Mesure gas flow from MQ sensors

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.

gas em.JPG

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.

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