Bourdon Tube Pressure Gauge

The Bourdon tube pressure gauge, named after Eugène Bourdon, is a very popular pressure sensor. Basic Bourdon tubes are made from metal alloys such as stainless steel or brass. They consist of a tube of elliptical or oval cross-section, sealed at one end. There are various shapes of Bourdon tube, including helical, spiral, and twisted. A common design is the C-shape, as shown in Figure 18.4. When increased pressure is applied to the open end, it deflects outwards (tries to straighten) in proportion to the pressure inside the tube (the outside of the tube remains at atmospheric pressure). As the pressure is decreased, the tube starts to return to its atmospheric pressure position.

Figure 18.4 (a) Working of Bourdon Tube Pressure Gauge and (b) Bourdon Tube Pressure Gauge

The Bourdon tube pressure gauge, shown here, consists of a Bourdon tube connected to a pointer. The pointer moves over a calibrated scale. When pressure is applied, the movement of the tube is fairly small, so to increase the movement of the pointer it is mechanically amplified. This is usually by a connecting mechanism consisting of a lever, quadrant, and pinion arrangement.