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What is "Vacuum"?
About "Vacuum"?
The Japanese Industrial Standards (JIS) defines a vacuum as "a state of space filled with gas whose pressure is lower than atmospheric pressure, not the pressure itself."
Lower than atmospheric pressure means "Vacuum".
Applicable condition of vacuum and suitable pressure range are as followings.
Unit of Pressure
Unit for pressure consist of Pa (pascal), N/m2 (square meter per newton), and bar, which are used as measurement unit of the SI, while non-SI unit used include torr and mmHg (millimeter of mercury column).
As either absolute pressure or gauge pressure is used for indicating vacuum pressure, it is necessary to check which format is used to indicate the pressure.
1.An absolute vacuum has an absolute pressure of zero ("0")"a" or "abs" is indicated after the unit2.The atmospheric pressure has a gauge pressure of zero ("0")"G" or "Gauge" is indicated after the unit
Atmospheric pressure value at each pressure unit
～In the case of absolute pressure display
| Unit | Atmospheric pressure | Absolute vacuum | Notes |
|---|---|---|---|
| Pa | 101325 | 0 | Pa＝N/m² |
| kPa | 101.3 | 0 | |
| MPa | 0.101 | 0 | |
| bar | 1.013 | 0 | |
| mbar | 1013 | 0 | |
| Torr | 760 | 0 | Torr＝mmHg |
| mmH2O | 10332 | 0 | |
| atm | 1 | 0 | |
| psi | 14.696 | 0 | |
| kgf/cm² | 1.0332 | 0 |
Atmospheric pressure value at each pressure unit
～In the case of gauge pressure display
| Unit | Atmospheric pressure | Absolute vacuum | Notes |
|---|---|---|---|
| Pa | 0 | -101325 | Pa＝N/m² |
| kPa | 0 | -101.3 | |
| MPa | 0 | -0.101 | |
| bar | 0 | -1.013 | |
| mbar | 0 | -1013 | |
| Torr | 0 | -760 | Torr＝mmHg |
| mmH2O | 0 | -10342 | |
| atm | 0 | -1 | |
| psi | 0 | -14.696 | |
| kgf/cm² | 0 | -1.0332 |
Unit conversion table
| Pa (N/m²) | Torr (mmHg) | atm | mbar | psi (bf/in²) | kgf/cm² | |
|---|---|---|---|---|---|---|
| 1MPa | 1,000,000 | 7500.63 | 1.019×10^5 | 10,000 | 145 | 10.19 |
| 1 Pa (N/m²) | 1 | 7.50×10-3 | 9.87×10-6 | 1×10-2 | 1.45×10-4 | 1.02×10-5 |
| 1 Torr (mmHg) | 133.32 | 1 | 1.316×10-3 | 1.33 | 1.93×10-2 | 1.359×10-2 |
| 1 atm | 1.013×105 | 760 | 1 | 1.013×103 | 14.696 | 1.033 |
| 1 mbar | 100 | 0.75 | 9.87×10-4 | 1 | 14.5×10-2 | 1.02×10-3 |
| 1 psi | 6.89×103 | 51.71 | 6.8×10-2 | 68.9 | 1 | 7.031×10-2 |
| 1 kgf/cm² | 9.8×104 | 735.56 | 0.968 | 9.81×102 | 14.223 | 1 |
Pressure conversion
The specified unit of pressure is converted into a different unit.
Input the pressure with half-width and select the unit.
| Pa (N/m²) | |
| MPa | |
| Torr (mmHg) | |
| atm | |
| bar | |
| mbar | |
| psi (bf/in²) | |
| kgf/cm² |
Leakage volume of ball valve at vacuum condition
Please inquire with HISAKA for information about the leakage volume at vacuum condition of HISAKA ball valves.
We suggest a leakage colume of approximately 1 torr for valve internal pressure of 133 Pa.
