Question 1Evacuation levels
A technician recovers from a 120 lb R-22 system with a recovery machine made in 1992 before replacing the compressor. What level is required?
Required evacuation levels
Pick the appliance, the job and when the recovery machine was made, and get the level the rule requires before the appliance is opened or scrapped, with the reason.
Find the required level
High-pressure (R-22)
10 inches of mercury vacuum
Before a major repair, a high-pressure appliance with a full charge of 200 pounds or more must reach 10 inches of mercury vacuum when the recovery equipment was made on or after 15 November 1993.
Verify the level is reached before the appliance is opened.
The table for major repairs and disposal
| Appliance | Equipment before 15 Nov 1993 | On or after 15 Nov 1993 |
|---|---|---|
| Very high-pressure | 0 in Hg vacuum | 0 in Hg vacuum |
| High-pressure, under 200 lb | 0 in Hg vacuum | 0 in Hg vacuum |
| High-pressure, 200 lb or more | 4 in Hg vacuum | 10 in Hg vacuum |
| Medium-pressure, under 200 lb | 4 in Hg vacuum | 10 in Hg vacuum |
| Medium-pressure, 200 lb or more | 4 in Hg vacuum | 15 in Hg vacuum |
| Low-pressure | 25 mm Hg absolute | 25 mm Hg absolute |
Small appliances, motor vehicle air conditioners and similar appliances follow their own rules.
Pressure classes
| Class | Saturated liquid at 104 F | Examples |
|---|---|---|
| Low-pressure | Saturated liquid below 45 psia at 104 F | R-11, R-123, R-113, R-245fa |
| Medium-pressure | 45 to 170 psia at 104 F | R-114, R-124, R-12, R-134a, R-500 |
| High-pressure | 170 to 355 psia at 104 F | R-22, R-407A, R-407C, R-410A, R-502 |
| Very high-pressure | A critical temperature below 104 F, or above 355 psia at 104 F | R-13, R-23, R-503, R-508A, R-508B |
Try 3 test questions
Question 2Evacuation levels
A lab's ultra-low-temperature system uses R-23, a very high-pressure refrigerant. Before a major repair, what level must it reach with a new recovery machine?
Question 3Small appliance recovery rules
A freezer's nameplate lists a 20-ounce charge. Its compressor will not run, and the recovery equipment was made in 2010. What is the least the technician may recover?
Next step
Questions people ask
What vacuum is required before opening an R-22 system?
R-22 is a high-pressure refrigerant. With recovery equipment made on or after 15 November 1993, a system under 200 pounds goes to 0 inches of mercury vacuum and one of 200 pounds or more to 10 inches, before a major repair or disposal.
What about a repair that is not major?
If no evacuation is planned afterwards, medium-, high- and very high-pressure appliances go to no higher than 0 psig, and low-pressure appliances are pressurized to no higher than 0 psig. An oil change allows up to 5 psig.
How much must be recovered from a small appliance?
With recovery equipment made on or after 15 November 1993: 90 percent if the appliance's compressor works, 80 percent if it does not. With older equipment, 80 percent. Reaching 4 inches of mercury vacuum also meets the rule.
What counts as a major repair?
Removing the compressor, condenser, evaporator or an auxiliary heat exchange coil, or uncovering an opening of more than 4 square inches of flow area for more than 15 minutes.