6.3 Required Levels of Evacuation

EPA 608 Technician Certification Exam

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1 Introduction to EPA 608 Certification

1.1 What EPA 608 Is and Who Needs It 1.2 Exam Format, Scoring, and Administration 1.3 How to Study for EPA 608

2 Regulations and the Clean Air Act

2.1 Clean Air Act Overview 2.2 Penalties and Enforcement 2.3 Montreal Protocol and International Agreements 2.4 AIM Act and HFC Phasedown Schedule 2.5 SNAP Program and Refrigerant Transitions

3 Refrigerants and Ozone Science

3.1 The Science of Ozone Depletion (ODP and GWP) 3.2 Refrigerant Classification, ASHRAE Numbering, and Safety Groups 3.3 Common Refrigerants: Properties, Applications, and Phaseout Status 3.4 Refrigerant Blends: Glide, Fractionation, and Liquid Charging

4 The Refrigeration Cycle

4.1 The Basic Refrigeration Cycle 4.2 System Components in Detail 4.3 Heat Transfer and Pressure-Temperature Relationships

5 Refrigerant Safety and Handling

5.1 Refrigerant Hazards and Health Effects 5.2 Safe Handling Practices, PPE, and Cylinders 5.3 A2L (Mildly Flammable) Refrigerant Safety

6 Recovery, Recycling, and Reclaiming

6.1 The Three Rs: Recover, Recycle, Reclaim 6.2 Recovery Equipment Requirements 6.3 Required Levels of Evacuation 6.4 Refrigerant Sales Restrictions and Recordkeeping

7 Leak Detection and Repair

7.1 Leak Detection Methods 7.2 Leak Repair Requirements and Trigger Rates 7.3 Leak-Rate Calculation, Recordkeeping, and Reporting

8 Type I — Small Appliances

8.1 What Counts as a Small Appliance 8.2 Type I Recovery Requirements 8.3 Type I Procedures, Access Valves, and the Open-Book Exam

9 Type II — High-Pressure Appliances

9.1 What Type II Covers: High-Pressure System Overview 9.2 Type II Recovery Methods and Required Evacuation Levels 9.3 Leak Detection, the Repair Triggers, and Recordkeeping 9.4 The R-22 Phaseout, Retrofits, and the Move to Lower-GWP A2Ls

10 Type III — Low-Pressure Appliances

10.1 Low-Pressure System Fundamentals 10.2 Purge Units and Air Management 10.3 Type III Recovery and Procedures 10.4 Type III Leak Testing

11 10. Disposal, Shipping, and Compliance

11.1 Equipment Disposal Requirements 11.2 Refrigerant Shipping and Transport 11.3 Compliance Checklist and Best Practices

12 Final Review and Exam Strategy

12.1 High-Yield Core Section Review 12.2 Type I vs Type II vs Type III: Side-by-Side Review 12.3 How the Exam Works and Exam-Day Strategy

6.3 Required Levels of Evacuation

Key Takeaways Explain This Topic AI

Required evacuation depth depends on the appliance pressure class, the charge size (under vs. 200 lb or more), and whether equipment was made before or on/after November 15, 1993

For post-1993 equipment: very high-pressure and high-pressure under 200 lb = 0 psig; high-pressure 200 lb+ and medium-pressure under 200 lb = 10 in. Hg; medium-pressure 200 lb+ = 15 in. Hg

Low-pressure appliances require 25 mm Hg absolute regardless of charge size or equipment age

Pre-1993 equipment caps at 4 in. Hg for the larger high/medium-pressure systems instead of 10 or 15 in. Hg

If the required level cannot be reached, evacuate to the lowest level without contaminating the refrigerant, and never discharge above 0 psig before opening

Last updated: October 2026

Evacuation: How Deep You Must Pull the Vacuum

Recovering refrigerant is not just "get most of it out." Before a system is opened for service, repair, or disposal, the technician must pull it down to a specific, legally required level of evacuation , measured in inches of mercury vacuum (in. Hg) for higher-pressure systems or millimeters of mercury absolute (mm Hg absolute) for low-pressure systems. EPA publishes these targets in Table 1 — Required Levels of Evacuation for Appliances (40 CFR 82.156), and reproducing it from memory is one of the most valuable things you can do for the exam. Multiple questions across Core, Type II, and Type III draw directly from this table.

