Bourdon tube pressure gauge consists of bourdon tube bent into an arc of circle. Cross-section of the tube is elliptical. One end of tube is connected to the point, whose pressure is to be measured. Other end is connected to the rack and pinion through mechanical linkage. The pointer is pivoted on the pinion (Fig. 1).
(a) Schematic view of Bourdon Tube Pressure Gauge.
(b) X-X Section
Fig. 1: Bourdon Tube Pressure Gauge
Working of Bourdon Tube Pressure Gauge
When the fluid (either liquid or air or gas), whose pressure is to be measured, is made to flow through bourdon tube, its original elliptical cross-section tends to become circular. This makes the tube straighten itself out with an increase in radius of curvature. This causes the free end of the tube to move/displace. This displacement of free end of tube creates angular movement in rack and pinion through mechanical linkage. The pointer, which is pivoted on the pinion, moves over a calibrated scale, which directly indicates pressure in terms of N/rn2 or ‘m’ head of mercury.
Advantages of Bourdon Tube Pressure Gauge
- Low cost.
- Simple construction.
- Available in wide variety of range.
- High accuracy as compared with cost.
Disadvantages of Bourdon Tube Pressure Gauge
- Low spring gradient.
- Highly sensitive to shock, vibration and Hysteresis.
Factors to be Considered, While selecting Material for Bourdon Tube Pressure Gauge
- Elastic characteristics suitable for pressure measurement.
- Range of measurement.
- Pressure of medium.
- Temperature of medium.
- Corrosive resistance of medium