The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 30, 1991
Filed:
Jun. 22, 1989
David B Edwards, Harrow, GB;
Racal Safety Limited, , GB;
Abstract
A powered respirator is provided with a device sensitive to the pressure within the respirator in the region of the user's face and adapted to sound a warning in the event that the sensed pressure goes below a selected threshold value. The device includes a flexible diaphragm exposed on its opposite sides to the sensed and atmospheric pressures respectively, and an infra red emitter and receiver arranged so that the level of energy received by the receiver from the emitter depends upon the flexural position of the diaphragm. In different embodiments the diaphragm may be arranged to reflect the radiation from the emitter onto the receiver or not, or to interrupt a beam of radiation from the emitter to the receiver or not, depending on the pressure differential across it. In either case, when a sufficient energy level is detected at the receiver, indicating a pressure level below the selected threshold, power is switched to a sounder to warn the user of the low pressure condition.