Diaphragm type differential pressure gauge with overpressure relief

Abstract

A sealed differential pressure gauge of the general type shown in Phillips and Zoludow U.S. Pat. No. 3,645,140 in which a sealed housing is provided that includes a flexible diaphragm that is to be exposed to differential pressures to operate a sensitive and accurate motion transmitting indicator device that is in the form of a pivotally mounted helix cooperating with a range spring mounted magnet, with the range spring being linked to the diaphragm so that the movement of the diaphragm, indicates differential pressures and changes thereof, operates the indicator device for reading of the gauge. The housing comprises a housing member and back plate therefor that, together with the rim portion of the diaphragm, are shaped to provide for blowout capability of the gauge that is rearwardly directed out of the back of the gauge should overpressures be experienced when the gauge is in operation. The housing at its front end includes a transparent cover through which the gauge dial is viewed that is threadedly connected to the housing member to provide increasing resistance to blowout through the face of the dial as pressures internally of the gauge are increased. The relationship of the helix, the wishbone mounting arrangement of the helix, the range spring mounted magnet, and the zero set mechanisms are revised to improve sensitivity, provide for ready recalibration and zero setting of the gauge, and increase the gauge operating range.