Carbon Monoxide Detector

A carbon monoxide detector is a device that senses the presence of carbon monoxide gas in order to warn people before it reaches dangerous levels, a role made necessary because the gas is colorless, tasteless and odorless and so cannot be detected by human senses, earning it the nickname the silent killer. The detector tracks the gas's concentration over time and sounds an alarm on a graduated schedule, for example within about 60 minutes at 70 parts per million, within about 10 minutes at 150 parts per million, and immediately at 500 parts per million or higher, a design meant to avoid false alarms from brief exposure while still giving real warning of genuine danger. Early detectors in use before the 1990s were simple chemical pads that changed color on exposure to the gas, giving only a visual warning with no alarm sound; as carbon monoxide deaths rose through the 1990s, manufacturers added audible alarms, and by the late 1990s Underwriters Laboratories had split the category into CO alarms meeting its UL 2034 standard and passive CO detectors meeting UL 2075.