The physical quantity pressure is the quotient of force and area.
However the pressure in a liquid column can be calculated with the help of the following formula:
Pressure = Density . Gravitational Acceleration . Height
The SI-unit of pressure is the Pascal (Pa). 1 Pa is equivalent to the pressure which applies vertically and evenly the force of 1 N over an area of 1m². Liquid columns or piston gauges are used for the direct realisation of the unit of pressure. Pressure gauges as standard instruments realise the above mentioned equation directly (Pressure = Force/ Area). Pressure acts on the end face of a weight-loaded rotating piston that moves freely in a vertical cylinder. Gases (air or nitrogen) or liquids (oils) are used as working mediums.
At BEV the pressure is realised with pressure balances. Pressure balances can realise pressures within the range of 20 Pa to 400 MPa and can be used to calibrate pressure measuring instruments.