Development of Strain Gauge Pressure Transducer up to 2000 bar

Abstract

A number of pressure transducers, based on strain gauge, capacitance / inductance type, frequency resonators, are commercially available and are being used for sensing and producing an electrical output proportional to applied pressure. These sensors have their own advantages and limitations due to operational ease, linearity, hysteresis error, measurement uncertainty and the costs. Strain gauge type transducers are now well established devices for accurate and precise measurement of pressure within measurement uncertainty up to 0.1 % of full scale. In the present thesis work, an indigenous strain gauge pressure transducer has been designed, developed, tested and calibrated for pressure measurement up to 200 MPa or 2000 bar. The measurement uncertainty estimated using the pressure transducer is found better than 0.1 % of full scale. This transducer is developed using four foil type strain gages, bonded two in axial direction while other two in radial direction, to the controlled stress zones of a tubular maraging steel active cylinder working also as diaphragm. The strain gages are then connected to a Wheatstone bridge arrangement to measure stress generated strains. The pressure is applied through matching connector designed in the same tubular transducer active element. The treaded unique design in a single piece through collar, ferule and tubing arrangement provides leak proof pressure connections with external devices without using additional seals. The calibration and performance checking of the pressure transducer is carried out using dead weight type national pressure standard using the internationally accepted calibration procedure.