Pressure p (mbar)
of fluids (gases and liquids). (Quantity: pressure; symbol: p; unit of measure:
millibar; abbreviation: mbar.) Pressure is defined in DIN Standard
1314 as the quotient of standardized force applied to a surface and the
extent of this surface (force referenced to the surface area). Even though
the Torr is no longer used as a unit for measuring pressure (see Section
10), it is nonetheless useful in the interest of “transparency” to mention this
pressure unit: 1 Torr is that gas pressure which is able to raise a column of
mercury by 1 mm at 0 °C. (Standard atmospheric pressure is 760 Torr or
760 mm Hg.) Pressure p can be more closely defined by way of subscripts: