Bourdon tube pressure gauges are the most frequently 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 is predicated 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 which are created in this technique raise the radius of the c-shaped tube. Consequently, the end of the tube moves by around two or three millimetres. Absolutely is really a measure of the pressure. It really 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 up to 60 bar can be displayed. For higher pressures, helical or spiral-type Bourdon tubes are employed. Based on the geometry, material and material thickness, pressures up to 7,000 bar can be realised. According to 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.