When to discard analyzer O2 sensor?

[Pao]

There are two common failures for O2 sensors. Linear deviation and limiting. For your application limiting is a concern if it reaches the point that it will affect the percentage of O2 content to be analysed. With linear deviation the amount of deviation will affect any O2 percentage being measured. For your application you need to test for both limiting and linear deviation and decide how much deviation is acceptable. My personal comfort level with deviation will depend on the the application (dive profile). Keep in mind that we already allow for a variance of 0.1 on either side of output for measuring inaccuracy, any linear deviation from there will increase the variance. I calculate in mv, when calculating in PO2 there is less accuracy.

This is getting out of hand. These sensors are actually partial pressure and not absolute sensors. Thoughts are now running in my brain of making a self contained unit with a pressure sensor and a data logging module and chucking it in a pressure pot. :-D

 

[tmassey]

This is getting out of hand. These sensors are actually partial pressure and not absolute sensors. Thoughts are now running in my brain of making a self contained unit with a pressure sensor and a data logging module and chucking it in a pressure pot. :-D

You would be far from the first person. Check out this link: http://wrecklessdiver.com/building-50-o2-cell-checker/

 

[Hatul]

One way to tell is first calibrate to air as usual , then compare a reading of a nitrox tank against another tester with a good sensor. If they disagree it's time to change yours out.

 

[Pao]

You would be far from the first person. Check out this link: Building The Under $50 O2 Cell Checker - wrecklessdiver.com

I do have a DIY pressure pot like that one , but my Shearwaters are SA models and do not have the Fischer connectors. I can just chuck in a computer and record the pressure readings manually. But where is the fun in that? I'm planning to add a pressure sensor module and an SD card reader/writer to record pressure and sensor readings simultaneously.