VR3 O2 cell calibration

mortenkjerulff

I use a VR3 as primary ppO2 monitor and a Monroe display as secondary.

When I calibrate the Monroe display in air and then measure 100% oxygen it is spot on and vice versa.

When I calibrate the VR3 in air and then measure 100% oxygen it shows ~1.15. When I calibrate in 100% oxygen and measure air it shows ~0.19.

Has any of you experience this on a VR3 with O2 cell connected?

Morten

Nick uk.

When measuring O2 set 98%
When measuring air set 20.8%

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divechief2000@hotmail.com

onetime

I'm not familiar with a Monroe display. Sounds like the VR3 is connected to a bad cell.

Are you using the same sensor for both calibrations or are they separate? If they're separate, try swapping them. If the VR3 now calibrates and the other doesn't then you've got a bad sensor. Replace it.

SteveL

Hello,
Sensor could be the problem but can I ask a dumb question and I dont mean to be rude - but it desnt sound like you are actually calibrating at all.

Sounds like your VR3 is using the cal data from a different cell and hasnt updated with the new output levels for whatever cell you are using. Remember you cant calibrate the VR3 on one cell then swap cells. If you are getting such high readings then a correspondingly lowreading it seems odd that the cell is faulty.

Regards,

Steve

mortenkjerulff

A Monroe display is just ppO2 display made by a guy with that family name :-)

I have tried swapping the cells, with the same results.

Actually, the reason that I write just now is that I have 2 brand new cells. I also thought it was a cell problem before.

Morten

mortenkjerulff

Hi Steve.

All suggestions are welcome, of course.

But I am calibrating with the same cell, and as I wrote in an other answer I am quite sure the cell is not faulty either.

It looks like it is a VR3 problem

Anyway, I calibrate on 100% and dive with a setpoint of 1.00 and it works fine. It still annoys me though...

Morten

onetime

Well, it's not too uncommon for "new" cells to be bad right out of the box. A bit more doubtful but still possible that you'd get two bad "new" cells unless the seller was holding onto them for a long time or they were from the same bad batch from the manufacturer.

I'm not too familiar with the VR3 so I'd be double checking the procedure and set up of it with the manual. Then I'd call the manufacturer and get some help.

Mdemon

Are you calibrating the VR£ in the rebreather? If so, the procedure for the flush needs to be a bit more than the Inspo calibration because of the cell position. Not wishing to teach you to suck eggs, and I suspect you are calibrating outside the loop, but just in case...

Calibrate Inspo. Empty lungs through nose (turn off ADV!). Flush with O2 - I let the lungs fill up. Repeat three times. The hope is that any nitrogen in the loop will be flushed out and any that remains will be as inisgnificant as possible. Make sure the loop is at ambient pressure (otherwise you'll get a duff reading) and calibrate.

(That said, my VR£ always reads 0.1 lower than the Inspo, despite the linearity check being fine. OK, that would be useful if the handsets failed, but I don't use it for deco plumbed in. As the dive progresses, the variation increases - I think moisture on the cell face but maybe I just have duff cells.)

OK. Re-read your post and I reckon the above is egg-sucking. However, I hope the last bit is of some use...

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SteveL

It looks like it is a VR3 problem

My Vr3 went back to DP for a software upgrade a few months ago - it came back and I swear the external connector was not working - I called up Dp and went through untold options upgrades pin changes but not good Sent the unit back to the UK from Australia at their recomendation and guess what they couldnt find a problem - not happy

I continuity checked the cable a number of times ant it tested OK - I told Dp this and they had the followiong comment

"We have run extensive checks on your VR3 and it works every time with our cables and cells, this points to your cable being the problem. Even if the continuity on the cable is OK there could still be a problem with it, there are other factors for the cable to work properly"

I checked the cells and ther was no problems so maybe when I get the unit back I will check it out - maybe its not your cells.... The varying outputs may be related to some resistance in the cable from corrosion???

Just thinking - hope this helps

Steve

ps I would like to know what "other factors" are

SteveL

It looks like it is a VR3 problem

My Vr3 went back to DP for a software upgrade a few months ago - it came back and I swear the external connector was not working - I called up Dp and went through untold options upgrades pin changes but not good Sent the unit back to the UK from Australia at their recomendation and guess what they couldnt find a problem - not happy

I continuity checked the cable a number of times ant it tested OK - I told Dp this and they had the followiong comment

"We have run extensive checks on your VR3 and it works every time with our cables and cells, this points to your cable being the problem. Even if the continuity on the cable is OK there could still be a problem with it, there are other factors for the cable to work properly"

I checked the cells and ther was no problems so maybe when I get the unit back I will check it out - maybe its not your cells.... The varying outputs may be related to some resistance in the cable from corrosion???

Just thinking - hope this helps

Steve

ps I would like to know what "other factors" are