The pressure p is the quotient of the normal force F that acts on a surface, and the area of this surface A (DIN 24 312):
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The derived unit for pressure in the SI system is the pascal: 1 Pa = 1 N/m2. In fluid technology p is mostly stated in bar (1 bar = 105 N/m2). However, MPa (106 N/m2) is also used.
Pressure figures, if not otherwise stated, in fluid technology are to be understood as overpressure, i.e. with atmospheric pressure as the reference variable.
The pressure of a medium is one of the most important parameters in fluid technology. It occurs, as shown, in numerous variants that each have a specific significance for the system.
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Possible forms of pressure in a hydraulic system