RSES Refrigerant Management 3 — Questions and Answers
Question 1: What is the primary purpose of adding a desiccant dryer to a refrigeration system?
- To remove non-condensable gases
- To remove moisture from the refrigerant circuit (Correct answer)
- To filter out compressor oil particles
- To reduce refrigerant velocity in the liquid line
Correct answer: To remove moisture from the refrigerant circuit
Desiccant dryers (filter-driers) absorb moisture from the refrigerant to prevent ice formation at the expansion device and acid formation in the system.
Question 2: Which refrigerant was the primary replacement for R-12 in automotive air conditioning systems?
- R-22
- R-134a (Correct answer)
- R-404A
- R-410A
Correct answer: R-134a
R-134a replaced R-12 in automotive AC systems beginning in 1994 model year vehicles because it has zero ozone depletion potential.
Question 3: Non-condensable gases trapped in a refrigeration system will cause which of the following symptoms?
- Lower than normal discharge pressure
- Higher than normal discharge pressure (Correct answer)
- Lower than normal suction pressure
- Increased subcooling at the condenser
Correct answer: Higher than normal discharge pressure
Non-condensable gases (such as air or nitrogen) accumulate in the condenser and raise the discharge pressure above what the refrigerant saturation pressure would be at the condenser temperature.
Question 4: Under the Montreal Protocol's Kigali Amendment, HFC refrigerants are being phased down primarily because of their contribution to which environmental problem?
- Ozone depletion
- Ground-level ozone formation
- Global warming / climate change (Correct answer)
- Acid rain
Correct answer: Global warming / climate change
The Kigali Amendment targets HFCs due to their high global warming potential (GWP), as they do not deplete ozone but are potent greenhouse gases.
Question 5: A technician discovers that a system's refrigerant has been contaminated with the wrong type of refrigerant. What is the correct procedure?
- Add more of the correct refrigerant to dilute the contaminant
- Recover the entire charge and send to a reclaimer, then recharge with virgin refrigerant (Correct answer)
- Run the system at reduced capacity until the contamination clears
- Replace only the compressor oil and recharge
Correct answer: Recover the entire charge and send to a reclaimer, then recharge with virgin refrigerant
Contaminated refrigerant must be fully recovered and sent to a certified reclamation facility; the system should then be recharged with verified virgin or reclaimed refrigerant.
Question 6: What is the GWP (Global Warming Potential) of R-22 relative to CO₂?
- Approximately 100
- Approximately 500
- Approximately 1,810 (Correct answer)
- Approximately 3,900
Correct answer: Approximately 1,810
R-22 has a GWP of approximately 1,810, meaning one pound of R-22 has the same greenhouse warming impact as 1,810 pounds of CO₂ over 100 years.
Question 7: Which type of refrigerant cylinder is used exclusively for shipping and cannot be refilled with refrigerant for resale?
- Recovery cylinder
- Disposable/non-refillable cylinder (Correct answer)
- DOT-4BA cylinder
- Returnable cylinder
Correct answer: Disposable/non-refillable cylinder
Disposable (non-refillable) cylinders are single-use shipping containers; refilling them with refrigerant for resale is illegal under EPA and DOT regulations.
RSES Refrigerant Management 3
What is the primary purpose of adding a desiccant dryer to a refrigeration system?