Years ago we began work on a calibration system for residential carbon monoxide monitors. It involved use of an enclosed housing over the detector and introduction of the appropriate gas mixtures, but there was something bothersome about this approach. Soon, copycats began to appear, but we didn’t pursue this further because of a problem with the method that many were ignoring. We kept at this, and are currently working on this issue because we firmly believe that home carbon monoxide monitors do need to be calibrated. We’ll keep you updated with the results.
What disturbed us at the time was that one of our researchers found that a fixed enclosure around the sensor, was actually counterproductive for calibration as the sensor diminished the concentration in the overall unit by consuming it during the gas detection process (electrochemical cell). The manufacturers of the various gas detectors we used for this testing told us that there was no way this could happen, but every test we executed confirmed this.
What we found was that for a small housing, the concentration of 400 ppm CO/ balance air dropped in 40 minutes to 220 ppm CO/ balance air. Needless to see this was a substantial reduction. We won’t publish the results in their entirety here, since this project is still on going for determining the best way to calibration residential CO detectors, but they confirmed the issue of CO diminishment over and again.