Arduino gas sensor questions

You know the kit of sensors you can get cheap for the arduino? the gas ones with several gases they can detect? does anyone know if they are actually based around the same sensor?

I dont have a link at the moment as mandline my file system for papers and data sheets is updating and has me locked out . I dont own any of the sensors, so if anyone does i wouldnt mind some feed back on them. I am looking for a cheapo solution for Hydrogen,Methane and CO2 levels, i note the kit come with Carbon monoxide as well which might be handy, i dont expect great accuracy but i dont need that.

I am after some rough measurements in a closed system that is likely to ruin them anyway. This is part of the reactor controller project, I got hold of another reactor by pure luck, so i am back on the trail of building a control system for it.

Hi LG,
have you seen this page on Arduino Playground?
https://playground.arduino.cc/Main/MQGasSensors
Down the bottom, there is a list of a load of different sensors, with gas type for each and links to datasheets, plus examples for some of those in the list.

Regards.

Mickster said:

Hi LG,
have you seen this page on Arduino Playground?
https://playground.arduino.cc/Main/MQGasSensors
Down the bottom, there is a list of a load of different sensors, with gas type for each and links to datasheets, plus examples for some of those in the list.

Regards.

Click to expand...

Thx those are the sensors! They do them in a cheap set, I have the data sheets but mendeley is software i use to keep track of papers etc, when it backs up the database it locks you out!! I couldnt open the drive the sheets were on . What i noticed with the sensors was the readings in the datasheet.

I havnt looked again yet, but just a pluck from the air example, lets say CO2 at x ppm gives you y mV. The problem i saw was lets say the methane sensor also gives you a x reading at y mV at a certain level, so how are you going to know if the gas is Yppm CO2 or Y ppm Methane if both sensors read the correct value for each?

Might just be a datasheet thing, if what i am testing works then we would use ion selective sensors, but not for tests they cost too much. But for now a rough and ready guide is all i am after.