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>Posted on 1 Aug 1996 at 15:29:47 by Marvin Rosen

>How do you calibrate an o2 sensor using a voltmeter? will measuring air
>then 100% o2 are the sensors linier? Any recomendations as to which
>sensor to use and where to get one?


Assuming the measurements are taken at 1 atmosphere
you basically need to correlate a known %O2 with the
voltage output by the sensor in question.

If the sensor output depends solely on %O2 and is
perfectly linear in %O2 you will get a straight line
if the data points are plotted as x-y data on linear
graph paper.

In this case any two data points (not equal) would
suffice to define a line.


But in real life such factors as gas flow rates,
temperatures, storage temperature, temperature compensation,
humidity, hysteresis effects, internal impedance, load
resistance, age, offset voltage, deviation from linearity
etc. etc. will cause a deviation from linearity or systematic
errors between measurements.

There could also be a weak correlation between the output
voltage of the sensor and the partial pressures of the
other gases present in the mixture that's being analyzed
for %O2.


There are many different sensors available.

Which one to get depends on how accurate a measurement
you need along with issues like expected life, initial
cost etc. etc.


Regards,
John

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