5 Common Maintenance
5.1 Vacuum drying for the system
5.1.1 Selection requirement for the vaccum pump
Do not use different vacuum pump for vaccum-pumping for different refrigerant system
；
The final vacuum for the vacuum pump should reach -0.1Mpa;
The air discharge volume for the vacuum pump should reach 4L/S above;
The precision of vacuum pup should reach 0.02mmHg above;
The system vacuum pump for R410A must be with check valve.
5.1.2 Operation procedure and notices for Vacuum drying
(1) 1Operation procedure
a) Before vacuum-pumping, please confirm that the cut-off valve for gas pipe and liquid pipe is
at off status;
b) Use charging conduct pipe to connect the governing value and vacuum heat pump to the
detection joint of gas valve and liquid valve;
c) After vacuum-pumping for 4h, check whether the vacuum degree is reached to -0.1MPa or
above; If not, there may be gas leakage. Please perform the leakage inspection again. If
there’s no gas leakage, please vacuum pump for another 2h.
d) If the required vaccum degree can’t be satisfied after vacuum-pumping for two times, there
are water inside the pipeline. Please drain out the water by the method of vaccum damage.
The detailed method: charge 0.05MPa nitrogen into the pipeline, vacuum pump for 2h and
then keep the cacuum for 1h. If -0.1 MPa vaccum degree still can’t be reached, repeat this
operation unitl the water is drained out completely.
(2) After the vacuum pump is finished, turn off the valve of governing valve and stop vacuum pump
and keep it for 1h. Please confirm that the pressure of governing valve hasn’t been increased.
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