Study of a Pressure Transmitter Using an Improved Inductance Bridge Network and Bourdon Tube as Transducer

A Bourdon tube is a mechanical-type pressure sensor. It is generally used in a local pressure indicator and display. Hence, a special technique is needed to transmit to and display the reading of a Bourdon gauge at a remote distance. In this paper, an improved inductance bridge-type technique has been developed to convert the Bourdon tube movement into an electrical current signal which can be transmitted to a remote indicator. A bent ferromagnetic wire attached to the tip of the Bourdon tube acts as a sensing element of pressure. The movement of the wire as a result of pressure variations inside an inductive pickup coil changes the self-inductance of the coil with the changes in pressure. An improved inductance bridge network has been utilized to measure the self-inductance of the coil more accurately when compared with the readings by an LCR meter. It has been observed that the variation of the self-inductance of the pickup coil as well as the variation of the transducer and transmitter outputs with pressure has very good linearity and repeatability. The necessary theoretical equations, along with the experimental results, are reported and compared in this paper.