Sensor test Diverite Liberty, which deviation is acceptable?

[LFMarm]

A middle age cell is linear up to 2 bar. This cell still works fine but you know it will not last very long anymore. So you can make a very good prediction about remaining sensor life. An old cell will be linear up to 1.5 so you know end is near.

• I have had cells not linear beyond 2.2 but still linear in the working range for more than 12 months.
• I don’t consider a cell that is not linear in the range 1.5-2.0 safe for diving.
• If your bar to keep a cell is linear to 3.5, I expect you are turning down quite a few new cells. What is your ratio of new good to keep vs new not good to keep?

 

[Agro]

Of course you have a variation in behaviour. I had a new cell, linear up to 3.5 bar and 1 week later it was death.

I had cells being linear to 3.5 and 3 month later they were linear to 2.0 only, That was a very fast loss of linearity. Some cells grow older faster, some slower.

I never ever had a new cell being not linear to 3.5

The older the cell the more it looses its linearity, that's for sure.

According to divesoft a loss of linearity of 7% is OK, always compared to 1.0 bar pO2

 

[rjack321]

According to divesoft a loss of linearity of 7% is OK, always compared to 1.0 bar pO2

This is ridiculously high for a brand new cell and there is no way a 7% deviation from expected mV at 1.0 is anything close to linear at 3.5

I am now wondering what exactly are you considering linear at 3.5bar?

 

[Agro]

1 bar pO2=50mV
3 bar pO2=150mV in theory
3 bar pO2=140mV in reality
deviation 7%. According to Divesoft this is still OK.

We are not necessarily talking about new cells. New cells often have a lower deviation, even at 3.5 bar.
Older cells come closer and closer to 7%.
Deviation 8% at 3.5 bar, deviation 1% at 2 bar tells us, cell is rather old. You can not confirm this fact by a test up to 1 or 1.5 bar only.