CFC Alternative Refrigerants & Transitions 4 — Questions and Answers
Question 1: Which of the following refrigerants has the highest Ozone Depletion Potential (ODP)?
- R-22
- R-11 (Correct answer)
- R-134a
- R-410A
Correct answer: R-11
R-11 (CFC-11) has an ODP of 1.0, which is the reference value against which all other refrigerants are measured, making it the highest among common refrigerants.
Question 2: A technician retrofitting an R-22 system with R-422D must use which type of lubricant?
- Mineral oil only
- POE oil only
- Alkylbenzene oil or mineral oil (Correct answer)
- No lubricant change is required
Correct answer: Alkylbenzene oil or mineral oil
R-422D is compatible with existing mineral oil or alkylbenzene oil in R-22 systems, making it a popular retrofit refrigerant because oil change is not required.
Question 3: What is the primary environmental advantage of natural refrigerants such as CO₂ (R-744) and ammonia (R-717)?
- They have zero toxicity
- They have zero or near-zero GWP and zero ODP (Correct answer)
- They are compatible with all existing equipment
- They operate at lower pressures than HFCs
Correct answer: They have zero or near-zero GWP and zero ODP
Natural refrigerants like CO₂ and ammonia have zero ODP and GWPs of 1 (CO₂) or 0 (ammonia), making them environmentally superior long-term alternatives.
Question 4: Why must technicians use dedicated recovery equipment when handling A2L refrigerants like R-32 or R-454B?
- A2L refrigerants dissolve standard hose materials
- Standard recovery equipment may contain ignition sources that could ignite mildly flammable refrigerants (Correct answer)
- A2L refrigerants require higher vacuum levels
- Standard equipment cannot reach required recovery pressures
Correct answer: Standard recovery equipment may contain ignition sources that could ignite mildly flammable refrigerants
A2L refrigerants are mildly flammable, and standard recovery equipment may contain electrical sparks or hot surfaces that could act as ignition sources.
Question 5: R-507A is primarily used as a replacement for which high-GWP refrigerant in commercial refrigeration?
- R-22
- R-12
- R-502 (Correct answer)
- R-134a
Correct answer: R-502
R-507A was developed as an azeotropic HFC blend to replace R-502 in medium and low-temperature commercial refrigeration applications.
Question 6: In the context of refrigerant transitions, what does the term 'retrofit' mean?
- Installing a completely new refrigeration system
- Modifying an existing system to operate with a different refrigerant (Correct answer)
- Recovering and recycling the original refrigerant
- Replacing only the compressor and condenser
Correct answer: Modifying an existing system to operate with a different refrigerant
A retrofit involves converting an existing refrigeration or air conditioning system to use a different, typically more environmentally acceptable refrigerant.
Question 7: Which characteristic makes propane (R-290) challenging for widespread use in large commercial HVAC systems despite its low GWP?
- Its ODP is too high
- Its charge size is severely limited due to its A3 (highly flammable) classification (Correct answer)
- It requires POE lubricants not available commercially
- It is not compatible with copper tubing
Correct answer: Its charge size is severely limited due to its A3 (highly flammable) classification
R-290 is classified A3 (highly flammable), and safety standards strictly limit charge sizes, making it impractical for large commercial systems that require substantial refrigerant quantities.
CFC Alternative Refrigerants & Transitions 4
Which of the following refrigerants has the highest Ozone Depletion Potential (ODP)?