Importance

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Abstract

A pressure sensing transmitter is provided that has high overpressure protection. The transmitter includes an housing having a first cell, a second cell, a sensing chamber, first and second pressure signal receiving means, and a differential sensor chip for measuring the pressure differential between the first and second pressure signal receiving means. Each cell further includes a cylinder with a clearance of an overpressure diaphragm mounted on the housing, an isolation diaphragm mounted on the other face, and a channel coupling the overpressure and isolation diaphragm and further coupling one cell to the first pressure signal receiving means and the other cell to the second pressure signal receiving means. Each overpressure diaphragm is positioned such that an overpressure protection cavity is formed between it and the housing. The first cell cavity is further coupled to the second pressure signal receiving means and the second cell cavity is further coupled to the first pressure signal receiving means. This arrangement allows a predetermined absolute pressure applied against one of the isolation diaphragms, subsequently transmitted to the sensing chamber via one of the pressure signal receiving means, to collapse an appropriate overpressure diaphragm to relieve one of the pressure signal receiving means of the excess pressure.

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First Claim