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Engineering ToolBox > Vacuum

Vacuum is defined as air pressure below atmospheric pressure

• Vacuum in torr, mm Mercury and psi

The vacuum level is the difference in pressure between the atmospheric pressure and the 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.