Bourdon tube pressure gauge ? operating principle

Bourdon tube pressure gauges are the most regularly used mechanical pressure measuring instruments. Their pressure element is often known as a Bourdon tube: The French engineer Eug�ne Bourdon made use of this functional principle in the center of the 19th century. It really is predicated on an elastic spring, a c-shaped, bent tube having an oval cross-section.
The effect 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 process raise the radius of the c-shaped tube. Because of this, the finish of the tube moves by around two or three millimetres. This deflection is really a measure of the pressure. It is transferred to a movement, which turns the linear deflection 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 can be displayed. For higher pressures, helical or spiral-type Bourdon tubes are used. With regards to the geometry, material and material thickness, pressures around 7,000 bar could be realised. With respect to the requirement, the pressure elements are made of copper alloys, stainless steels or special materials such as Monel.
Note
Happy on Bourdon tube pressure gauges are available on the WIKA website.

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