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 used this functional principle in the center of the 19th century. It is predicated on an elastic spring, a c-shaped, bent tube with an oval cross-section.
The result 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 raise the radius of the c-shaped tube. Because of this, the finish of the tube moves by around several millimetres. This deflection is really a measure of the pressure. Corpse 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 could be displayed. For higher pressures, helical or spiral-type Bourdon tubes are employed. With respect to the geometry, material and material thickness, pressures up to 7,000 bar can be realised. Depending on requirement, the pressure elements are constructed of copper alloys, stainless steels or special materials such as Monel.
Note
Further information on Bourdon tube pressure gauges can be found on the WIKA website.