Capacitance pressure transducer

In a cell for a capacitance pressure transducer to measure the pressure of a gas having, a cell housing, a tension ring located within the cell housing, a circular diaphragm peripherally connected to the tension ring, and an electrode disk positioned so as to form a plane parallel capacitor plate with the diaphragm;

• the improvement comprising:
• tension ring connection means for connecting the tension ring to the cell housing, the tension ring connection means integrally formed with the tension ring, both the tension ring and the tension ring connection means formed of a metal, the tension ring connection means welded to the housing and having a lower stiffness than the tension ring so that thermal stresses arising from welding and tension ring connection means to the housing and mechanical loadings applied to the cell housing essentially produce deformation in the tension ring connection means rather than the tension ring.

In a cell for a capacitance pressure transducer to measure the pressure of a gas having, a cell housing, a tension ring connected to and located within the cell housing, a circular diaphragm peripherally connected to the tension ring, and an electrode disk located within the tension ring and positioned so as to form a plane parallel capacitor plate with the diaphragm, the improvement comprising:

• an annular support member, at opposite annular ends, connecting the tension ring to the electrode disk, the annular support member having a plurality of fenestrations oriented in an axial direction of said annular support member and dividing the annular support member into a plurality of regions capable of flexing upon differential expansion between the tension ring and the electrode disk.

In a cell of a capacitance pressure transducer for measuring the pressure of a gas having, a cell housing, a plane parallel capacitor plate including a diaphragm, and an inlet tube in communication, at one end, with the interior of the cell housing, the improvement comprising:

• baffle means dividing the cell housing, between the inlet tube and the diaphragm into a diaphragm chamber proximally located with respect to the diaphragm and a baffle chamber located between the diaphragm chamber and the inlet tube and through which the gas flows before reaching the diaphragm chamber for allowing the gas to reach thermal equilibrium with respect to the cell before reaching the diaphragm.

In a capacitance pressure transducer having, an external enclosure and a cell including, a cell housing containing a plane parallel capacitor plate, and an inlet tube connected to the cell housing and extending from the external enclosure, an environmental enclosure located within the external enclosure and enclosing the cell housing with the inlet tube extending therefrom, electrical heating means for heating the environmental enclosure and thereby the cell housing and the plane parallel capacitor plate to a temperature above the surrounding ambient atmosphere, and temperature sensing means connected to the environmental enclosure for generating a signal referable to the temperature of the environmental enclosure and used in controlling the electrical heating means so that the temperature of the environmental enclosure is constant, the improvement comprising:

• electrical conductor means for conducting the signal to a temperature controller;
• the electrical conductor means connected to the environmental enclosure and in good thermal contact therewith to shunt heat from the environmental enclosure to the temperature sensing means and thereby, to prevent the cooling thereof.