Design and development of an optical pressure sensing system using bellows as primary sensor

A new optical type pressure sensing system is proposed in this paper. Bellows, an elastic type sensing element is used to indicate the pressure in the form of displacement of bellows element. For automated process industries, the signal is required to be send to a remote location like control room. In order to send the mechanical movement of bellow corresponding to the applied pressure, to a control room the signal is to be converted in the form of electrical, pneumatic or optical signal. For inflammable industries optical signal transmission is preferred. In this work the displacement of bellow element is first converted into an electrical signal using hall probe sensor then it is converted into an optical signal using (MZI) Mach-Zehnder Interferometer. The proposed sensing system is designed and its theory of operation is developed. The experiment was done on the proposed system and the experimental characteristic shows very good linearity with excellent repeatability.