Refrigeration Tools-Vacuum pump and vacuum gauge
In order to perform a sufficient evacuation a good vacuum pump must be available.
For stationary, use a two-stage 20 m3/h vacuum pump can be recommended but for service a smaller two-stage 10 m3/h vacuum pump is better suited due to its lower weight.
A hermetic refrigeration compressor is not suitable for the purpose since it is not able to produce a sufficiently low pressure, and also a compressor used as a vacuum pump would be overheated and damaged.
The insulation resistance of the air is reduced at falling pressure, and therefore there electrical breakdown at the current lead-in or in the motor of the hermetic compressor will quickly occur.
The same vacuum pump may be used for all types of refrigerants provided that it is charged with Ester oil.
A flameproof vacuum pump must be used for refrigeration systems containing the flammable refrigerants R600a and R290.
There is no point in having a suitable vacuum pump available if the vacuum obtained cannot be measured. Therefore, it is strongly recommended to use an appropriate robust vacuum gauge able to measure pressure below 1 mbar.