Combustible gas sensor

DETAILED DESCRIPTION Accordingly, it is an object of the present invention to provide a combustible gas sensor by making more uniform the thermal and compositional environment surrounding the reference bead and the measurement bead.
Another object of the invention is to provide a combustible gas sensor having a broad response over a wide temperature range.
Still another object of the present invention is to provide a combustible gas sensor in which the reference bead and the measurement bead are fully exposed for substantial improvement of fluid communication between the beads.
In accordance with the invention the improved combustible gas sensor includes a housing defining an interior containing a reference bead and a measurement bead which are fully exposed by the removal of the shroud or can therefrom.
The beads are electrically connected in series and the reference bead is connected in parallel with a resister to define one side of a Wheatstone bridge.
A liner consisting of a disk defining an inner face and an outer face overlies the reference and measurement beads.
The inner face of the disk is provided with a slot opening at the inner face which is dimensioned to receive the reference and measurement beads therein.
The slot provides a confined space for fluid communication between the fully exposed beads.
A through running opening is disposed in the disk on each side of the slot adjacent the end of the slot in which the reference bead is disposed.
A channel extends from each of the openings and communicates with the slot.
The upper face of the disk is recessed and in combination with a porous closure defines a plenum in which the sample gas is first received prior to entering the through-running openings in the disk.
The sample gas enters the sensors through the porous closure and first contacts the reference bead through the through-running openings and the channels communicating with the slot.
After contact with the reference bead the gas passes through the slot to the measurement bead where combustion of the sought for sample occurs