A technician is performing a recovery on a high-pressure appliance containing 60 pounds of R-410A. The ambient temperature is 80°F. What is the maximum non-condensable pressure that can be present in the recovery cylinder before recovery must be stopped or adjusted?
- A50 psig
- B10 psig
- C0 psig
- D20 psig
Show answer & explanationAnswer & explanation
Correct answer: B. 10 psig
EPA regulations require that recovery cylinders for high-pressure refrigerants, especially when containing non-condensables, must not exceed 10 psig above the saturated vapor pressure at the ambient temperature to ensure safe operation and efficient recovery. For R-410A at 80°F, the saturated vapor pressure is approximately 236 psig. Therefore, the maximum allowable pressure inside the cylinder would be 236 psig + 10 psig = 246 psig. The question asks for the maximum non-condensable pressure, which is the pressure above the saturated vapor pressure, thus 10 psig.
Why the other options are wrong
- A. 50 psig is too high and would indicate a significant amount of non-condensables, posing safety risks and hindering recovery efficiency.
- C. 0 psig is an ideal scenario for no non-condensables, but not a regulatory limit for stopping recovery.
- D. 20 psig is a common limit for some other applications but not the specific non-condensable limit for recovery cylinders.
Recovery Cylinder Non-Condensable Limit
For high-pressure refrigerants, recovery cylinders must not contain non-condensables that result in a pressure exceeding 10 psig above the saturated vapor pressure of the refrigerant at the ambient temperature.
- Applies to high-pressure refrigerants.
- Limit is 10 psig above saturated vapor pressure.
- Ensures safe operation and efficient recovery.
Memory trick: Ten pounds is the safe non-condensable 'cap' for high-pressure recovery.