In order to indicate or measure pressure, a reference pressure is required. The atmospheric pressure normally serves as the reference pressure. The pressure measuring device indicates how much higher or lower the measured pressure is in comparison to the atmospheric pressure (pressure measuring device for overpressure).
The indication of the pressure is made by a pointer on a dial with a standardised scale range over 270 angular degrees. If the pressure measuring device is, in addition, filled with a liquid, then the measuring instrument is optimally protected by dampening against destruction from high dynamic pressure loads or vibrations.
In the wide WIKA portfolio, you will always find the right instrument for pressure measuring and pressure indication: