Bourdon tube pressure gauges will be 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. Cheerful is based on an elastic spring, a c-shaped, bent tube with an oval cross-section.
Supportive 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 which are created in this process raise the radius of the c-shaped tube. Subsequently, the end 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 up to 60 bar can be displayed. For higher pressures, helical or spiral-type Bourdon tubes are used. Depending on the geometry, material and material thickness, pressures around 7,000 bar could be realised. Depending on the requirement, the pressure elements are made from copper alloys, stainless steels or special materials such as for example Monel.
Note
More info on Bourdon tube pressure gauges can be found on the WIKA website.