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AssigneeMine Safety Appliances Company
InventorsRoberta A. Herman, Daniel E. Bruce, Alan A. Schneider, Stephen E. Long
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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.
A gas detection device for the detection of combustible gases in a surrounding environment comprising, an exterior housing, an active pelement disposed within the exterior housing and a compensating pelement disposed within the exterior housing, the gas detection device further comprising 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 adapted to prevent flashback into the surrounding environment while allowing entry of environmental gas through the porous frit to contact the active pelement and the compensating pelement, the porous frit having an interior side within the exterior housing and an exterior side outside the exterior housing, the gas detection device further comprising 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 comprising an inlet port through which a forced flow of environmental gas is directed by an external pump to pass through the porous frit and into the exterior housing in a direction generally parallel to the axis of the exterior housing to contact the active pelement and the compensating pelement, the flow guide further comprising an outlet port through which gas may exit the exterior housing.
A gas detection device comprising an active pelement, a compensating pelement and a circuit for measuring the electrical resistance of the compensating pelement, wherein the electrical resistance of the compensating pelement is used to determine concentration of combustible gas at combustible gas concentration levels above a 100% LEL (Lower Explosive Limit).
Dependencies are inferred from the claim text.