High vacuum capacitance manometer having Px side open housing

• US 4,587,851 A
• Filed: 02/26/1985
• Issued: 05/13/1986
• Est. Priority Date: 02/26/1985
• Status: Expired due to Fees

• Current Assignee: Vacuum General, Inc. (Entegris Incorporated)
• Original Assignee: Edward Mortberg
• Inventors: Mortberg, Edward
• Primary Examiner(s): WOODIEL, DONALD
• Application Number:
  US06/705,570
• Time in Patent Office: 441 Days
• Field of Search: 73/718, 73/724, 73/431, 361/283
• US Class Current: 73/724
• CPC Class Codes: G01L 9/0072 using variations in capacitance

Abstract

A sensor unit for a high vacuum manometer includes a tensioned diaphragm fused on one side to a closed evacuated reference chamber and on the other side to a wall ring of substantially the same diameter as the diaphragm. A removable cap member with a gasket seats against the wall so as to define a pressure receiving chamber bordering the diaphragm. With the cap removed, the surfaces of the diaphragm and ring are all accessible for solvent cleaning and visual inspection, so that the sensor may be repeatedly and reliably decontaminated and the diaphragm restored to its initial characteristics. A method of assembly and cleaning are also shown.

Claims

1. A sensor unit for a high vacuum capacitance manometer, of the type having an integral vacuum reference chamber, such unit comprising:

a diaphragm having first and second sides and a periphery;

a reference chamber fused to the diaphragm along its periphery on the first side, and including an electrode and means for securing said electrode in a fixed position with respect to the diaphragm;

a wall ring fused to the diaphragm along its periphery on the second side and extending outwardly therefrom to an outer edge; and

cap means for removably capping the wall at its outer edge so as to provide a closed pressure receiving chamber with the second side of the diaphragm constituting an inner surface thereof, such cap means being non-destructively removable so as to provide, when removed, access to substantially the entire second side of the diaphragm for cleaning and visual inspection thereof.

2. A sensor according to claim 1, wherein the cap means includes pressure actuated vacuum sealing means, for effecting, under the influence of a pressure decrease in the pressure receiving chamber, a vacuum-tight fit of the cap to the wall.

3. A sensor according to claim 2, wherein the wall has a cylindrical inner profile, and the cap includes a cylindrical guide member mating with the inner profile for guiding the cap into position at the outer edge of the wall, and further includes a seal between the cap and the wall, so that drawdown of the pressure in the pressure receiving chamber advances the cylinder within the wall to compress the seal and form said vacuum-tight seal.

4. A sensor according to claim 3 wherein the cylindrical guide member includes an annular groove therein, and wherein the seal is an O-ring located in the groove.

5. A sensor according to claim 1 wherein the diaphragm is a tensioned metal diaphragm and wherein the reference chamber is a vacuum chamber.

6. A sensor according to claim 1, wherein the cap means has inner and outer faces, and further includes conduit means, communicating with the inner face of the cap and extending from the outer face thereof, for conducting the pressure of an outside pressure source to the closed pressure receiving chamber.

7. A sensor according to claim 1, wherein the wall ring comprises an inner wall surface along its outer edge, and wherein the cap means comprises a plug, having an outer surface mating with the inner surface, for removably capping the wall by plugging it.

8. A sensor according to claim 7, wherein the plug includes a recess in its outer surface, and the cap means further includes a gasket located in the recess, so as to provide a vacuum-tight fit of the plug to the wall.