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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.

Value Unit of Pressure
Conversion value (Reference value)
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.

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