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 used this functional principle in the middle of the 19th century. It really is predicated on an elastic spring, a c-shaped, bent tube having 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 which are created in this process increase the radius of the c-shaped tube. As a result, the end of the tube moves by around two or three millimetres. This deflection is a way of measuring the pressure. It is transferred to 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 Bloodcurdling , helical or spiral-type Bourdon tubes are employed. According to the geometry, material and material thickness, pressures up to 7,000 bar could be realised. Based on Hazardous , the pressure elements are constructed with 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.