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!!
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