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Pressure monitoring method and apparatus

  • US 4,393,878 A
  • Filed: 05/11/1981
  • Issued: 07/19/1983
  • Est. Priority Date: 11/28/1980
  • Status: Expired due to Term
First Claim
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1. Pressure monitoring apparatus comprising:

  • (a) a fluid pressure pump supplying gas under pressure;

    (b) a pressure sensor including;

    (1) a cup shaped housing having an open mouth and having an inlet and an outlet formed therein;

    (2) a flexible diaphragm sealed over the open mouth of the housing to define a plenum between the walls of the mouth in the housing and the diaphragm, and wherein the inlet formed in the housing is in communication with the plenum;

    (3) an exhaust tube centrally mounted in the housing within the plenum with an end thereof terminating adjacent the inner side of the diaphragm and connected to be in communication with the outlet from the housing;

    (c) tubing connecting the pump to the inlet in the sensor housing to supply gas under pressure to the inlet and also connecting the outlet in the sensor housing to the pump to form a closed system;

    (d) a flow restriction connected in the tubing between the pump and the inlet to the sensor housing so that the flow to the sensor is substantially uniform; and

    (e) means for measuring pressure connected to measure the pressure in the tubing between the flow restriction and the inlet to the sensor housing, whereby changes in ambient pressure at the pressure sensor will result in movement of the diaphragm to alternately open and close the exhaust tube to automatically maintain the pressure within the plenum approximately equal to the ambient pressure, and whereby the means for measuring pressure in the tubing will measure a pressure which is approximately equal to the pressure within the plenum.

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