Device for measuring pressure levels in fluid media. They may function directly (e.g. vertical column pressure gauge) or indirectly, whereby elastic deflections, for example, are used to record the pressure level.
The pressure gauges used in fluid technology almost always operate indirectly via measuring devices with a spring, whose deflections are relayed to a pointer. In terms of the structure, a distinction is made between tube-type, diaphragm, bourdon tube and corrugated tube pressure gauges (Figure M 1 a and b).
Figure M 1a: Dynamic pressure gauge with tube; the pressure difference between the pressure in the tube in the spring-based measuring device (1) (Bourdon tube) and the atmospheric pressure causes the free end of the tube to undergo proportional linear deflection. It is relayed via the connecting rod (2) to the pointer (3) and displayed on the scale (4).
Figure M 1b): Dynamic pressure gauge with diaphragm; a diaphragm with a concentric corrugated design stretched between two flanges (1) splits the pressure compartment into two pressure chambers. Pressure chamber (2) is connected to the atmospheric pressure. Chamber (3) is subjected to the operating pressure at the measuring point. A pressure difference between (2) and (3) causes the diaphragm to deflect accordingly. This deflection is relayed via the push rod (5) to the pointer and displayed on the scale (4).