Bourdon tube pressure gauge ? operating principle

Bourdon tube pressure gauges will be the most regularly used mechanical pressure measuring instruments. Their pressure element is often referred to as a Bourdon tube: The French engineer Eug�ne Bourdon used this functional principle in the center of the 19th century. It really is based on an elastic spring, a c-shaped, bent tube with an oval cross-section.
Fool of pressure on a Bourdon tube
When the internal space of the Bourdon tube is pressurised, the cross-section is thus altered towards a circular shape. The hoop stresses that are created in this technique increase the radius of the c-shaped tube. Due to this fact, the finish of the tube moves by around two or three millimetres. This deflection is really a measure of the pressure. It really is used in a movement, which turns the linear deflection right into a rotary movement and, with a pointer, makes this visible on a scale.
Bourdon tube variants
With the c-shaped bent Bourdon tubes, pressures around 60 bar could be displayed. For higher pressures, helical or spiral-type Bourdon tubes are used. Based on the geometry, material and material thickness, pressures around 7,000 bar could be realised. With respect to the requirement, the pressure elements are constructed with copper alloys, stainless steels or special materials such as for example Monel.
Note
More info on Bourdon tube pressure gauges are available on the WIKA website.

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