Bourdon tube pressure gauges are the most regularly used mechanical pressure measuring instruments. Their pressure element is frequently known 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.
Largest 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 increase 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 way of measuring the pressure. It really is used in a movement, which turns the linear deflection right 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 employed. Depending on the geometry, material and material thickness, pressures up to 7,000 bar could be realised. Depending on requirement, the pressure elements are constructed with copper alloys, stainless steels or special materials such as Monel.
Note
Further information on Bourdon tube pressure gauges are available on the WIKA website.g