The following is an excerpt from “Chemistry in Britain” April, 1999.


Setting the standard

Among the most vociferous proponents of electrochemical detection technology is George Kerr of Aim Safe-Air Products, a manufacturer of CO detectors based in Austin, Texas, UL.  Kerr points out that even approved optical and MOS-based detectors, which meet the required safety standards, often fail to operate correctly, either giving false alarms or – more seriously – failing to sound the alarm when dangerous concentrations of CO are present.  Kerr’s view is backed up by the Chicago-based Gas Research Institute (GRI), which in 1997 tested 96 CO detectors of different types, and concluded that electrochemical  detection technology gave the best performance.  The GRI’s report expressed concern that the existing North American safety standard (UL 2034, set by Underwriters Laboratories (UL), an independent safety testing and certification organization based in Northbrook, Illinois, US) was not strict enough to ensure acceptable performance of detectors.

Partly due to this concern, the American Gas Association has created the International Approval Services (IAS) 696-98 standard, which is designed to reduce false alarms and false negatives, and to increase reliability, accuracy and repeatability.  So far, says Kerr , the only CO detector to meet the IAS 696-98 standard is that manufactured by his company.  This detector has a patented self-testing mechanism that produces a small burst of hydrogen, by electrolyzing moisture from the air, to test the sensor every 24 hours.  The detector responds to hydrogen in a similar way to CO, so the system actually checks the operation of the sensor, unlike conventional test buttons that only test the alarm circuits.   If the sensor fails to respond to the test, a malfunction alarm is sounded.

However, even these detectors are not the end of the story.  George Kerr told Chemistry in Britain that Aim Safe-Air Products is currently collaborating with a British company, Analox Sensor Technology, to develop new CO sensors based on more advanced technology.


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