I am having some confusion regarding which datasheet to use for the MQ-137 sensor. I am coming across two versions, which seem to be different. Any advice on which one to use would be appreciated.
MQ137 pdf, MQ137 Description, MQ137 Datasheet, MQ137 view ::: ALLDATASHEET :::
Looks like two different companies make basically the same sensor.
What differences are you concerned about?
Since they are both pretty sketchy, search the web for practical info. The most important things to remember are that these sensors have to be "burned in" for 48 to 72 hours before the readings stabilize, they are uncalibrated, and react to many different compounds.
The code we are writing requires a point from the ammonia line on the graph as well as the slope of the line and the RL value. I'm not sure which datasheet to pull those numbers from. I know they are not precise instruments, but I don't want to be off by a factor of 10.
You cannot. These sensors MUST be calibrated against a known standard.
They are dirt cheap for a reason.
Since ammonia is so extremely dangerous, for reasons of human safety use a commercial, calibrated and certified ammonia sensor instead.
Thanks for the reply. For reasons of cost and project design, a commercial ammonia sensor is not a possibility. I understand that there are obvious limitations of using the MQ sensor, but that is what we have to work with.
What do you think about this code?
RL_VALUE = 5 # define the load resistance on the board, in kilo ohms
RO_CLEAN_AIR_FACTOR = 9.83 # RO_CLEAR_AIR_FACTOR=(Sensor resistance in clean air)/RO, which is derived from the chart in datasheet
Understanding that limitations exist, which datasheet should the numbers come from?
Hello. i'm a newbie, did you get the answer? i need it too for education reasons
The person who started the thread was unwilling to spend the time to calibrate the sensor they had, so the particular values they wanted to use are meaningless. Are you going to calibrate your sensor so you know what values to use?
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