Bourdon tube pressure gauges are the most regularly 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 really is predicated on an elastic spring, a c-shaped, bent tube having an oval cross-section.
Achieve 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 increase the radius of the c-shaped tube. Due to this fact, the finish of the tube moves by around two or three millimetres. This deflection is really a way of measuring the pressure. It really is transferred to a movement, which turns the linear deflection 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 used. According to the geometry, material and material thickness, pressures up to 7,000 bar can 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 can be found on the WIKA website.