[SOLVED] Output from mq-2 gas sensor and how to read concentration from mq-2 sensor

[alphonsjp]

Hi all..
I'm new to this group. As part of my project, I would like to know whether MQ-2 sensor can give mV output for lpg?
And I would also like to know how to read the ppm directly from sensor. I mean whether it is having any linear relationship between sensor output and concentration level.
Please help me.. Its really urgent..

 

[FvM]

The datasheet shows a sensor resistance versus concentration curve. This is relative resistance, the referred Rs can vary by a factor of 10 between sensor exemplars, and the relation is nonlinear, but following a Y = X^c characteristic, the points are on a straight line in log-log scale.

You can calculate output voltage versus concentration from this curve and check, if you need linearization for your application. In any case, a calibration óf individual sensors is required.

 

[alphonsjp]

The datasheet shows a sensor resistance versus concentration curve. This is relative resistance, the referred Rs can vary by a factor of 10 between sensor exemplars, and the relation is nonlinear, but following a Y = X^c characteristic, the points are on a straight line in log-log scale.

You can calculate output voltage versus concentration from this curve and check, if you need linearization for your application. In any case, a calibration óf individual sensors is required.

Thank you so much sir. This is really helpful for me..

 

[alphonsjp]

Dear Sir
Could you please explain why we need calibration of individual sensors? And I read in one of the papers like if a sensor is calibrated for 100% LEL of methane, then we need to calibrate sensor before it is used for lpg gas detection? I'm not getting the real meaning of this calibration.

 

[FvM]

Did you read the MQ-2 datsheet, particularly the Rs range specification?

Personally, I won't account MQ-2 or a similar SnO2 sensor as reliable LEL detector. Maybe a catalytic sensor (pellistor).

But any sensor needs invidual calibration and periodical recalibration for reliable operation.