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EPA 608 Technician Certification: High-Pressure Recovery Requirements and Techniques Concepts

Importance ★★★★★ · 40% (estimate)

Overview

This chapter covers how far high- and medium-pressure appliances must be evacuated before they are opened, and how to recover refrigerant quickly and cleanly. The required level depends on the appliance's pressure class, whether the charge is under or over 200 pounds, and when the recovery equipment was made.

With recovery equipment made on or after November 15, 1993, a high-pressure appliance under 200 pounds must reach 0 inches of mercury, and one with 200 pounds or more must reach 10 inches of mercury vacuum. Medium-pressure appliances need 10 inches under 200 pounds and 15 inches at 200 pounds or more. With older equipment, the levels are 0 or 4 inches. Very high-pressure appliances need 0 inches.

A non-major repair that is not followed by evacuation to the air needs only 0 psig, and an oil change needs 5 psig or less. A major repair removes the compressor, condenser, evaporator, or auxiliary heat exchange coil, or leaves an opening of more than 4 square inches open for more than 15 minutes. If leaks prevent reaching the level, isolate leaking parts and evacuate them as low as possible, no higher than 0 psig.

Recover liquid first, chill the recovery cylinder, or warm the appliance to speed recovery. After reaching the level, wait a few minutes; a pressure rise means refrigerant is still there. System-dependent equipment may not be used on appliances over 15 pounds. Clear the machine and change the filter before switching refrigerants.

Key concepts

  • Evacuation table

    The required level before opening or disposal depends on pressure class, charge size (under or over 200 lb), and whether the recovery equipment was made before or after November 15, 1993.

    Memory tipClass, size, machine date.

    Source: 40 CFR 82.156 Table 1 (EPA Section 608 rules) · as of 2026

  • Major repair

    Removing the compressor, condenser, evaporator, or auxiliary heat exchange coil, or uncovering an opening of more than 4 square inches of flow area for more than 15 minutes.

    Memory tipBig parts out = major.

    Source: 40 CFR 82.152 (EPA Section 608 rules) · as of 2026

  • Non-major repair level

    If a repair is not major and is not followed by evacuation to the air, medium-, high-, and very high-pressure appliances need only be evacuated to 0 psig.

    Memory tipNon-major: 0 psig.

    Source: 40 CFR 82.156(a)(1) (EPA Section 608 rules) · as of 2026

  • Leaky system rule

    If leaks prevent reaching the required level, isolate leaking parts, evacuate non-leaking parts normally, and evacuate leaking parts as low as possible, no higher than 0 psig.

    Memory tipLeaking: as low as you can, max 0 psig.

    Source: 40 CFR 82.156(a)(2) (EPA Section 608 rules) · as of 2026

  • Oil change level

    Before opening for an oil change, the appliance or the isolated oil must be at no higher than 5 psig.

    Memory tipOil change: 5 psig.

    Source: 40 CFR 82.156(a)(1)(iii) (EPA Section 608 rules) · as of 2026

  • Speeding recovery

    Recover liquid first, chill the recovery cylinder, or heat the appliance (never with a flame) to raise the pressure difference.

    Memory tipLiquid first; cold cylinder, warm system.

    Source: EPA Section 608 Test Topics · as of 2025

Often tested

  • Wait a few minutes after reaching the level; a pressure rise means refrigerant remains.
  • System-dependent recovery: not over 15 pounds.
  • You may evacuate only an isolated part if its refrigerant is held in the receiver.
  • Clear the recovery machine and change the filter between refrigerants.

Easy to confuse: Evacuation levels (inches of Hg vacuum)

ApplianceEquipment before Nov. 15, 1993Equipment on or after Nov. 15, 1993
Very high-pressure00
High-pressure, under 200 lb00
High-pressure, 200 lb or more410
Medium-pressure, under 200 lb410
Medium-pressure, 200 lb or more415
Low-pressure25 mm Hg absolute25 mm Hg absolute

3 sample questions

Verified practice questions from this unit.

Practice questionReviewedType II (High-Pressure) › High-Pressure Recovery Requirements and Techniques★★★★★

Question 1. A high-pressure appliance holds 50 pounds of R-410A. Using recovery equipment made after November 15, 1993, to what level must it be evacuated before opening?

  1. ① 15 inches of mercury vacuum
  2. ② 25 mm Hg absolute
  3. ③ 0 inches of mercury (0 psig)
  4. ④ 10 inches of mercury vacuum
▼ Show answer and explanation▲ Hide answer and explanation

Answer: ③ 0 inches of mercury (0 psig)

Key point: High-pressure under 200 lb: 0 in. Hg

Table 1 in 40 CFR 82.156 requires 0 inches of mercury for a high-pressure appliance under 200 pounds, with either older or newer recovery equipment. With 200 pounds or more and newer equipment, the level is 10 inches.

Wrong choices

  • 15 inches of mercury vacuum: 15 inches applies to medium-pressure appliances with 200 pounds or more.
  • 25 mm Hg absolute: 25 mm Hg absolute applies to low-pressure appliances.
  • 10 inches of mercury vacuum: 10 inches applies to high-pressure appliances with 200 pounds or more.
Practice questionReviewedType II (High-Pressure) › High-Pressure Recovery Requirements and Techniques★★★★★

Question 2. How can a technician speed up recovery from a high-pressure system that has a lot of liquid refrigerant?

  1. ① Warm the recovery cylinder
  2. ② Recover vapor first and liquid last
  3. ③ Use longer hoses
  4. ④ Recover liquid refrigerant first
▼ Show answer and explanation▲ Hide answer and explanation

Answer: ④ Recover liquid refrigerant first

Key point: Recover liquid first to speed recovery

Removing liquid first moves most of the refrigerant much faster than removing it as vapor. After the liquid is out, recover the remaining vapor.

Wrong choices

  • Warm the recovery cylinder: Warming the recovery cylinder raises its pressure and slows recovery.
  • Recover vapor first and liquid last: Recovering only vapor first is slower when there is a lot of liquid.
  • Use longer hoses: Longer hoses add restriction and slow recovery.
Practice questionReviewedType II (High-Pressure) › High-Pressure Recovery Requirements and Techniques★★★★★

Question 3. A high-pressure appliance holds 300 pounds of R-22. Using recovery equipment made after November 15, 1993, to what level must it be evacuated?

  1. ① 4 inches of mercury vacuum
  2. ② 15 inches of mercury vacuum
  3. ③ 10 inches of mercury vacuum
  4. ④ 0 inches of mercury
▼ Show answer and explanation▲ Hide answer and explanation

Answer: ③ 10 inches of mercury vacuum

Key point: High-pressure 200 lb+, new equipment: 10 in. Hg

For a high-pressure appliance with 200 pounds or more, Table 1 requires 10 inches of mercury vacuum with recovery equipment made on or after November 15, 1993 (4 inches with older equipment).

Wrong choices

  • 4 inches of mercury vacuum: 4 inches applies when using equipment made before November 15, 1993.
  • 15 inches of mercury vacuum: 15 inches applies to medium-pressure appliances with 200 pounds or more.
  • 0 inches of mercury: 0 inches applies when the charge is under 200 pounds.
Practice 5 questions from this unit →

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