Controlling Liquid Refrigerant in A/C

In this podcast episode, Bryan and Trevor Matthews of Emerson Canada discuss strategies for controlling liquid refrigerant in A/C and refrigeration systems. They also read through the AE22-1182 bulletin, which you can find HERE.

Liquid refrigerant is one of the most common causes of compressor damage and even failure. It can also cause a loss of oil, which leads to reduced lubrication and subsequent damage. Compressors are vapor pumps, and they are not designed to handle much liquid refrigerant at all.

Off-cycle refrigerant migration is one of the main causes of liquid refrigerant reaching the compressor. Controlling liquid refrigerant in the off cycle is important because oil can also saturate that liquid refrigerant inside that compressor. That can cause a severe problem when the compressor starts up again. However, crankcase heaters can keep refrigerant migration at bay, as the refrigerant will be less likely to migrate and condense inside the compressor.

Liquid line solenoid valves and pump down cycles prevent refrigerant from going into the evaporator during the off cycle. During a pump down cycle, the compressor pumps all the liquid refrigerant into the condenser and receiver. If anything leaks past the solenoid, the compressor keeps pumping the liquid out. It's also best practice to use a crankcase heater if you use a one-time pump down.

Trevor and Bryan also discuss:

  • How to navigate Copeland bulletins
  • Oil miscibility with refrigerant vapor
  • Oil viscosity and its effect on oil return
  • Tripping oil pressure safeties
  • Crankshafts and bearing wear
  • Slugging vs. flood back
  • Minimizing refrigerant charge
  • Continuous vs. one-time pump down
  • Compressor temperature and its effect on liquid refrigerant control
  • Accumulators
  • Overheating or carbonizing oil with crankcase heaters
  • Oil separators

Learn more about Refrigeration Technologies HERE.

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