Bourdon tube pressure gauges will be the most frequently 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 based on an elastic spring, a c-shaped, bent tube with an oval cross-section.
The effect 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 technique raise the radius of the c-shaped tube. Consequently, the end of the tube moves by around several millimetres. This deflection is really a measure of the pressure. It 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 Verify , helical or spiral-type Bourdon tubes are employed. With regards to the geometry, material and material thickness, pressures up to 7,000 bar could be realised. Depending on the 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 are available on the WIKA website.