EPA 608 General Knowledge: Cylinders, Oils, and Safe Refrigerant Handling

Working with refrigerants is more than just knowing the refrigeration cycle — it’s about handling cylinders correctly, using the right oils, and staying safe on the job. These are areas the EPA 608 Exam loves to test, and they’re equally vital in the field. Let’s break it all down.

Cylinder Types and Handling

There are three main cylinder categories you’ll see in the HVAC trade:

1. DOT-39 Cylinders (Disposable)

   • Common in residential work.

   • Must never be refilled — doing so carries the same $44,539 fine as venting refrigerant.

   • Equipped with a burst disk for safety. Must be empty and pressure-free before disposal.

   Image prompt: A labeled diagram of a disposable DOT-39 cylinder showing the burst disk.

2. Returnable Cylinders

   • Often owned by refrigerant suppliers.

   • Equipped with pressure relief valves. These must be positioned toward the vapor space.

   Image prompt: Industrial returnable refrigerant cylinders with valves and safety labeling.

3. Recovery Cylinders

   • Gray bottom, white top — the universal recovery cylinder color code.

   • Can only be filled to 80% capacity to allow for expansion.

   • Must be documented with refrigerant type, weight recovered, and recovery location.

   • EPA recommends pulling a 1,000-micron vacuum before reuse.

   • Never mix refrigerants — reclamation facilities will reject tanks with mixed charges.

   

System Oils and Their Role

Refrigerant systems need special lubricants to keep compressors and other moving parts running smoothly.

• Most modern residential systems use POE (polyolester) oils.

• Oils must be low hygroscopic — meaning they resist absorbing moisture. Moisture in oil turns acidic and causes compressor burnout.

• Other synthetics exist (like PAG oils in automotive), but POE dominates stationary residential cooling.

  Image prompt: Cross-section of a compressor showing oil lubrication and refrigerant flow.

Safe Handling of Refrigerants

Refrigerants can cause serious harm if mishandled. Here’s what every tech should follow:

• Personal Protective Equipment (PPE):Gloves and safety glasses are a must. Liquid refrigerant can cause frostbite burns.

• Ventilation:Refrigerants displace oxygen. A large release in a confined space can lead to asphyxiation. Always ventilate and vacate if needed.

• Fire Safety:Some refrigerants (especially HFOs) are A2L – mildly flammable.

  • Eliminate ignition sources.

  • Keep a Class B fire extinguisher nearby.

  • No smoking within 25 feet of refrigerants.

• Transport and Storage:

  • Use DOT-approved racks in vans.

  • Point relief valves toward vapor space.

  • Keep cylinders under 120°F (49°C).

  Image prompt: Technician in PPE handling a refrigerant cylinder, with safety signage and ventilation arrows shown.

Key Takeaways

• DOT-39 cylinders are disposable; recovery cylinders are reusable up to 80% capacity.

• POE oils dominate residential cooling systems; moisture contamination destroys compressors.

• Always wear PPE, ventilate leaks, and treat refrigerants as asphyxiants and flammables.

• Safe storage and transport keep both techs and refrigerants in compliance.