Bourdon tube pressure gauges are the most regularly used mechanical pressure measuring instruments. Their pressure element is frequently referred to as a Bourdon tube: The French engineer Eug�ne Bourdon used this functional principle in the middle of the 19th century. It really is predicated on an elastic spring, a c-shaped, bent tube with 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 finish of the tube moves by around several millimetres. This deflection is a measure of the pressure. It really 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 around 60 bar can be displayed. For higher pressures, helical or spiral-type Bourdon tubes are used. With respect to the geometry, material and material thickness, pressures around 7,000 bar could be realised. Depending on Authoritative , the pressure elements are made of copper alloys, stainless steels or special materials such as Monel.
Note
More info on Bourdon tube pressure gauges can be found on the WIKA website.