Book 2: 5-26 - "Compression Refrigeration System Operations" Flashcards
On smaller capacity refrigeration compressors _____ valves prior to starting.
Select one:
A. Close the suction and discharge
B. Open the suction and discharge
C. Close the suction and open the discharge
D. Open the suction and close the discharge
E. Open the bypass
B. Open the suction and discharge
What is the symptom of a refrigeration system when the system is short of capacity due to a clogged strainer?
Select one:
A. There is a temperature difference in liquid line before and after strainer
B. Superheat too high
C. Flash gas in liquid line
D. Expansion valve stuck
E. Expansion valve hisses
A. There is a temperature difference in liquid line before and after strainer
The vane closed switch is in the motor starting circuit so that the compressor can only be started when the vanes are in the _____ position.
Select one:
A. Closed position
B. Compressor open
C. Compressor closed
D. Evaporator closed
E. Evaporator open
A. Closed position
The information card that code requires for refrigeration systems over 125 kW must include all of the following information except:
Select one:
A. The name, address, and telephone number of the regulatory authority
B. Instructions for shutting down the system in case of emergency
C. Instructions to notify said authority immediately in case of emergency
D. Instructions for starting up the system in case of emergency
E. The name, address and day and night telephone numbers for obtaining service
D. Instructions for starting up the system in case of emergency
The low oil pressure cutout switch is a safety shutdown device that prevents compressor operation when oil pressure is:
Select one:
A. Below the refrigerant level
B. Below a safe minimum value
C. Too cold
D. Too high
E. Too low in the crankcase
B. Below a safe minimum value
The chilled water temperature switch will shut down the compressor if the temperature of the water leaving the chiller drops to approximately:
Select one:
A. 2.5°C - 3°C (36.5°F – 37.5°F)
B. 1.5°C - 2°C (35°F – 35.5°F)
C. 1°C – 1.5°C (34°F - 35°F)
D. 0°C – 0.5°C (32°F - 33°F)
E. 2°C – 2.5°C (35.5°F – 36.5°F)
A. 2.5°C - 3°C (36.5°F – 37.5°F)
What is the symptom of a refrigeration system that has high suction pressure due to an oversized expansion valve?
Select one:
A. Undersized compressor
B. Contaminants in the refrigerant
C. Non-condensables in the system
D. An abnormally cold suction line
E. Fouled condenser
D. An abnormally cold suction line
Refrigeration system log sheets can be obtained from all of the following except:
Select one:
A. Refrigeration system manufacturers
B. Insurance companies
C. Government agencies
D. Developed by the refrigeration system operator
E. Inspection companies
C. Government agencies
Why must you avoid running a refrigeration system below 14 KPa when pumping down?
Select one:
A. The systems heat exchangers will ice up
B. Too much refrigerant will be required for a recharge
C. The heat exchanges may collapse due to the low pressure
D. The compressor will need to be stopped to prevent it running dry
E. A slightly positive system pressure is required to prevent air infiltration
E. A slightly positive system pressure is required to prevent air infiltration
The benefits of a good preventative maintenance program may included all of the following except:
Select one:
A. Reduced life expectancy of plant and equipment
B. Better means of identifying causes of breakdowns
C. Accumulation of history records for each piece of equipment
D. Control of labour and material cost
E. Reduced spare parts inventory required
A. Reduced life expectancy of plant and equipment
What is the symptom of a refrigeration system when the compressor suction pressure is too low due an obstructed expansion valve?
Select one:
A. Compressor short-cycles
B. Lack of refrigerant
C. Loss of capacity
D. Conditioned space too cold
E. Evaporator dirty or iced up
C. Loss of capacity
If the refrigeration compressor is equipped with an oil sump heater, ensure it is energized and that the oil temperature is high enough to drive off any:
Select one:
A. Carbon dioxide
B. Water
C. Oil
D. Refrigerant
E. Air
D. Refrigerant
Most refrigeration systems are controlled by a motor demand limiter that limits the:
Select one:
A. Maximum refrigerant flow to the compressor
B. Maximum current flow to the compressor motor
C. Minimum refrigerant flow to the evaporator
D. Minimum current flow to the compressor motor
E. Maximum water flow to the condenser
B. Maximum current flow to the compressor motor
When a refrigeration system is to be down for a prolonged period of time, it should be “pumped down” and all refrigerant stored in the:
Select one:
A. Receiver
B. Evaporator
C. Condenser
D. Accumulator
E. Compressor
A. Receiver
The purging unit of the refrigeration system should be operated for at least _____ minutes before the compressor is started (time depends on the size of the system).
Select one:
A. 10
B. 5
C. 15
D. 20
E. 25
A. 10
