Refrigerant requirements and filling process
DANGER
Liquid R744 evaporates quickly, cools down at the same time and forms dry ice!
Danger of cold burns and frost bites!
Avoid uncontrolled deflating of R744!
When filling the system with R744, wear gloves and goggles!
- Use a pressure reducer when removing R744 from cylinders without a riser tube! In general, even after maintenance work, always break vacuum with gaseous R744.
- For R744 cylinders with riser tube, high pressure liquid removal only! Do not use a pressure reducer! Membranes of the pressure reducers are not completely sealed against liquid.
- After filling the system with liquid, remove the filling pipe or hose and make sure that no liquid is trapped in it!
Permitted refrigerant
R744 or CO2 of purity class N4.5 or comparable, or H2O < 5 ppm.
The CO2 purity class can contain a higher H2O content if a generously sized filter drier is used and the system is filled via this. It is recommended to change the filter drier several times after commissioning (chapter filter drier).
Due to the high requirements for residual moisture, CO2 of purity class N3.0 must always be filled via a filter drier!
Filling process
- Do not switch on the compressor.
- Switch on the oil heater.
- Do not start the filling process until the following oil temperature has been reached: min. toil = tamb + 20 K. Ideally at 35–40°C.
- Open the valves of the filling connections and break the vacuum with R744 from the gas phase of the filling cylinder up to an excess pressure of approx. 10 bar. If the refrigerant cylinder cools down considerably, heat in a water bath (water max. 40°C)!
From approx. 10 bar system pressure, ensure that the suction and discharge gas shut-off valves of the compressor(s) are closed.
For booster systems: Concerns the compressors of the medium and low temperature compressor stage.
Further filling and commissioning depend on the specific system design, see information in the chapters: