board a tank barge?()
A. Pumproom
B. Generator room
C. A space adjacent to a cargo tank
D. A space two meters from a cargo valve