Is this how o2 sensors die?

[ScubaBunga]

I have a DIY O2 analyzer with an SS-11a sensor. These normally produce something like 13-16mv. It’s worked great for a few years now and I figured I’d need a new sensor soon. Today I turned it on as I need to test a tank and it reads 0.50mv constant! I assumed as it went bad with age it would start to creep or give inconsistent results, not just flatline at some higher value. Is this normal? I ordered a new sensor but am wondering if I need to dig into the chips/wiring. It was all in a sealed case so nothing should have been jarred loose. Thoughts?

 

[sprockjohnson]

Have you changed the battery on the analyzer? I too have a DIY analyzer using a digital panel meter (OxyHacker design) and have found that it has given me inaccurate readings on at least one occasion when the 9v battery was at the end of its useful life.

 

[ScubaBunga]

Have you changed the battery on the analyzer? I too have a DIY analyzer using a digital panel meter (OxyHacker design) and have found that it has given me inaccurate readings on at least one occasion when the 9v battery was at the end of its useful life.

Yeah it uses a 18650 which powers the arduino. Battery will last for years but yep I tried a fully charged one. Original one was still almost full charge too.

 

[sprockjohnson]

Corroded connection between the o2 cell and the voltage amplifier or arduino board? Just thinking of all the basic troubleshooting items I would check first. I had an old cell that was a few years old that could still be calibrated in air, although it was outside the 9-13mv range of the sensors I typically use, but even so it had far more mv's than 0.50mv.

 

[broncobowsher]

Maybe a failure of the internal circuit in the cell. I had one once that would swing depending on the pressure and direction on the connector. I know there can be issues with the internal board.

 

[Johnoly]

I have a DIY O2 analyzer with an SS-11a sensor.

This is an O2 sensor, but I don't think it's an SS-11a. But I've had repeatable results like you see in this video and the sensors are only 2-3 months old. It may or may not apply to your question.

 

[ScubaBunga]

I have a DIY O2 analyzer with an SS-11a sensor. These normally produce something like 13-16mv. It’s worked great for a few years now and I figured I’d need a new sensor soon. Today I turned it on as I need to test a tank and it reads 0.50mv constant! I assumed as it went bad with age it would start to creep or give inconsistent results, not just flatline at some higher value. Is this normal? I ordered a new sensor but am wondering if I need to dig into the chips/wiring. It was all in a sealed case so nothing should have been jarred loose. Thoughts?

I got my answer yesterday. New sensor arrived and all works as designed again. So I guess at least sometimes O2 sensors just go from working to dead in a few weeks between uses.

 

[michael-fisch]

A dropped O2 sensor that hits the floor will usually instantly stop working. Be carefull when you are fumbling with sensors in bad light, it could really mess up your rebreather diving unless you carry a working spare sensor.

Michael

 

[MikeHoncho]

O2 sensors should be seen as consumable. Takes a while but they will all reach their end of life and fail. O2 sensors specifically age no matter if the meter is on or not and are very susceptible to sensor poisoning from silicone and ethanol vapors. Keep them in a zip lock bag.