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Topic: Mesure gas flow from MQ sensors (Read 272 times) previous topic - next topic


Jul 21, 2018, 10:54 pm Last Edit: Jul 21, 2018, 10:55 pm by Vu1000
Hi guys,

I'm working on a project and I'm using a MQ7 CO gas sensor to mesure car CO gas emission, the output of this sensor is in PPM, I'm updating the measure of the car emission every 4 to 6 seconds, and I'm getting a chart like this (see the chart attach), ok now I want to get from this chart the rate flow (every second) and the whole quantity of emission, I want to get it as precis as possible.

To get the flow, there're two ideas in my mind and they both gives me a diffrent results, either I do the output of the sensor (Y(i)) divided by the time between this value (d(i))and the previous value (d(i-1)) or should I do the value of the output minus the previous value of the output divided by the time between the two value.

so in nutshell :

either I do this : Y(i)/[(d(i)-d(i-1))]

or : [Y(i)-Y(i-1)]/[(d(i)-d(i-1))]

if there're any other physical equation or way to get this I will be very happy to learn!

Thank you so much for your time & sorry for my English.


You need a flowmeter. Preferably calibrated in kg/sec but if you also measure temperature and pressure then m3/sec will let you calculate kg/sec. The CO sensor cannot do this on its own.
"The problem is in the code you didn't post."


Hi there thanks for your reply, do you have in mind in refrences of sensor that can help me?

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