Carbon monoxide sensor

[Areeha Durrani]

I am working on a project and i need to know what is the best smart sensor for measuring concentration of Carbon monoxide in ppm?I have to interface it with arduino to check the atmospheric readings.

 

[(*steve*)]

MQ-7

 

[Areeha Durrani]

Will it give the exact readings of ppm?

 

[Areeha Durrani]

Because i have been working on the MQ 9 sensor but the readings obtained have a huge percentage error.
Like in a room,i get ppm values for carbon monoxide of 244 ppm.While it should be <10 ppm

 

[(*steve*)]

MQ9 is also sensitive to other gases like methane

 

[Areeha Durrani]

But will MQ7 give me correct ppm readings?that i cant obtain from MQ 9

 

[(*steve*)]

That's what the datasheet suggests. Have you read it?

 

[Areeha Durrani]

Datasheet of MQ9 says that it accurately reads ppm from 10-1000ppm.But it isnt giving the readings as its graph starts from 130 ppm (log graph)

 

[(*steve*)]

But given the sensitivity of the MQ9 to methane, you need to be sure you haven't eaten beans because your own methane emissions may swamp the CO level.

Are you able to extrapolate the graphs? I thought something I read suggested that the MQ7 has a resistance which varies linearly with concentration (I may be wrong)

 

[Areeha Durrani]

I plotted the readings of Concentration versus Rs/R0 on excel from 130 ppm to 1000 ppm as given in the graph and generated an equation which gives correct result of Rs/R0 corresponding to the concentrations.For e.g; it should give 333.33 approx on 2.5 Rs/R0. But i dont think this much amount of concentration exists in a closed room.
Hence the readings i am getting are correct in terms of the graphical data.But does not match the real values that exist.

 

[(*steve*)]

How can I write this more clearly...

WHAT ABOUT THE OTHER GASSES IT IS SENSITIVE TO?

 

[Areeha Durrani]

okay okay,i just replied to what you had asked bro!

 

[(*steve*)]

Yeah but you ignored the most important part of what I said. And what at I've been saying for most of my posts.