What is Bourdon Tube

The Bourdon tube uses the bending change or torsional deformation of the tube to measure the pressure of the elastic sensitive element, also known as the spring tube. One end of the Bourdon tube is fixed and one end is movable. Its cross-sectional shape is elliptical or flat. The tube with non-circular cross-section gradually expands into a circle under the action of the internal pressure, and at this time the movable end generates a displacement that has a certain relationship with the pressure. Move the pointer at the movable end to indicate the pressure. The most commonly used Bourdon tube is C type, in addition to spiral type, C type combination, twist type and other types (see figure). The material of Bourdon tube is copper-based or iron-based alloy. Compared with other pressure-sensitive components, it is less sensitive and is often used to measure larger pressures. It is often used in combination with other elastic components.

Use of Bourdon tube 

The Bourdon tube is the measuring element of the pressure gauge, which can be installed on the tee, but there is also a shut-off valve between the impulse pipe and the pressure gauge.

The function of the globe valve is to facilitate maintenance. 

The pressure display controller should be transmitted, and the pressure signal will be transmitted as an electrical signal, which can display the magnitude of the pressure in digital form. As for the word “control”, I have never heard of it, and the general control requires an actuator. The pressure gauge with electric contact is to set a contact on a certain value of the pressure gauge. When the pressure reaches the set value, the electrical contact is turned on. There is a digital output, which can control a certain device, such as a switch and an alarm.

working principle The elastic deformation of the Bourdon tube converts the elastic deformation of the Bourdon tube into a rotary motion through the conversion mechanism of the movement in the watch, causing the pointer to deflect to display the pressure.

The displacement of the end of the Bourdon tube can be directly displayed by the displacement measuring device, for example, the indicator with the potentiometer at the end and the movable iron core of the differential transformer can directly display the displacement. People can improve the performance of Bourdon tube sensors and regulators by choosing materials, but the size design of Bourdon tube can only be approximated by experience in the past. A Bourdon tube with an elliptical cross-section or a flat round cross-section deforms when subjected to pressure p, which reduces the ratio of the length to the radius of the cross-section of the tube a/b, the radius of curvature of the Bourdon tube increases, and the free end of the tube is displaced.

Bourdon tubes are still widely used in many instruments to date, especially for pressure and force measurement.

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