# Vacuum

The vacuum level is the difference in pressure between atmospheric pressure and pressure in the evacuated system:

*0% vacuum = 760 torr = 14.7 psia = 29.92 inc mercury abs = 101.4 kPa abs**50% vacuum = 380 torr = 7.3 psia = 15 inc mercury abs = 50.8 kPa abs**99.9% vacuum = 1 torr = 0.01934 psia = 0.03937 inc mercury abs = 1.3 kPa abs*

For perfect vacuum * (100%) * - the pressure is * 0 torr, 0 psia or 0 Pa abs. *

### Vacuum versus Absolute Air Pressure

* *

#### Example - Vacuum

If the absolute pressure is * 60 kPa * the vacuum according the diagram above is approximately * 40 % * - or approximately * 450 * Torr .

### Vacuum Ranges

- atmospheric pressure - 760 torr
- low vacuum -
*760 to 25 torr* - medium vacuum -
*25 to 10*^{ -3 }torr - high vacuum -
*10*^{ -3 }to 10^{-9}torr - ultra high vacuum -
*10*^{-9}to 10^{-12}torr - extremely high vacuum
*- < 10*^{-12}torr - perfect vacuum
*- 0 torr <*

## Related Topics

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## Related Documents

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Convert vacuum air volume to standard air volume

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Measure air volume flow in vacuum.

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Converting between vacuum units like % vacuum - mm Mercury - psi - torr - micron - kPa.

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Air velocity diagrams for vacuum pipe lines.

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Calculate pressure drops in vacuum pipe lines.

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Capacities of vacuum pump exhaust pipes.

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Online calculator, figures and tables giving the boiling temperatures of water in varying vacuum, SI and Imperial units.