CFC Refrigerant Identification & Testing 2 — Questions and Answers
Question 1: What is the ASHRAE numerical designation for the refrigerant formerly known by the trade name Freon-12?
- R-11
- R-12 (Correct answer)
- R-22
- R-500
Correct answer: R-12
Freon-12 is designated R-12 under the ASHRAE refrigerant numbering system, a fully halogenated CFC that was phased out under the Montreal Protocol.
Question 2: What is the standard AHRI cylinder color for R-134a refrigerant?
- Light green
- White
- Sky blue (Correct answer)
- Rose/pink
Correct answer: Sky blue
R-134a cylinders are painted sky blue (light blue) per AHRI cylinder color-coding standards, distinguishing it from R-22 (light green) and R-12 (white).
Question 3: When using a refrigerant identifier and receiving a 'FAIL - mixed refrigerant' reading, what does this indicate?
- The identifier requires recalibration
- The cylinder contains two or more different refrigerants blended together (Correct answer)
- The refrigerant is too pure to identify correctly
- The refrigerant is a listed zeotropic blend
Correct answer: The cylinder contains two or more different refrigerants blended together
A 'mixed refrigerant' failure means the cylinder contains an unintended combination of different refrigerants that cannot be separated and must be sent for destruction, not recovery.
Question 4: What distinguishes R-410A from R-407C in terms of phase-change behavior during system testing?
- They have identical pressure-temperature relationships
- R-410A has minimal temperature glide while R-407C has a significant glide of 4-7°F (Correct answer)
- R-407C operates at higher pressures than R-410A
- R-410A has a larger temperature glide than R-407C
Correct answer: R-410A has minimal temperature glide while R-407C has a significant glide of 4-7°F
R-410A is a near-azeotropic blend with minimal temperature glide, while R-407C is zeotropic with a temperature glide of approximately 4-7°F, which affects P-T chart readings.
Question 5: What is the moisture content limit for reclaimed R-22 per AHRI Standard 700?
- 50 ppm by weight
- 10 ppm by weight (Correct answer)
- 100 ppm by weight
- 25 ppm by weight
Correct answer: 10 ppm by weight
AHRI Standard 700 limits moisture in reclaimed R-22 to 10 ppm by weight to prevent ice formation in expansion devices and hydrolysis that produces corrosive acids.
Question 6: What is the standard cylinder color assigned to R-12 refrigerant?
- Light green
- Orange
- White (Correct answer)
- Sky blue
Correct answer: White
R-12 refrigerant cylinders are painted white per AHRI cylinder color-coding conventions, distinguishing them from R-22 (light green) and R-134a (sky blue).
Question 7: What field test can be used to check for the presence of non-condensable gases in a refrigerant cylinder?
- Compare cylinder pressure to the P-T chart value for the measured cylinder temperature (Correct answer)
- Weigh the cylinder and compare to rated capacity on the label
- Shake the cylinder and listen for liquid movement inside
- Check the cylinder DOT label for listed non-condensable content
Correct answer: Compare cylinder pressure to the P-T chart value for the measured cylinder temperature
Non-condensable gases cause pressure to be higher than the P-T chart predicts for a given temperature because they do not condense and add to the total pressure.
CFC Refrigerant Identification & Testing 2
What is the ASHRAE numerical designation for the refrigerant formerly known by the trade name Freon-12?