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[1] Vacuum pump with a check valve (See photo 1)
A vacuum pump with a check valve is required to prevent the vacuum pump oil from flowing back into the
refrigerant circuit when the power supply is cut off unexpectedly due to power outage.
A check valve may be added to a vacuum pump that is not equipped with one.
[2] Standard degree of vacuum for the vacuum pump
Use a pump that does not exceed 65Pa after 5 minutes of operation. Be sure to use a vacuum pump that has
been properly maintained and oiled with specified oil. If the vacuum pump is not properly maintained, desired
degree of vacuum may not be achieved.
[3] Necessary Accuracy of the Vacuum Gauge
Use a vacuum gauge that can measure 650Pa and in the increments/decrements of 130Pa. Do not use gauge
manifolds that cannot measure a vacuum of 650Pa. (Recommended vacuum gauze shown in Photograph 2
above)
[4] Vacuuming time
Evacuate the equipment for one hour after reaching 650Pa. (Moisture in the air will be removed by a thorough
evacuation.)
After evacuating, leave the equipment for one hour and make sure that degree of vacuum does not rise higher
than 130Pa. Refer to section 6 “Special Vacuuming Method” if it exceeds 130Pa.
[5] How to Stop the Vacuum Pump
In order to prevent a backflow of the vacuum pump oil, open the relief valve on the vacuum pump or loosen the
charge hose to draw in air before stopping the operation. The same operating procedure should be followed
when using a vacuum pump with a check valve.
[6] Special Vacuuming Method
Water infiltration or leakage is suspected when the degree of vacuum does not go below 650Pa after running
the vacuum pump for more than 3 hours. Check for leakage and water infiltration.
If water infiltration is the suspected cause, break vacuum with nitrogen. Then, pressurize nitrogen gas to
0.05MPa and try evacuating again. Repeat the procedure until the degree of vacuum goes below 650Pa or
until the pressure stops rising.
Be sure to use nitrogen to break vacuum. (The use of oxygen may cause an explosion)
Photograph 1
Photograph 2
Photograph 1 Recommended Vacuum Gauge : ROBINAIR 14010 Thermistor Vacuum Gauge
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Vacuum Drying (Evacuating)
