RSES Refrigerant Management 2 — Questions and Answers
Question 1: Under EPA Section 608, what is the maximum allowable annual leak rate for refrigerant in a commercial refrigeration system containing more than 50 lbs of refrigerant?
- 10%
- 20% (Correct answer)
- 30%
- 50%
Correct answer: 20%
EPA Section 608 sets the annual leak rate threshold at 20% for commercial refrigeration systems with more than 50 lbs of refrigerant.
Question 2: Which refrigerant blend is classified as a zeotropic mixture, meaning its components evaporate and condense at different temperatures?
- R-500
- R-502
- R-404A (Correct answer)
- R-134a
Correct answer: R-404A
R-404A is a zeotropic blend of R-125, R-143a, and R-134a that exhibits temperature glide during phase change.
Question 3: When recovering refrigerant from a system with a compressor that is not operational, a technician must use what type of recovery method?
- Vapor recovery only
- Liquid recovery only
- System-dependent recovery (Correct answer)
- Push-pull recovery
Correct answer: System-dependent recovery
System-dependent (passive) recovery relies on the system's own components and is only viable when the compressor is operable; with a non-operational compressor, a self-contained recovery unit must be used.
Question 4: What does the term 'temperature glide' refer to in refrigerant blends?
- The difference between suction and discharge temperatures
- The range of temperatures at which a blend changes phase at constant pressure (Correct answer)
- The subcooling achieved at the condenser outlet
- The superheat setting of the expansion valve
Correct answer: The range of temperatures at which a blend changes phase at constant pressure
Temperature glide is the difference between the bubble point and dew point temperatures of a zeotropic blend during phase change at constant pressure.
Question 5: A recovery cylinder must not be filled beyond what percentage of its rated capacity by weight?
- 60%
- 70%
- 80% (Correct answer)
- 90%
Correct answer: 80%
DOT regulations require that refrigerant recovery cylinders not be filled beyond 80% of their rated capacity by weight to allow for thermal expansion.
Question 6: Which organization sets the safety classification system (A1, A2, B1, B2, etc.) for refrigerants used in the HVACR industry?
- EPA
- ASHRAE (Correct answer)
- DOT
- UL
Correct answer: ASHRAE
ASHRAE Standard 34 establishes the refrigerant safety classification system using letter-number designations for toxicity and flammability.
Question 7: R-410A operates at significantly higher pressures than R-22. Approximately how much higher are its operating pressures?
- 25% higher
- 50% higher
- 70% higher
- Twice as high (Correct answer)
Correct answer: Twice as high
R-410A operates at approximately twice the pressure of R-22, requiring system components specifically rated for its higher pressure range.
RSES Refrigerant Management 2
Under EPA Section 608, what is the maximum allowable annual leak rate for refrigerant in a commercial refrigeration system containing more than 50 lbs of refrigerant?