Gaseous detection system

DETAILED DESCRIPTION We claim: 1.
A gas detection system for detecting the presence of and determining the level of a preselected gas, the system comprising: (a) sensing means for sensing the preselected gas, said sensing means including isolation means having an input for receiving a mixture of gases at a substantially constant pressure, and an output for providing a sequential flow of substantially segregated gases, such that the preselected gas as contained within said mixture of gases will be provided in substantially isolated form at said output during a preselected window of time following introduction of said mixture of gases to said input; (b) means for providing a signal when said preselected gas is sensed; wherein said sensing means further includes: a first exhaust outlet; a second exhaust outlet; and first valve means operably connected to said isolation means and said first and second exhaust outlets for selectively connecting said output of said isolation means to said first and second exhaust outlets.
2.
The system of claim 1 wherein said sensing means further includes a sensor responsive to preselected gas and which provides an electric signal in response thereto, said sensor being pneumatically connected in series with said second exhaust outlet.
3.
A gas detection system for detecting the presence of and determining the level of a preselected gas, the system comprising: (a) sensing means for sensing the preselected gas, said sensing means including isolation means having an input for receiving a mixture of gases at a substantially constant pressure, and an output for providing a sequential flow of substantially segregated gases, such that the preselected gas as contained within said mixture of gases will be provided in substantially isolated form at said output during a preselected window of time following introduction of said mixture of gases to said input; (b) means for providing a signal when said preselected gas is sensed; wherein said sensing means further includes: a sensor responsive to preselected gas and which provides an electric signal in response thereto; a first pneumatic pathway connected in series with said sensor; a second pneumatic pathway connected in parallel to said first pathway with said sensor; and valve means for controlling said sequential flow of substantially segregated gases from said isolation means with respect to said first and second pneumatic pathways