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:
Mar. 05, 1996
Filed:
Sep. 30, 1994
Roberta A Herman, Cranberry Township, PA (US);
Daniel E Bruce, Murrysville, PA (US);
Alan A Schneider, Wexford, PA (US);
Stephen E Long, Murrysville, PA (US);
Mine Safety Appliances Company, Pittsburgh, PA (US);
Abstract
A gas detection device is provided comprising an exterior housing in which an active pelement and a compensating pelement are disposed. The gas detection device further comprises a porous frit seated within a distal end of the exterior housing to separate the active pelement and the compensating pelement from the surrounding environment. The porous frit is adapted to prevent flashback into the surrounding environment while allowing movement of environmental gas through the porous frit to contact the active pelement and the compensating pelement. The gas detection device further comprises a flow guide for directing flow of environmental gas into the gas detection device disposed adjacent the exterior side of the porous frit. The flow guide comprises an inlet port through which a forced flow of environmental gas is pumped to pass through the porous frit and into the exterior housing in a direction generally parallel to the axis of the exterior housing. The flow guide also comprises an outlet port through which gas may exit the exterior housing. A gas detection device is also provided in which the electrical resistance of the compensating pelement is measured to determine concentration of combustible gas at combustible gas concentration levels above a predetermined concentration level set equal to the LEL (Lower Explosive Limit). The gas detection comprises a circuit for reducing current passing through the active pelement when the gas detection device is being used above the predetermined concentration level.