Drift and calibration

[DDKL]

Hi,

I have an OEII and am wondering whether this is normal as I have never experienced this with any other units of the same model.

After equilibrating to ambient temp and then turning on and calibrating to ambient air, the reading will then begin to drift down, reading under 20 within a minute or two - if I then recalibrate to air it will then start to drift down again. When initially turning on, I have seen readings between 19.4 and 21.9.

Calibrating with air and then checking against 100% Oxygen gives a reading in the 95.6 to 96.5 range.

Analyzing the same tank of 32% shows a variance of up to 1% after calibration with ambient air (done some time apart).

Is this normal or within spec? I am only concerned as I have never seen this amount of variation with another unit.

 

[grantctobin]

How old is the cell? How many mV is it reading? How long do you go between uses?

 

[DDKL]

I’m trying to work out how old the cell is at the moment - I can’t find a reference for the manufacture date that matches the data on the sensor.
P/N 9100-9220-9B
SN 110134

I’m looking for my multimeter right now as I just changed the battery and seem to have misplaced it.

 

[Wibble]

How long have you had it?

Oxygen sensor cells are basically batteries and eventually expire. Cells produce electric current in proportion to the amount of oxygen present — the OEii is basically a multimeter.

Does seem like a failing cell.

 

[DDKL]

Sensor was removed from the package 10/21…

 

[grantctobin]

Sensor was removed from the package 10/21…

And manufactured when?

I’d guess bad cell. Unfortunately the rate at which they deteriorate exists on a spectrum. If the cell hadn’t been used in a while, there’s also some chance airing out could help, but less likely with this decade cell manufacturing methods.

 

[DDKL]

I’m waiting on analox for a manufacture date as the serial doesn’t match their old pattern.

 

[Wibble]

Sensor was removed from the package 10/21…

As in a sealed packet for a replacement cell?

Alas cells fail :-(

 

[DDKL]

Yup. I know they fail - I was just hoping that there might be another explanation so I could avoid the replacement cost!

 

[BlueTrin]

You can try to check if it can read both air and a 100% O2 bottle? That will give you an idea on whether your sensor is limited maybe? I never had your issue with my OEII.

You can buy compatible sensors on the Vandagraph website and they’ll be a lot cheaper. I use a Vandagraph sensor on my OEII