Carbon Monoxide Appears Before Visible Smoke in a Smouldering Fire
Before a fire produces visible smoke or a flame, heated material pyrolyses and oxidises incompletely, and the clearest gaseous marker of that incomplete combustion is carbon monoxide. An electrochemical carbon monoxide sensor exploits it: gas diffuses through a membrane to a working electrode, is oxidised, and the resulting current is proportional to concentration, giving a linear, part-per-million reading from a device that draws almost no power. That makes carbon monoxide a genuinely earlier fire signature than smoke in smouldering fires, and it is why fire-detection carbon monoxide sensing appears both in multi-criteria alarms and in canopy wildfire nodes. Two cautions come with it. An electrochemical cell has a finite life, typically five to ten years, because its electrolyte is consumed whether or not it ever sees gas, so these devices carry an expiry date rather than a service interval. And a domestic carbon monoxide alarm is set for human toxicity thresholds over hours, not for fire detection in parts per million, so the two applications are not interchangeable. After this Concept you can say when a carbon monoxide channel will beat a smoke channel, and why the sensor has a shelf life.
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Before a fire produces visible smoke or a flame, heated material pyrolyses and oxidises incompletely, and the clearest gaseous marker of that incomplete combustion is carbon monoxide. An electrochemical carbon monoxide sensor exploits it: gas diffuses through a membrane to a working electrode, is oxidised, and the resulting current is proportional to concentration, giving a linear, part-per-million reading from a device that draws almost no power. That makes carbon monoxide a genuinely earlier fire signature than smoke in smouldering fires, and it is why fire-detection carbon monoxide sensing appears both in multi-criteria alarms and in canopy wildfire nodes. Two cautions come with it. An electrochemical cell has a finite life, typically five to ten years, because its electrolyte is consumed whether or not it ever sees gas, so these devices carry an expiry date rather than a service interval. And a domestic carbon monoxide alarm is set for human toxicity thresholds over hours, not for fire detection in parts per million, so the two applications are not interchangeable. After this Concept you can say when a carbon monoxide channel will beat a smoke channel, and why the sensor has a shelf life.
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