Short Answer: EPA sets required evacuation levels in Table 1 of 40 CFR 82.156, based on pressure class, charge size and whether the recovery equipment was made before or after November 15, 1993.
Quick Facts
| Rule | 40 CFR 82.156(a), Table 1 |
|---|---|
| High-pressure, 200 lb+ (new equipment) | 10 in. Hg |
| Medium-pressure, 200 lb+ (new equipment) | 15 in. Hg |
| Low-pressure | 25 mm Hg absolute |
| Small appliances | 90% / 80% or 4 in. Hg |
Table 1: Appliances Other than Small Appliances
| Appliance | Equipment made before 15 Nov 1993 | Equipment made on or after 15 Nov 1993 |
|---|---|---|
| Very high-pressure | 0 in. Hg | 0 in. Hg |
| High-pressure, under 200 lb | 0 in. Hg | 0 in. Hg |
| High-pressure, 200 lb or more | 4 in. Hg | 10 in. Hg |
| Medium-pressure, under 200 lb | 4 in. Hg | 10 in. Hg |
| Medium-pressure, 200 lb or more | 4 in. Hg | 15 in. Hg |
| Low-pressure | 25 mm Hg absolute | 25 mm Hg absolute |
Vacuum is in inches of mercury relative to standard atmospheric pressure (29.9 in. Hg). Source: 40 CFR 82.156(a), Table 1.
Exceptions
- Non-major repairs not followed by evacuation: high- and medium-pressure appliances only need to reach 0 psig. Low-pressure appliances are pressurized to no more than 0 psig, using heat first where the refrigerant boils above 85 °F (82.156(a)(1)).
- Oil changes: no more than 5 psig.
- Leaky systems: evacuate non-leaking parts to Table 1 levels, and leaking parts to the lowest level possible without contaminating the refrigerant, never above 0 psig.
- Major repairs mean removing the compressor, condenser, evaporator or auxiliary heat-exchange coil, or uncovering more than 4 sq in of flow area for over 15 minutes.
Small Appliances (Type I)
| Recovery equipment | Compressor working | Compressor not working |
|---|---|---|
| Made before 15 Nov 1993 | 80% | 80% |
| Made on or after 15 Nov 1993 | 90% | 80% |
Or evacuate to 4 in. Hg vacuum (82.156(b)). System-dependent equipment can't be used on appliances holding more than 15 lb, unless it is a permanently attached pump-out unit.
Disposal
The final processor (a scrap recycler or landfill) must recover any remaining refrigerant from small appliances, or get a signed statement giving the name and address of whoever recovered it and the date (82.155). From 2018, technicians who evacuate appliances holding 5–50 lb for disposal must keep records for three years.
Practise It
Why Evacuation Levels Exist
The required evacuation levels make sure most of the refrigerant is removed before a system is opened or thrown away. The deeper the vacuum, the less refrigerant is left behind to escape into the air. The levels depend on two things: how much refrigerant the appliance holds, and how old the recovery equipment is. Equipment made on or after 15 November 1993 must meet stricter levels because it was built to the newer certification standard.
Reading the Table
To use Table 1, first identify the appliance's pressure group from the refrigerant it uses. Low-pressure refrigerants have a saturation pressure below 45 psia at 104 °F, medium-pressure 45 to 170 psia, high-pressure 170 to 355 psia and very high-pressure above 355 psia. Then check the charge size: under 200 lb or 200 lb or more. Finally, check the date your recovery equipment was made. The intersection gives the required level.
Inches of mercury vacuum are measured below atmospheric pressure. A reading of 0 in. Hg is atmospheric pressure, and higher numbers are deeper vacuums. Low-pressure appliances use millimetres of mercury absolute, where lower numbers mean a deeper vacuum.
Recovery Techniques That Save Time
- Recover liquid first. Liquid moves much faster than vapour. On larger systems, removing liquid first can shorten the job considerably.
- Use short, wide hoses and remove valve cores where the equipment allows it, because restrictions slow recovery.
- Keep the recovery cylinder cool. A cooler cylinder has lower pressure, which helps the recovery machine move refrigerant.
- Watch for rising pressure after you reach the target vacuum. If the pressure climbs back up, refrigerant is still boiling out of oil or trapped liquid, and you should keep recovering.
Recovery Equipment Certification
Recovery and recycling equipment made on or after 15 November 1993 must be certified by an EPA-approved testing organisation to meet the standards in 40 CFR 82.158. Equipment intended for flammable refrigerants must meet the additional appendix standards for those refrigerants. Look for the certification label on the machine.
