更多"The unloading system on an air comp"的相关试题:
[单项选择]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
[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]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]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]Refrigeration system compressor crankcase sweating is an indication of ().
A. insufficient lube oil circulating through the system
B. excessive circulation of lube oil through the system
C. insufficient refrigerant in the system
D. an overworked compressor
[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]A refrigeration system compressor crankcase is sweating or unusually coldThis is an indication of().
A. a shortage of refrigerant in the system
B. air in the system
C. an accumulation of liquid refrigerant in the crankcase
D. a shortage of oil in the crankcase
[单项选择]If a refrigeration system compressor crankcase is sweating, you should ().
A. add refrigerant to the system
B. adjust the thermal expansion valve to the proper setting
C. adjust the float valve to the proper holding pressure
D. open the hand expansion valve
[单项选择]Sweating of the refrigeration system compressor crankcase is caused by ().
A. too much superheat
B. insufficient superheat
C. suction pressure too low
D. excessive refrigerant returning to the compressor
[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