Calibration question

mortenkjerulff

I am diving a converted Dolphin, and I always remove my cells from the counterlung when calibrating them (ie. place them in a stream of pure oxygen).
I have never been able to calibrate the sensors when installed in the counterlung and doing O2 flushes, because I find it impossible to completely flush the whole loop with oxygen. That is, there is always some diluent present in the scrubber and other places, that dilutes the pure oxygen in the counterlung before i can complete the calibration.

This makes me curious to how f.ex. Inspiration divers can be sure that their sensors are in pure oxygen when calibrating.

Can someone enlighten me on this ?

Kind regards
Morten

PeteS

We are sure the sensors are not in pure O2 when calibrating. When you do a calibration on the Inspiration there is a "fudge factor" that can be put in to allow for this. On my unit I calibrate using pure O2 but inform the controllers that it will only give a reading of 98%.

And then we can allow for air pressure variations with a mb reading. Vision does that on its own.

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Pete S.

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Scuba_Vixen

I dive a converted Dolphin also and have noticed, at least once recently, exactly what you describe.

I calibrated after an O2 flush, and subsequently got 2 very different readings on the PO2 meter and the Explorer after a dil flush to confirm the calibration. I did another O2 flush, and both readings were way high. (like 1.6 or so)
I thought the cells had puked or something. ..... I then pulled them out and seperately calibrated each one with an O2 deco bottle, and air. They both had mis calibrated in the Rebreather, but once calibrated externally, would read air and 100% perfectly repeatedly.

I plan to always just calibrate them externally from now on. That way I'm damn sure.



Darlene

wedivebc

contact Ron at www.tmishop.com he just made a nice portable pressure pot that is really simple to use. He calibrates at 2.0 po2.

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Cheers,

Dave....

Man is the only animal burdened with the knowledge he will eventually die