Water content of R290 and R1270

• R290 and R1270 of a high degree of purity do not contain any elements that tend to form acids. However, a high moisture content should be avoided.
• Consequences:
• Risk of crystal formation in expansion devices.
• At high pressure and low temperature: Formation of gas hydrates in the liquid that may clog up narrow passages in the system.
• Measures:
• Use a refrigerant containing only little non condensable gases and no additives.
• Use a high propane or propene grade ("2.5" or comparable) having a purity of 99.5 % (Requirements for hydrocarbons according to DIN 8960:1998).
• Avoid entry of non condensable gases and moisture.
• Install a generously sized drier – design and dimensions according to manufacturer’s specifications.
• Use moisture indicators with defined display of the degree of drying (< 50 ppm).
• For tightness tests and high-pressure tests, use preferably dried nitrogen. When testing with dried air, the compressor must not be included (keep shut-off valves closed!).
• Use two-stage vacuum pumps with gas ballast (1.5 mbar “standing vacuum”) to avoid condensation of water vapour. Use large connection dimensions.
• Keep compressor shut-off valves closed until the last evacuation process!