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1. The efficiency of the refrigerant cycle is affected by the operation of the condenser. Of the following, a more efficient centrifugal compressor operation results from:
A: Raising the condenser liquid level to the maximum
B: Lowering the chilled water set point
C: Raising the condenser head pressure
D:Lowering the condensing pressure
D:Lowering the condensing pressure
2. The heat removed from the refrigerant in a condenser is:
A:Sensible and latent heat
B:Latent heat only
C:Radiant heat only
D:Sensible heat only
A:Sensible and latent heat
3. The refrigerant unit that you have been assigned to is being taken out of service for a major repair.You have been assigned to withdraw refrigerant for storage in suitable containers. According to the New York City fire code, you must ensure that the containers:
A:Do not weigh more than 200 pounds when filled
B:Are approved by the US Department of Transportation
C:Are approved by the OSHA Association
D:Do not exceed 55 Gallon in capacity
B:Are approved by the US Department of Transportation
4. Which of the following best describes how the cylinder unloader work?
A:Keep in the suction valve opened while the compressor is in the return stroke
B:Controls the clearance volume in the compressor with a solenoid
C:Controls the opening of the passage into the compressor with variable vanes
D:Unloads the piston to create less pressure
A:Keep in the suction valve opened while the compressor is in the return stroke
5. In most semi Hermetic compressors, the suction vapor is used to:
A:Removes oil from the motor housing
B:Cools the motor
C:Minimizes oil foaming
D:Removes oil foam from the shaft
D:Removes oil foam from the shaft
6. The amount of refrigerant that flows through the orifices of a economizer is determined by the:
A:Number of economizer stages
B:Temperature of the high side refrigerant
C:Number of compressor stages
D:Difference between the high side and low side pressure
D:Difference between the high side and low side pressure
7. The installation of an inline refrigerant cleaning system is advisable:
A:For high pressure refrigerant systems
B:To purge non-condensables
C:For systems using toxic refrigerant
D:To remove impurities from the system
D:To remove impurities from the system
8. The type of refrigerant system that is least likely to leak refrigerant into the building space that are being cooled:
A:The direct vented closed system
B:The direct closed system
C:Any system using reciprocating compressor
D:The indirect system
D:The indirect system
9. The suction pressure of a reciprocating compressor is 65 PSIG. The discharge pressure of this compressor is 120 PSIG. The atmospheric is 14.7 PSI. The compression ratio for the given condition is closest to:
A. 2.07
B. 4.41
C.1.69
D. 1.84
C.1.69
10. A superheated vapor is a:
A:Dry vapor at the saturation temperature
B:Dry saturated vapor
C:Dry vapor above the saturation temperature
D:Vapor with minimal amount of included liquid
C:Dry vapor above the saturation temperature
11. A refrigerant engineer verifies that a condenser water pump is cavitating. Of the following the most likely cause for this condition is:
A:A faulty cooling tower water level controller
B:Operating at sustaining high loads
C:Too long a period between pump servicing
D:Refrigerant leaks through the pumps packing
A:A faulty cooling tower water level controller
12. A centrifugal water pump is known as a lift pump when the:
A.:The pump lifts the water into the pump upon startup
B:the water supply to the pump suction inlet is below the pump level
C:The discharge head exceed 150 feet
D:The pump is started with the suction valve open
B:the water supply to the pump suction inlet is below the pump level
13. A TXV is used to maintain constant:
A. Refrigerant flow
B. Evaporator pressure
C. Evaporator pressure drop
D:Evaporator superheat
D:Evaporator superheat
14. The chilled water supply to the building is 55F. If the chiller is being used for human comfort, should you be concerned about this, and why?
A:Yes, this temperature is too low for human comfort purpose
B:Yes, this temperature is too high for human comfort purpose
C: No, 55F is within an acceptable range
D:No, temperature gauges often give false high readings
B:Yes, this temperature is too high for human comfort purpose
15. The packing gland of a centrifugal pump serves to:
A:Keep the bearing cooled
B:Keeps air out of the pumps when the impeller housing is under negative pressure
C: The drip part of the packing gland gives evidence that there is water in the pump
D: All of the answers are correct
C: The drip part of the packing gland gives evidence that there is water in the pump