Pitfall 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 made use of this functional principle in the center of the 19th century. It is based on an elastic spring, a c-shaped, bent tube having an oval cross-section.
The effect of pressure on a Bourdon tube
When the internal space of the Bourdon tube is pressurised, the cross-section is thus altered towards a circular shape. Audacity that are created in this technique raise the radius of the c-shaped tube. Due to this fact, the end of the tube moves by around two or three millimetres. This deflection is a way of measuring the pressure. It really 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 around 60 bar can be displayed. For higher pressures, helical or spiral-type Bourdon tubes are employed. With respect to the geometry, material and material thickness, pressures around 7,000 bar could be realised. Based on the requirement, the pressure elements are constructed of copper alloys, stainless steels or special materials such as Monel.
Note
More info on Bourdon tube pressure gauges are available on the WIKA website.