Refrigerant Types and Handling

Blends, glide, safety classifications and why you never mix refrigerants or charge a blend as vapor.

Concept

Advanced

#refrigeration#refrigerant#safety#charging

Safety

Confirm the refrigerant and its safety classification before servicing. Never mix refrigerants, and follow the manufacturer instructions for flammable refrigerants.

What it is

Refrigerants are fluids selected for a boiling point range that suits the application. They differ in operating pressures, oil compatibility, flammability and environmental impact, and they are not interchangeable.

Azeotropic blend

A mixture that behaves as a single substance, boiling and condensing at one temperature for a given pressure.

Zeotropic blend

A mixture whose components boil at different temperatures, producing a temperature glide between the bubble point and the dew point.

Glide

The difference between the bubble point and dew point temperature at a given pressure. It changes how you calculate superheat and subcooling.

Why it matters

Charge zeotropic blends as liquid. Charging vapor removes the lighter components first and changes the composition of what is left in the cylinder and the system.
Use the dew point column for superheat and the bubble point column for subcooling.
Oil must match the refrigerant. Mineral oil does not circulate properly with most modern refrigerants, which use polyolester oil.
Mixing refrigerants makes the charge impossible to diagnose and the recovered material impossible to reclaim.

Know the safety classification

Some current refrigerants are classed as mildly flammable. They require specific leak detection equipment, charge limits, service procedures and sometimes different tooling. Follow the manufacturer instructions and the regulations that apply before working on any system you are not familiar with.

Working practice

1Identify the refrigerant from the equipment data plate, not from the colour of a cylinder.
2Confirm your gauges, hoses and recovery equipment are rated for that refrigerant and its pressures.
3Set a digital manifold to the correct refrigerant profile before taking readings.
4Charge blends as liquid, metered into the suction side using an approved method that protects the compressor.
5Weigh the charge and record it.

Never top up a mixed or unknown charge

If the refrigerant in a system cannot be confirmed, recover it as mixed refrigerant and start clean rather than adding to an unknown mixture.

Local requirements

Permitted refrigerants, charge limits, ventilation, storage and certification requirements vary by jurisdiction, adopted code edition and equipment listing.

Local Code Notice

Permitted refrigerants, charge limits, storage, ventilation and certification requirements vary by jurisdiction, adopted code edition and equipment listing.

Symptoms

Refrigerant leak
Background

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