Bourdon tube pressure gauges are the most frequently 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 center of the 19th century. It really 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. The hoop stresses which are created in this technique increase the radius of the c-shaped tube. Subsequently, the finish of the tube moves by around several 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, 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 higher pressures, helical or spiral-type Bourdon tubes are used. 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 created from copper alloys, stainless steels or special materials such as Monel.
Note
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