Evacuating After Repairs
Recovery removes refrigerant before service. After the repair, a vacuum pump removes air and moisture before the system is recharged. This dehydration step is about system performance and reliability, and a micron gauge gives the most accurate reading of how deep the vacuum is. Moisture left in a system can form acids and ice at the expansion device.
Exam Tips
- Know the post-1993 levels for each pressure group: 0, 10 and 15 in. Hg, plus 25 mm Hg absolute for low-pressure.
- The 200 lb charge size is the dividing line in Table 1.
- Small appliances use percentages (90% or 80%) or 4 in. Hg.
- System-dependent recovery is limited to appliances holding 15 lb or less.
Worked Examples
A rooftop unit with 25 lb of R-410A, using a recovery machine made in 2020. R-410A is a high-pressure refrigerant, the charge is under 200 lb and the equipment is newer, so the required level is 0 in. Hg.
A large R-22 system with 250 lb, using newer equipment. R-22 is a high-pressure refrigerant in the regulation's grouping, and the charge is over 200 lb, so the required level is 10 in. Hg.
A centrifugal chiller using R-123. R-123 is a low-pressure refrigerant, so the required level is 25 mm Hg absolute regardless of size.
A household fridge with a working compressor, using newer equipment. Recover 90% of the charge, or evacuate to 4 in. Hg.
Checking Your Recovery Machine's Date
The manufacture date is shown on the machine's label. If you can't find it, assume the stricter post-1993 levels apply. Most machines in use today were made well after 1993.
Key Terms
- Self-contained recovery equipment: has its own compressor and can remove refrigerant without help from the appliance.
- System-dependent recovery equipment: relies on the appliance's compressor or pressure. Allowed only on appliances holding 15 lb or less.
- Major repair: removing the compressor, condenser, evaporator or auxiliary heat-exchange coil, or opening a large flow area for an extended time.
- Non-major repair: any repair that is not a major repair, which allows a less stringent evacuation level when not followed by an evacuation.
- Final processor: the last person in the disposal chain, such as a scrap recycler or landfill operator.
Common Exam Traps
- Mixing up gauge vacuum (in. Hg) and absolute pressure (mm Hg absolute).
- Forgetting that older recovery equipment has less strict levels.
- Using system-dependent equipment on a system over 15 lb.
- Assuming small appliances use Table 1. They use percentages or 4 in. Hg.
On the Job
Before you start recovery, confirm the refrigerant from the nameplate, choose a clean and correctly labelled cylinder with enough capacity and check that your machine's filter is fresh. When you finish, record the amount recovered.
Quick Questions
Why Does a Deeper Vacuum Apply to Bigger Systems?
A larger charge leaves more refrigerant behind at any given pressure, so a deeper vacuum is needed to keep the remaining amount small.
Do I Have to Evacuate to Table 1 Levels for a Simple Valve Core Change?
Non-major repairs not followed by an evacuation allow a less stringent level: 0 psig for high- and medium-pressure appliances. Major repairs require the full Table 1 levels.
What if the System Has a Large Leak and Won't Hold a Vacuum?
Evacuate the non-leaking parts to the required level and the leaking parts to the lowest level that is achievable without contaminating the refrigerant, never above 0 psig.
Is a Micron Gauge Required for Recovery?
Recovery levels in Table 1 are stated in inches or millimetres of mercury. A micron gauge is mainly used for dehydration after repairs, where it gives a far more precise reading of deep vacuum.
Table 1 is heavily tested in Type II: try the EPA 608 Type II Practice Test: High-Pressure Systems and the EPA 608 Type I Practice Test: Small Appliances.
Where to Go Next
Steps to Take
- Identify the appliance's pressure class.
- Check its charge size against 200 lb.
- Check your recovery equipment's manufacture date.
- Read the required level from Table 1.
- Evacuate and record the job.
Frequently Asked Questions
What vacuum is required for a low-pressure appliance?
25 mm Hg absolute, whatever the recovery equipment's date (Table 1, 40 CFR 82.156).
Does recovery equipment need to be certified?
Yes. Recovery equipment made after November 15, 1993 must be certified by an EPA-approved testing organisation (40 CFR 82.158).
What if the system has a leak?
Evacuate the non-leaking parts to Table 1 levels and the leaking parts to the lowest level possible without drawing in air.