Posted by David Petersen on 8/28/2019 to Tech Tips
Carbon Monoxide (CO) Detectors and Ultraviolet/Infrared (UV/IR) Detectors do not have the same chance at longevity. The life expectancy of either of these devices is generally 5 - 7 years. In the case of CO Detectors, it could be considerably less if the environment has an elevated but less than the lethal amount of CO at all times, the CO can build up in the sensor and cause an early demise.
SO let's understand the sensing technology of these devices:
CO Detectors have 4 different technologies depending on cost and sensitivity considerations. Opto-Chemical is the cheapest and the least reliable, it is basically a pad with chemicals that change color when exposed to CO. Biomimetic also uses chemicals, however, it works like the hemoglobin and darkens in the presence of CO, It is more reliable than Opto-Chemical and is less prone to false activations. Electromechanical detectors use a "fuel cell" that measures current in the presence of CO, it can actually give a precise reading of the amount of CO present. It is the dominant technology used today. Semiconductor sensors are heated to 752 degrees Fahrenheit. Different gasses affect the resistance of the semiconductor when heated (Oxygen raises resistance while Carbon Lowers it), an integrated circuit measures the resistance and reports if there is CO present. The cost in power consumed does not make this a popular option and it has a lifespan of months...
The Opto-Chemical, Biomimetic and Electromechanical options have lifespans of no more than 7 years under normal conditions (even if it is used in a device with a 10-year battery).
Testing CO Detectors:
The test buttons on the Opto-Chemical and Biomimetic test the functionality of the sensing chambers by making the detector thing it is looking at a dark sensor pad. The Electromechanical's test button only checks the battery life, internal circuitry, and buzzer. It is no way tests the sensor, the only way to test the sensor is to use a Listed Test Gas like the SDI's Solo C6 or Macurco's CME1-FTD.
UV/IR Detector End of Life is directly tied to it's testing:
UV/IR Detectors have a variety of methods that are used to detect the Ultraviolet or Infrared signatures of certain fires, basically they all measure intensity and flicker. Since these sensors are all sealed from the outside environment and are not exposed directly to hazards, they do have a limited lifespan. Things like the degrading of the glass lens, and the aging of the sensors contribute to their demise. Testing these devices and being able to determine when the End of Life is coming takes consistent practice and precise documentation.
Most UV/IR detectors are tested with a Listed device that is capable of initiating a relatively intense burst of the spectrum of light to match the detector like the Talentum model FE-16091. This burst must be set to the proper frequency to match the "flicker" rate of the detector so that the activation of the detector proves that it is functioning. Now comes the tricky part, how do you know if the detector is beginning to die? The answer is simple, it just needs that consistent testing and precise documentation.
The first time you test a particular detector, you need to document the distance the testing unit is from the detector, the tester's settings and the time it took the detector to react. Every time you test that same detector, you must duplicate the distance and settings then record the time. Once you see an appreciable response time lag then you know it is time to consider replacing the device. Like the CO Detectors, this is maybe 5 - 7 years.
As with all Life Safety devices, it is important to test them in the manner and as frequently as the Manufacturer's instructions tell you to.
If you have any questions, please feel free to call us at 800-837-8175 or write to [email protected].
Have a Life Safety Day!!