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EPA 608 Technician Certification: High-Pressure Systems, Refrigerants, and Safety Concepts

Importance ★★★☆☆ · 25% (estimate)

Overview

This chapter covers the equipment and refrigerants Type II technicians work with and the safety points that go with them. It explains the pressure classes, the main system parts and the refrigerant state in each, how to identify a refrigerant, and why some actions can damage equipment.

EPA classes appliances by the refrigerant's liquid saturation pressure at 104°F. High-pressure refrigerants (170 to 355 psia) include R-22, R-407C, and R-410A. Medium-pressure (45 to 170 psia) includes R-134a and R-12. Very high-pressure includes R-23 and R-13. Type II covers all three of these classes.

The receiver stores high-pressure liquid after the condenser. The accumulator in the suction line keeps liquid away from the compressor. The suction line carries low-pressure vapor and the discharge line carries high-pressure vapor. Read the nameplate to identify the refrigerant, and add 14.7 to a gauge reading before using a PT chart in psia.

Never start a hermetic compressor while the system is in a deep vacuum, because the motor windings can be damaged. Hydrocarbons are not approved for retrofitting these systems. Under ASHRAE Standard 15, equipment rooms need a refrigerant or oxygen-deprivation sensor with an alarm.

Key concepts

  • High-pressure appliance

    An appliance using a refrigerant with a liquid saturation pressure between 170 and 355 psia at 104°F, such as R-22, R-407A, R-407C, R-410A, and R-502.

    Memory tipR-22 and R-410A = high.

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

  • Medium-pressure appliance

    An appliance using a refrigerant with a liquid saturation pressure between 45 and 170 psia at 104°F, such as R-12, R-114, R-124, R-134a, and R-500.

    Memory tipR-134a = medium (Type II).

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

  • Very high-pressure appliance

    An appliance using a refrigerant with a critical temperature below 104°F or a liquid saturation pressure above 355 psia at 104°F, such as R-13, R-23, and R-503.

    Memory tipR-23, R-13 = very high.

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

  • Receiver

    A tank on the high side, after the condenser, that stores high-pressure liquid refrigerant.

    Memory tipReceiver = liquid storage.

  • Accumulator

    A tank in the suction line that traps liquid refrigerant so only vapor reaches the compressor.

    Memory tipAccumulator protects the compressor.

  • Hermetic compressor under vacuum

    A hermetic compressor should never be energized while the system is in a deep vacuum, because the motor windings can be damaged.

    Memory tipNo power under vacuum.

    Source: EPA Section 608 Test Topics · as of 2025

Often tested

  • Identify the refrigerant from the nameplate.
  • psia = psig + 14.7 when using a PT chart in absolute pressure.
  • Hydrocarbons are not approved for retrofits.
  • ASHRAE 15 equipment rooms need a refrigerant or oxygen-deprivation sensor.

3 sample questions

Verified practice questions from this unit.

Practice questionReviewedType II (High-Pressure) › High-Pressure Systems, Refrigerants, and Safety★★★☆☆

Question 1. Which refrigerant is classified as a high-pressure refrigerant?

  1. ① R-11
  2. ② R-123
  3. ③ R-134a
  4. ④ R-410A
▼ Show answer and explanation▲ Hide answer and explanation

Answer: ④ R-410A

Key point: R-22, R-410A, R-407C = high-pressure

40 CFR 82.152 defines a high-pressure appliance as one using a refrigerant with a liquid saturation pressure between 170 and 355 psia at 104°F. Examples are R-22, R-407A, R-407C, R-410A, and R-502.

Wrong choices

  • R-11: R-11 is a low-pressure refrigerant.
  • R-123: R-123 is a low-pressure refrigerant.
  • R-134a: R-134a is a medium-pressure refrigerant (still covered by Type II).
Practice questionReviewedType II (High-Pressure) › High-Pressure Systems, Refrigerants, and Safety★★★☆☆

Question 2. What is the job of the receiver in a high-pressure refrigeration system?

  1. ① To absorb heat from the space
  2. ② To remove air from the system
  3. ③ To compress vapor
  4. ④ To store liquid refrigerant
▼ Show answer and explanation▲ Hide answer and explanation

Answer: ④ To store liquid refrigerant

Key point: Receiver stores high-pressure liquid

The receiver sits after the condenser on the high side and stores liquid refrigerant. The refrigerant in it is a high-pressure liquid, which is why refrigerant can be pumped down into the receiver to isolate it.

Wrong choices

  • To absorb heat from the space: Absorbing heat is the evaporator's job.
  • To remove air from the system: Removing air is done by evacuation or a purge unit.
  • To compress vapor: Compressing vapor is the compressor's job.
Practice questionReviewedType II (High-Pressure) › High-Pressure Systems, Refrigerants, and Safety★★★☆☆

Question 3. What is the best way to identify the refrigerant in a high-pressure appliance before recovering it?

  1. ① Look at the color of the refrigerant lines
  2. ② Smell the refrigerant
  3. ③ Read the nameplate on the appliance
  4. ④ Ask the building owner to guess
▼ Show answer and explanation▲ Hide answer and explanation

Answer: ③ Read the nameplate on the appliance

Key point: Nameplate shows the refrigerant type

The appliance nameplate lists the refrigerant type and charge. A pressure and temperature check with a PT chart can confirm it.

Wrong choices

  • Look at the color of the refrigerant lines: Line color does not identify the refrigerant.
  • Smell the refrigerant: Smelling refrigerant is unsafe and does not identify it.
  • Ask the building owner to guess: A guess is not reliable.
Practice 5 questions from this unit →

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