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  • Author Author: gelmi
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Carbon monoxide sensor jar test

gelmi

As promised I uploaded the video from the tests. Because I do not have a special equipment to test the sensor with the exact ppm value gas concentration, I wondered how to create CO gas in home conditions without risking CO poisoning. I came with this idea. When something organic burns it creates CO2 and H2O (complete combustion), but if there is not enough O2 in the environment (half combustion) the CO instead of CO2 is produced. The simple way to do that is to burn something in a closed jar. That is how my experiment was conducted.


The video shows the Voutput from the EFM32 opamp (non-inverting amplifier configuration), when the sensor is put inside the jar filled with CO. The first time the CO concentration was low because I put the paper towel inside just after it started to burn. The second time the Voutput equals the supply voltage because the CO concentration was above 1700ppm. 1V output is about 500ppm. After the first test when I took the sensor out, one lead disconnects so you can see that voltage goes off the scale, but the second time it is ok. You can see that in high CO concentrations the sensor’s response is very fast - couple of seconds (in datasheet max response is 60 sec. but for lower concentrations). When I opened the jar, the CO was quickly clearing out and the Voutput was dropping soon after. Please, let me know your thoughts about the test in comments.

 


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  • in reply to vsluiter

    Now I do image (source Wikipedia):

    ConcentrationSymptoms35 ppm (0.0035%)Headache and dizziness within six to eight hours of constant exposure100 ppm (0.01%)Slight headache in two to three hours200 ppm (0.02%)Slight headache within two to three hours; loss of judgment400 ppm (0.04%)Frontal headache within one to two hours800 ppm (0.08%)Dizziness, nausea, and convulsions within 45 min; insensible within 2 hours1,600 ppm (0.16%)Headache, tachycardia, dizziness, and nausea within 20 min; death in less than 2 hours3,200 ppm (0.32%)Headache, dizziness and nausea in five to ten minutes. Death within 30 minutes.6,400 ppm (0.64%)Headache and dizziness in one to two minutes. Convulsions, respiratory arrest, and death in less than 20 minutes.12,800 ppm (1.28%)Unconsciousness after 2–3 breaths. Death in less than three minutes.