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Powered respirators

  • US 5,035,239 A
  • Filed: 06/22/1989
  • Issued: 07/30/1991
  • Est. Priority Date: 06/25/1988
  • Status: Expired due to Term
First Claim
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1. A powered respirator incorporating a differential pressure sensor comprising a flexible pressure-responsive member arranged to be exposed on its opposite sides to the pressure within the respirator in the region of a user'"'"'s face and to a references pressure respectively, and adapted to flex in response to change in the differential between said pressures;

  • an emitter and a receiver of selected electromagnetic radiation located side by side and facing towards one side of said pressure-responsive member whereby said member flexes towards or away from the emitter and receiver in dependence upon the pressure differential across it;

    in a first spacing of said member from the emitter and receiver said radiation being transmitted from the emitter to the receiver via the surface of said one side of said member and in a second spacing of said member from the emitter and receiver such transmission of radiation from the emitter to the receiver being prevented;

    said member changing from one of said first or second spacings to the other of said first or second spacings when the pressure in said region falls below a predetermined value in relation to said reference pressure; and

    means connected to said receiver to provide an electrical warning signal in response to the change of said member from said one to said other of its spacings.

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