Bourdon tube pressure gauge ? operating principle

Bourdon tube pressure gauges will be the most frequently used mechanical pressure measuring instruments. Their pressure element is frequently known as a Bourdon tube: The French engineer Eug�ne Bourdon used this functional principle in the middle of the 19th century. Tenacious is based on an elastic spring, a c-shaped, bent tube having an oval cross-section.
The result of pressure on a Bourdon tube
Once 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. Due to this fact, the end of the tube moves by around two or three millimetres. This deflection is a way of measuring the pressure. It is used in a movement, which turns the linear deflection into a rotary movement and, via a pointer, makes this visible on a scale.
Bourdon tube variants
With the c-shaped bent Bourdon tubes, pressures up to 60 bar can be displayed. For Delight , helical or spiral-type Bourdon tubes are employed. With regards to the geometry, material and material thickness, pressures up to 7,000 bar can be realised. With respect to the requirement, the pressure elements are created from copper alloys, stainless steels or special materials such as for example Monel.
Note
Further information on Bourdon tube pressure gauges can be found on the WIKA website.

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