R744 (CO2)  Theory

R744 (CO2)  Theory


Course Synopsis:

This course is suitable for technicians who are already experienced in handling refrigerants such as HFCs and who have a good understanding of system operation but wish to gain a theoretical knowledge of R744 systems

In house or on your site

1 Day

Background to the use of natural refrigerants

  • Summary of long-term alternative refrigerants and their current applications (HCs, HFOs, R717, R744).
  • Key characteristics and advantages of R744.


Critical point and triple point

  • Explanation of critical point and triple point using the phase diagram and pressure enthalpy diagram.


R744 hazards

  • Asphyxiation. Pressure.
  • Trapped liquid.
  • Dry ice.
  • Freeze burns.
  • Cylinders


Working Safely with R744

  • Personal protective equipment.
  • R744 fixed leak detectors and alarms.
  • Connection / charging equipment.
  • How to prevent dry ice formation.
  • Safe cylinder handling, storage and transport.
  • Risk assessments – explanation and worked example.


R744 cascade systems

  • Outline of basic cascade system.
  • Component differences, including pipe work, compressors, cascade heat exchangers, expansion valves, evaporators, pressure relief valves.

R744 as a pumped secondary refrigerant

  • Outline of basic pumped secondary system.


Trans critical systems & Trans critical booster systems

  • Outline of typical trans critical system for HT applications.
  • Component differences.
  • Explanation of requirement for two stage compression on LT R744 applications.


Reducing leak potential and improving resilience

  • Potential leak points, including pressure relief valves venting.
  • Types of joint – brazed joints to be used.
  • Pressure testing for leak tightness.
  • Leak test regime.


Installation and commissioning & Service of R744 systems

  • Pipe working and insulation.
  • Pressure testing for strength and leak tightness.
  • Evacuation.
  • Charging.
  • Leak testing methods.
  • Venting