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Vacuum drying works
Degree of vacuum must be within the range expressed by
0 Torr
0 Pa
760 mmHg
Perfect vacuum
5 Torr
667 Pa
755 cmHg
Vacuum target value
2) Vacuum pump maintenance
Because of their nature, most vacuum pumps contain large
amounts of oil which lubricates bearings, etc., and functions
to enhance airtightness of pistons. When using a vacuum
pump to discharge air from refrigerant piping, moisture in
the air tends to get mixed in with the oil. You must therefore
change oil periodically and make sure the proper oil level is
maintained. (Perform periodic inspections in accordance
with the operating instructions.)
3) Degree of vacuum measurement
An extremely accurate vacuum gauge is required to test
degree of vacuum. You cannot accurately measure degree
of vacuum with the compound gauge on the gauge manifold.
A Pirani vacuum gauge is required to measure degree
of vacuum accurately. Because Pirani gauges are very sensitive
and require extreme care when using, they are not
very suitable for use in the field. You should therefore use
the Pirani gauge to calibrate the attached vacuum gauge on
the gauge manifold and the degree of vacuum of the vacuum
pump.
4) Calibration method
1. Connect a Pirani vacuum gauge and the gauge manifold
vacuum gauge (760 mmHg) to the vacuum pump at the
same time, and run the pump for about 3 minutes.
2. Make sure the reading of the Pirani vacuum gauge is 5
Torr (667 Pa ) or less. The reading of conventional vacuum
pumps lowers to about 0.2 Torr.
If the reading is not 5 Torr or less, check the vacuum
pump oil. (Oil is low in many cases.)
3. Check the attached gauge on the gauge manifold. Adjust
the gauge if the reading is not exactly correct.
4. Adjust the gauge manifold valve so that the Pirani vacuum
gauge reads 5 Torr.
5. Mark the position indicated by the gauge manifold gauge
with an oil based ink pen.
6. Use the mark of the gauge manifold as a target when
vacuuming in the field.
Pressure detection section
Indicator
5CSL0-06B
760 Torr
1013.33 hPa
0 mmHg
Standard atmospheric pressure
Gauge manifold
(Reference) Types of vacuum pump with respect to maximum
degree of vacuum
Vacuum pump
Many handy
pumps fall into this
category
314 Guideline for each installation process
Type
Oil rotary
(Oil using)
Oilless rotary
(No need of oil)
Maximum degree of vacuum Use
Expulsion capacity Vacuum drying Air expulsion
0.02 mmHg
100 l/min Suitable Suitable
10 mmHg
0.02 mmHg
50 l/min
40 l/min
Unsuitable
Suitable
Suitable
Suitable