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:
Nov. 26, 1996
Filed:
Oct. 11, 1995
Warren S Graber, Inverness, IL (US);
Woodhead Industries, Inc., Buffalo Grove, IL (US);
Abstract
A portable electric lamp suitable for use in hazardous locations includes a fixture which is purged continuously with air during operation. Pressurized air is introduced at an input end of the fixture, through a plenum which establishes a generally laminar flow of air through the fixture during purging. To insure that the fixture is satisfactorily purged before power is applied to the lamps, differential pressure is measured over a precision orifice at the discharge end of the lamp, and total flow is determined. During the start-up cycle, pressure within the fixture must exceed a predetermined minimum threshold; but following start-up, the operating pressure may drop lower than the initial minimum pressure, as long as a positive pressure is maintained within the fixture.