Bourdon tube pressure gauges are the most regularly 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 predicated on an elastic spring, a c-shaped, bent tube with 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. The hoop stresses which are created in this technique increase the radius of the c-shaped tube. Therefore, เครื่องมือที่ใช้วัดความดัน 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 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 up to 60 bar can be displayed. For higher pressures, helical or spiral-type Bourdon tubes are used. With respect to the geometry, material and material thickness, pressures up to 7,000 bar can be realised. Based on the requirement, the pressure elements are made of copper alloys, stainless steels or special materials such as for example Monel.
Note
Further information on Bourdon tube pressure gauges can be found on the WIKA website.