DP flow sensor using optical fibre Bragg grating

Abstract An optical-based differential pressure (DP) flow sensor has been developed for an optically-powered hydraulic valve monitoring and feedback control system. The DP sensor employs two optical fibre single-mode Bragg grating elements, which are mounted on either side of the DP sensing diaphragm. The fluid flow-rate signal is obtained in the form of differential optical wavelength shift, and temperature compensation is provided. The sensor has been tested at fluid flow-rates from 0 to 800 cm 3 /s with temperature varying from 25 to 75°C. The optically-powered hydraulic valve using the DP flow sensor as a monitoring system has been tested with hydraulic oil with a flow-rate up to 6 cm 3 /s at a pressure of 700 kPa.