Question How to check an analyser O2 cell?

[rjack321]

Where do you look for those specs? My Palm O2 sensor is getting old, but it is still reporting what I expect. But it would be nice to test it.

If it reads 100% then its fine. Once you can't calibrate it to 100% anymore its failed.

You'd have to ask AI, they don't publish specs for that cell on their website.

 

[Manatee Diver]

If it reads 100% then its fine. Once you can't calibrate it to 100% anymore its failed.

You'd have to ask AI, they don't publish specs for that cell on their website.

I am getting 96-98% for oxygen when calibrated on scuba air.

 

[Agro]

I am getting 96-98% for oxygen when calibrated on scuba air.

So sensor seems to be faulty, you must get 100%.

 

[rjack321]

I am getting 96-98% for oxygen when calibrated on scuba air.

This is fairly normal... you are 5x 21% way up there and tiny mV changes at 21% create much larger swings 79% higher.

Is there a 100% calibration point?

 

[Manatee Diver]

Is there a 100% calibration point?

It supports it, but I would be calibrating and testing it with the same tank of gas, which doesn't make sense to me.

 

[rjack321]

So sensor seems to be faulty, you must get 100%.

Not really a big deal if you only want to analyze 32%

 

[rjack321]

It supports it, but I would be calibrating and testing it with the same tank of gas, which doesn't make sense to me.

Basically when you can't turn up the calibration to meet 100% (as a known gas) the cell is past its useful life for tech diving. It may have a little life left as a recreational 32% cell analyzer but that's when you replace the cell

 

[Manatee Diver]

Basically when you can't turn up the calibration to meet 100% (as a known gas) the cell is past its useful life for tech diving. It may have a little life left as a recreational 32% cell analyzer but that's when you replace the cell

I'll give it a try and see if it errors out. I have a spare cell that I bought last year.

 

[Agro]

Not really a big deal if you only want to analyze 32%

That's wrong. An new cell is linear from zero to 3.5 bar, an old cell looses linearity. First between 3.0 and 3.5, then between 2 and 3.5 bar and so on. Here we have a cell which is not linear anymore at 1.0 bar and we do not know where the problem startes. Perhaps at 0.95 bar, perhaps at 0.8 bar. Until now no problem with analysing EAN32. But the point of non-linearity will drop down and we do not know when but it will be soon.

In a Liberty you can measure up to 3.5 bar pO2, that's how you test cells. Great feature. If one cell is not linear anymore at 3.0-3.5 bar I kick it out even if it MIGHT still work from zero to 1.6 bar for a moment. But how long is this moment? We know cell is coming to the end of it's life so why should we wait?

The same we have here, not linear anymore at 1.0 bar. Throw it away.

 

[rjack321]

That's wrong. An new cell is linear from zero to 3.5 bar, an old cell looses linearity. First between 3.0 and 3.5, then between 2 and 3.5 bar and so on. Here we have a cell which is not linear anymore at 1.0 bar and we do not know where the problem startes. Perhaps at 0.95 bar, perhaps at 0.8 bar. Until now no problem with analysing EAN32. But the point of non-linearity will drop down and we do not know when but it will be soon.

In a Liberty you can measure up to 3.5 bar pO2, that's how you test cells. Great feature. If one cell is not linear anymore at 3.0-3.5 bar I kick it out even if it MIGHT still work from zero to 1.6 bar for a moment. But how long is this moment? We know cell is coming to the end of it's life so why should we wait?

The same we have here, not linear anymore at 1.0 bar. Throw it away.

You pointed this out yourself... The functional linearity is lost from the top of the curve. So in an analyzer when you're only reaching 98% instead of 100% what does that mean for your accuracy at 32%? Nothing, that is less than 0.5% deviation. You get more variability from barometer pressure changes than this.

Yes order a new cell, but while you wait for it to arrive you can continue to use that analyzer