Units for Vacuum Pressure Measurement

According to SI (short for Le Système International d'Unités), the official unit for measuring vacuum gas pressure is the pascal (symbol: Pa). However, other commonly used pressure units include torr, micron, and mbar.

The choice of vacuum pressure units often depends on regional, application, or industry preferences. In the United States, torr is widely used, whereas mbar is the preferred unit in Europe. Pascal is the standard in many Asian countries.

Torr Vacuum Pressure Unit

One torr (symbol: Torr) is approximately equivalent to one millimeter of mercury in a manometer at 0 °C. In the vacuum industry, the term "micron" is also used; it is derived from the unit torr, where one milliTorr equals one micron.

The unit torr is named after the Italian physicist Evangelista Torricelli, but it is not an SI unit.

mbar Vacuum Pressure Unit

The European vacuum industry commonly uses the metric millibar (symbol: mbar) as a unit for vacuum pressure. The millibar is derived from the bar unit, both of which were originally introduced by Norwegian meteorologist Vilhelm Bjerknes. One mbar is equal to 100 Pa or one hectopascal (hPa).

Previously, the millibar was the standard unit for atmospheric pressure in meteorology. However, today the SI unit hectopascal has replaced it as the official unit for meteorological science and weather forecasts.

Pascal Vacuum Pressure Unit

Pascal (symbol: Pa) is the official SI unit for vacuum pressure and is widely used in physical sciences. One pascal represents the force of one newton per square meter acting perpendicularly on a surface.

This unit is named after Blaise Pascal, a French mathematician, physicist, and inventor who made significant contributions to the understanding of pressure and fluid mechanics.