HVAC EPA 608 Refrigerant Certification 4 — Questions and Answers
Question 1: What critical safety hazard is associated with refrigerant cylinders exposed to direct flame or excessive heat?
- Implosion due to low pressure
- BLEVE (Boiling Liquid Expanding Vapor Explosion) (Correct answer)
- Refrigerant polymerization
- Cylinder corrosion and pinhole leaks
Correct answer: BLEVE (Boiling Liquid Expanding Vapor Explosion)
Overheated refrigerant cylinders can experience a BLEVE — a catastrophic explosion caused by rapid vaporization of liquid refrigerant exceeding cylinder pressure limits.
Question 2: What does a subcooling measurement tell a technician about a refrigeration system?
- How much the refrigerant temperature exceeds saturation temperature at the evaporator outlet
- How much the liquid refrigerant temperature is below its saturation temperature at the condenser outlet (Correct answer)
- The amount of moisture in the refrigerant
- The temperature difference across the expansion device
Correct answer: How much the liquid refrigerant temperature is below its saturation temperature at the condenser outlet
Subcooling is the number of degrees the liquid refrigerant has cooled below its saturation (condensing) temperature, ensuring solid liquid reaches the expansion device.
Question 3: Which type of metering device maintains a constant evaporator superheat regardless of load changes?
- Fixed orifice (capillary tube)
- Thermostatic Expansion Valve (TXV/TEV) (Correct answer)
- Automatic Expansion Valve (AEV)
- Low-side float
Correct answer: Thermostatic Expansion Valve (TXV/TEV)
The TXV (Thermostatic Expansion Valve) senses evaporator outlet temperature and adjusts refrigerant flow to maintain a constant superheat set point.
Question 4: Under EPA 608, which of the following is NOT a recognized method for verifying that a leak repair was successful?
- Operating the equipment for 24 hours then verifying pressure holds
- Using an electronic leak detector to check repaired joints
- Pressurizing with nitrogen and checking for pressure drop
- Visually inspecting for oil staining only (Correct answer)
Correct answer: Visually inspecting for oil staining only
Visual inspection for oil staining alone is not an accepted verification method; EPA requires leak testing with detectors, pressure testing, or operational verification.
Question 5: What is the GWP of R-410A relative to CO2?
- Approximately 675
- Approximately 1,430
- Approximately 2,088 (Correct answer)
- Approximately 3,922
Correct answer: Approximately 2,088
R-410A has a GWP of approximately 2,088, making it a significant greenhouse gas and a target for phase-down under AIM Act regulations.
Question 6: An HVAC technician discovers a system has non-condensables mixed with the refrigerant. What is the recommended procedure?
- Vent the non-condensables to atmosphere and recharge
- Recover the refrigerant charge and send it to a certified reclaimer (Correct answer)
- Add more refrigerant to dilute the non-condensables
- Increase the condensing pressure to force non-condensables out
Correct answer: Recover the refrigerant charge and send it to a certified reclaimer
Refrigerant contaminated with non-condensables must be recovered and sent to a certified reclaimer; venting refrigerant to atmosphere is illegal under EPA 608.
Question 7: What is the purpose of the Schrader valve core on a refrigerant service port?
- To regulate refrigerant flow rate during normal operation
- To prevent refrigerant from escaping when service hoses are not connected (Correct answer)
- To filter moisture from the refrigerant
- To act as a check valve preventing liquid refrigerant backflow
Correct answer: To prevent refrigerant from escaping when service hoses are not connected
The Schrader valve core acts as a check valve in the service port, preventing refrigerant loss when service hoses or gauges are not connected.
HVAC EPA 608 Refrigerant Certification 4
What critical safety hazard is associated with refrigerant cylinders exposed to direct flame or excessive heat?