We use activated charcoal in air filters of the ventilation system to remove pollutant vapours from the exhaust air. Before the filters, the air is heated a bit to avoid condensation of water. Downstream of the filters, we can measure up to 60 ppm carbon monoxide. This can trigger sensitive fire alarms in the ventilation ducts.

What causes this release of carbon monoxide? Is it simply the slow reaction with atmospheric oxygen on the huge surface of the activated charcoal?

Is there any guideline or technical standard to estimate what concentration of carbon monoxide could be considered normal or no longer normal? Apparently, we have to find a better alarm value for the carbon monoxide detectors.

  • $\begingroup$ I'd have thought that activated carbon absorbed CO rather than releasing it. Unless there is something wrong with the setup and filter (like the incoming air is too warm). $\endgroup$ – matt_black Nov 25 '18 at 0:54

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