Combustible gas detection system
AssigneeDelphian Partners
InventorEric S. Micko
Life of this patent
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Abstract
Methods and apparatus for measuring combustible gases in which an active sensor is maintained at controlled, temperature in respect of a reference sensor by means of a bridge-sampling system and a variable duty cycle system responsive to the bridge sampling system adapted to periodically bypass the current from the active sensor in a reference bridge network.
Claims10
In a method for detecting combustible gas comprising the steps of placing active sensor and reference sensor elements of a resistance bridge in contact with a gas sample to be analyzed, and providing an electrical current across the bridge, the improvement comprising the steps of periodically diverting the current from the active sensor in response to a feedback control signal without periodically diverting said current from said reference sensor,
- periodically sampling the balance of the resistance bridge while current is flowing in said active sensor to provide a bridge balance signal
- controlling in response to said bridge balance signal, the average time percentage of current diversion from said active sensor to maintain balance of the resistance bridge, and
- utilizing the average time percentage of current diversion from said active sensor to provide a measure of the concentration of combustible gas at the active sensor.
A combustible gas detection instrument comprising
- a resistance bridge comprising an active combustible gas detection sensor and a reference sensor in one current path thereof,
- means for providing an electrical current through said resistance bridge,
- switch means for periodically shunting all current in said bridge from said active sensor in response to a control signal without shunting current from said reference sensor,
- bridge sampling means for periodically sampling the balance of said resistance bridge when electrical current is being conducted through said active sensor and for providing an output signal representative of bridge imbalance,
- means responsive to said bridge sampling means output signal for generating a variable, periodic control signal for said switch means for maintaining the resistance of said active sensor and the resistance of said reference sensor in fixed relationship by varying the average percentage of time that electrical current is conducted through said active sensor, whereby said periodic control signal provides a measure of the concentration of combustible gas at said active sensor.
Dependencies are inferred from the claim text.