更多"In an air conditioning system, low "的相关试题:
[单项选择]In an alternating current electrical system, a low system power factor is a direct sign of （）
A. wasted energy
B. efficient operation
C. a short in the exciter field windings
D. an excessive number of minor system grounds
[单项选择]Air entering an air-cooled refrigeration system is indicated by （）.
A. frosting of the liquid line
B. higher than normal head pressure
C. a clear sight glass
D. abnormally cold reefer boxes
[单项选择]The refrigeration system low pressure cutout switch is actuated by （）.
A. an electric system manager
B. a sensing bulb at the tail coil of the evaporator
C. pressure changes in the suction line
D. failure of the king solenoid valve
[单项选择]Low compressor head pressure in a refrigeration system can be caused by（）.
A. insufficient condenser cooling water
B. excessive condenser cooling water
C. air in the refrigeration system
D. excessive refrigerant in the system
[单项选择]The purpose of the refrigeration system low pressure cutout switch is to （）
A. protect the compressor from liquid flood back
B. protect the compressor from low discharge pressure
C. start and stop the compressor upon system demand
D. start the compressor after a drop in the evaporator pressure
[单项选择]In an operating refrigeration system low on refrigerant, a liquid line sight glass will（）
A. be clear
B. be blue
C. be light green
D. show bubbles
[单项选择]Excessively low air pressure occurring in the intercooler of a reciprocating air compressor is caused by（）.
A. leaky discharge valves on the LP cylinder
B. leaky discharge valves on the HP cylinder
C. insufficient intercooler cooling
D. low ambient air pressure
[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]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]Low pressure air is usually taken through （） or pressure regulators to a low pressure reservoir supplying a ring main through driers.
A. globe valves
B. butterfly valves
C. gate valves
D. reducing valves
[单项选择]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 rods
[单项选择]To add refrigerant to the low side of an air conditioning system, the refrigerant should be introduced through the （）
A. suction service valve as a vapor
B. suction service valve as a liquid
C. discharge service valve as a vapor
D. charging valve as a liquid
[单项选择]The low pressure side of a refrigeration system is considered to exist from the （）.
A. expansion valve to the compressor
B. receiver to the expansion coil
C. expansion valve to the evaporator
D. condenser to the expansion valve
[单项选择]When operating the air supply system in a covered lifeboat the（）.
A. fuel supply valve should be closed
B. hatches，doors，and oar ports should be closed
C. air cylinder shut-off valve should be closed
D. engine should be shut off
[单项选择]In an air conditioning system, moisture is removed from the air by（）
A. filers
B. separators
C. ducted traps
D. dehumidifiers
[单项选择]Diesel engine air start system check valves are opened by （）
A. an air start cam
B. cylinder compression pressure
C. starting air pressure
D. valve springs
[单项选择]Purging air from a hydraulic system is necessary when（）
A. adding small amounts of oil to the system
B. the system has been overheated
C. the system has been drained and then filled with new oil
D. the system has been idle for a long period of time
