Dual capsule installed pneumatic pressure cell and pressure transmitter

Abstract

Two symmetrically corrugated diaphragms are bonded to form a capsule of special structure and this is used for sensing displacement caused by applied pressure. The displacement is converted into equivalent capacitance by optimally fixed stack of plates and an electrical signal is picked up from it proportional to capacitance. This signal picked up is then calibrated for pressure acting on the capsules. Use of dual capsule structure doubles the capacitance compared to single capsule structure and this increases the sensitivity nearly two folds. Cylindrical plates are used as capacitor plates to concede maximum capacitance from the available space. The construction details of the dual capsule structure, theory and performance analysis are presented. Also presented are the modifications for realizing differential pressure sensor with the dual capsule structure. Furthermore, for increasing the sensitivity to a further extent multiple capsules structure is also presented.