Hi

I am looking for any information on how I could calibrate the NH3 and CO sensors?
I have available an already calibrated sensor for NH3 and one for CO.

I would definitely appreciate a response before the weekend ..

Thank you

Hi evival,

to calibrate the sensor properly you should use a gas chamber and measure the output under different concentrations in the range of use. Your calibrated sensor will help you to determine the exact concentration in the chamber if you don't have a way to regulate it.

Regards.

Hi,

thank you for your answer. I didn't mean that, though. My mistake. Did not clarify.

I meant, while doing what you described, I am changing the values of the gain and load resistance, but I am doing this randomly and only based in trial and error

I am looking for info like:

increasing the gain --> increases the sensitivity/ gets saturated with less concentration...
increasing load resistance --> ......

In this way knowing more or less the concentration to be measured we can choose the values for gain and load resistor...

Moreover, I would like to confirm how to get the values out of the graph supplied.
We should get a formula out the logarithmic graph, considering the the line as a straight line?
So having the formula and the Ro (in air measurement) we can have the gases values ?

Dont really know (as a developer) if that is the correct path for getting the gases values.

Thank you

Hi evival,

I understand what you meant now.

To choose the load resistor I'd advice you to calculate the resistor of the sensor under the maximum and minimum of the concentration range where it is going to work and set it in the middle, so you have the widest range possible.

Secondly, the amplification stage has been introduced to improve resolution under very low (or high, depending on how the resistance of the sensor changes) concentration values and working under wide concentration ranges, so you can take a more accurate measurement without changing the working conditions of the sensor. When normally working, I'd advice you to set it at '1' and only change it if you are measuring very low output values.

Hope this helps you, best regards.