The required depth depends on three variables : (1) the appliance pressure class (very high, high, medium, or low pressure), (2) the charge size (under 200 lb vs. 200 lb or more), and (3) whether the recovery equipment was made before or on/after November 15, 1993 . Newer equipment must reach deeper vacuums because it is capable of doing so.

Why a Deeper Vacuum?

Pulling a deeper vacuum does two jobs at once: it satisfies federal law by removing essentially all the refrigerant, and it removes moisture and non-condensable gases that would otherwise corrode the system and form acids. So the evacuation requirement protects the planet and the equipment.

Table 1 (40 CFR 82.156) — Recovery Equipment Made ON OR AFTER November 15, 1993

Appliance Type Charge Size Required Evacuation
Very high-pressure (e.g., R-13, R-503) Any 0 in. Hg (0 psig)
High-pressure (e.g., R-22, R-407C, R-410A) < 200 lb 0 in. Hg (0 psig)
High-pressure ≥ 200 lb 10 in. Hg vacuum
Medium-pressure (e.g., R-114) < 200 lb 10 in. Hg vacuum
Medium-pressure ≥ 200 lb 15 in. Hg vacuum
Low-pressure (e.g., R-11, R-123) Any 25 mm Hg absolute
Table 1 (40 CFR 82.156) — Recovery Equipment Made BEFORE November 15, 1993

Appliance Type Charge Size Required Evacuation
Very high-pressure Any 0 in. Hg (0 psig)
High-pressure < 200 lb 0 in. Hg (0 psig)
High-pressure ≥ 200 lb 4 in. Hg vacuum
Medium-pressure < 200 lb 4 in. Hg vacuum
Medium-pressure ≥ 200 lb 4 in. Hg vacuum
Low-pressure Any 25 mm Hg absolute

Reading the Table the Way the Exam Tests It

Notice the pattern. For older (pre-1993) equipment the deeper requirement caps out at 4 in. Hg for the larger high/medium-pressure systems. For newer (post-1993) equipment those same large systems must be pulled to 10 in. Hg (high-pressure ≥ 200 lb and medium-pressure < 200 lb) or 15 in. Hg (medium-pressure ≥ 200 lb). The four numbers worth burning into memory for new equipment are therefore 0, 10, 15, and 25 mm Hg absolute .

Special Rules by Pressure Class

Very high-pressure appliances (which operate far above atmospheric) are evacuated only to 0 psig — you may not vent them above atmospheric pressure, but no deep vacuum is required.

Low-pressure appliances (which normally operate below atmospheric) require a true deep vacuum of 25 mm Hg absolute with recovery equipment of any age — a very low absolute pressure — because that is how you confirm essentially all the low-pressure refrigerant is out.

When You Cannot Reach the Required Level

Sometimes a leak or equipment limitation makes the table value unreachable. EPA provides a fallback procedure:

Isolate the leak if it is possible to do so.

Evacuate the appliance to the lowest level achievable without substantially contaminating the refrigerant .

You may never discharge refrigerant above 0 psig before opening the system, regardless of pressure class.

A related point: when an appliance is disposed of , the same recovery/evacuation requirements apply, and the last person in the disposal chain is responsible for ensuring recovery was completed.

Putting It Together

Example: A technician services a 300-pound R-22 (high-pressure) chiller using a recovery machine manufactured in 2019. Step 1 — confirm the pressure class: R-22 is high-pressure . Step 2 — check the charge: 300 lb is ≥ 200 lb . Step 3 — the equipment is post-1993. Reading Table 1, the required evacuation is 10 in. Hg vacuum . If the technician instead pulled only to 0 psig, the system would not be legally evacuated, because high-pressure systems of 200 lb or more on new equipment must reach 10 in. Hg.

Contrast Example: The same technician next services an R-11 low-pressure centrifugal chiller . Pressure class is low-pressure , so charge size is irrelevant — the requirement is 25 mm Hg absolute , a deep vacuum, with that post-1993 machine.

For the Exam: Memorize the post-1993 set — very high-pressure and small high-pressure: 0 psig ; high-pressure ≥ 200 lb and medium-pressure < 200 lb: 10 in. Hg ; medium-pressure ≥ 200 lb: 15 in. Hg ; low-pressure: 25 mm Hg absolute . And remember the dividing line is November 15, 1993 .