Importance

Loading Importance Indicators...

Abstract

The present invention provides a capacitance pressure transducer of increased thermal and mechanical stability and thus performance over prior art designs. A cell formed by a cell housing containing a plane parallel capacitor plate and an inlet tube is connected to an outer protective cover solely by the inlet tube. The cell housing is contained within an air tight environmental enclosure (also supported solely by the inlet tube) of sufficient rigidity as to isolate the cell housing from changes in atmospheric pressure. The plane parallel capacitor plate is formed by a circular diaphragm peripherally connected to the tension ring and an electrode disk located within the tension ring. The capacitor plate is mechanically isolated by a connection between the tension ring and the cell housing that is more flexible than the tension ring itself and a mounting for the electrode disk by which the electrode disk is connected solely to the tension ring by an annular support member holding the electrode disk in a fixed position relative to the diaphragm. Additionally a baffle plate divides the cell housing into baffle and diaphragm chambers to allow the gas to reach thermal equilibrium with the cell before exposure thereof to the diaphragm. Also, the baffle chamber and inlet tube have characteristic dimensions greater than the mean free path of gas molecules at the lowest pressure to be measured to suppress thermal transpiration effects.

Loading the Abstract Image...

First Claim