O2 sensor question

RobPot · 31st July 2006, 09:28

Is there a Noddy's/Idiot's guiode to oxygen sensors anywhere - did a quick search here but nothing leaps out apart from Mark's problems with his sensors and Kevin's splendid comment:

Quote:

Last Point: eCCR's are NOT TOASTERS - these things are Life Support Devices, which means that you need to take them more seriously than you would your iPod.

Did a quick check this morning with my Classic KISS and with the Shearwater reading 0.90 PPO2 I get millivolt readings from the three cells of between 45 and 47mv - sound about right?
But with Natasha's KISS and the VR3 to a P-ported cell yesterday we only got about 23.7mv with 1.0 and a 'Cell low' warning. So I guess the cell is probably dodgy, but is the VR3 reliable in this measurement?
And the other cells in her KISS all react very slowly - is this a sign of more current limiting?
(Cells are all R22-BUDs and less than three months old).

Any advice gratefully received.
Thanks

Robert

Allan_o · 31st July 2006, 10:10

hi there.

Try this book.
it helped me for better understanding...

www.diveriteexpress.com/gas/analyzervan202.shtml#oxygen

Regards Allan

jhaaja · 31st July 2006, 10:30

Quote: (Originally Posted by RobPot)

Is there a Noddy's/Idiot's guiode to oxygen sensors anywhere - did a quick search here but nothing leaps out apart from Mark's problems with his sensors and Kevin's splendid comment:

Did a quick check this morning with my Classic KISS and with the Shearwater reading 0.90 PPO2 I get millivolt readings from the three cells of between 45 and 47mv - sound about right?
But with Natasha's KISS and the VR3 to a P-ported cell yesterday we only got about 23.7mv with 1.0 and a 'Cell low' warning. So I guess the cell is probably dodgy, but is the VR3 reliable in this measurement?
And the other cells in her KISS all react very slowly - is this a sign of more current limiting?
(Cells are all R22-BUDs and less than three months old).

Any advice gratefully received.
Thanks

Robert

Sounds like the cells have been bad from the factory. I had one die in less than one month. Now it is back at AP and I should get a new one soon.

For current limitation you should try it with pure O2 in 6-8 meters and see how high the cell can go.

JH

Mark Gregus · 31st July 2006, 19:39

Robert,

Take the sensors out of your unit and test them independently. They should read 8.5 - 14 Mv each. It sounds like you have a sensor that has a low output. As far as the sensors reacting slowly, make sure that there is no condinsation built up on the front of the sensor this may affect the speed of response. If your sensors are less than 12 months old they should be covered under warranty. I would contact Teledyne or Oxy Cheq for further information.

Regards,
Mark Gregus
Diving Sales Manager
Analytical Industries Inc
gregusm@aii1.com

Gilles · 31st July 2006, 22:21

Robert;

I'm unsure if you're using R22D's or not. In case you are, they should read between 9-13 mv in air. Below 9, then keep a close eye.

Whether it is another type of sensor or not, the following holds.

Divide the purity of your O2 (e.g. 97%) with the O2 purity of air and you will get a multiplication factor (e.g. .97/.209 = 4.64). Ideally, your sensors in O2 should read MVair x 4.64.

Or another way is to divide the O2 mV by the multiplication factor (make it a division factor) and see if your air mV is correct (if your actual air mV is above this number then

).

Also I have found more reliable performance by using post-dive calibrations on my Meg (sensors are calibrated in the damp state they normally operate in). The data I have posted in http://www.rebreatherworld.com/megal...onitoring.html remains valid to this day. Hope this helps.

31st July 2006, 09:28	#1 (permalink)
RobPot Rebreather World Writer Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: May 2005 Location: Portishead - Gateway to the South West Posts: 174	O2 sensor question Is there a Noddy's/Idiot's guiode to oxygen sensors anywhere - did a quick search here but nothing leaps out apart from Mark's problems with his sensors and Kevin's splendid comment: Quote: Last Point: eCCR's are NOT TOASTERS - these things are Life Support Devices, which means that you need to take them more seriously than you would your iPod. Did a quick check this morning with my Classic KISS and with the Shearwater reading 0.90 PPO2 I get millivolt readings from the three cells of between 45 and 47mv - sound about right? But with Natasha's KISS and the VR3 to a P-ported cell yesterday we only got about 23.7mv with 1.0 and a 'Cell low' warning. So I guess the cell is probably dodgy, but is the VR3 reliable in this measurement? And the other cells in her KISS all react very slowly - is this a sign of more current limiting? (Cells are all R22-BUDs and less than three months old). Any advice gratefully received. Thanks Robert
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31st July 2006, 10:10	#2 (permalink)
Allan_o New Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Dec 2005 Location: Copenhagen Denmark Posts: 80	Re: O2 sensor question hi there. Try this book. it helped me for better understanding... www.diveriteexpress.com/gas/analyzervan202.shtml#oxygen Regards Allan
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31st July 2006, 10:30	#3 (permalink)
jhaaja Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Mar 2005 Location: Finland Posts: 867	Re: O2 sensor question Quote: (Originally Posted by RobPot) Is there a Noddy's/Idiot's guiode to oxygen sensors anywhere - did a quick search here but nothing leaps out apart from Mark's problems with his sensors and Kevin's splendid comment: Did a quick check this morning with my Classic KISS and with the Shearwater reading 0.90 PPO2 I get millivolt readings from the three cells of between 45 and 47mv - sound about right? But with Natasha's KISS and the VR3 to a P-ported cell yesterday we only got about 23.7mv with 1.0 and a 'Cell low' warning. So I guess the cell is probably dodgy, but is the VR3 reliable in this measurement? And the other cells in her KISS all react very slowly - is this a sign of more current limiting? (Cells are all R22-BUDs and less than three months old). Any advice gratefully received. Thanks Robert Sounds like the cells have been bad from the factory. I had one die in less than one month. Now it is back at AP and I should get a new one soon. For current limitation you should try it with pure O2 in 6-8 meters and see how high the cell can go. JH
(Offline)

31st July 2006, 19:39	#4 (permalink)
Mark Gregus New Member Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Jun 2006 Location: California, USA Posts: 4	Re: O2 sensor question Robert, Take the sensors out of your unit and test them independently. They should read 8.5 - 14 Mv each. It sounds like you have a sensor that has a low output. As far as the sensors reacting slowly, make sure that there is no condinsation built up on the front of the sensor this may affect the speed of response. If your sensors are less than 12 months old they should be covered under warranty. I would contact Teledyne or Oxy Cheq for further information. Regards, Mark Gregus Diving Sales Manager Analytical Industries Inc gregusm@aii1.com __________________ Mark Gregus Diving Sales Manager Analytical Industries Inc. 909 392 6900 email: gregusm@aii1.com
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31st July 2006, 22:21	#5 (permalink)
Gilles Worship the feminine Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Den Haag (Netherlands) Posts: 761	Re: O2 sensor question Robert; I'm unsure if you're using R22D's or not. In case you are, they should read between 9-13 mv in air. Below 9, then keep a close eye. Whether it is another type of sensor or not, the following holds. Divide the purity of your O2 (e.g. 97%) with the O2 purity of air and you will get a multiplication factor (e.g. .97/.209 = 4.64). Ideally, your sensors in O2 should read MVair x 4.64. Or another way is to divide the O2 mV by the multiplication factor (make it a division factor) and see if your air mV is correct (if your actual air mV is above this number then ). Also I have found more reliable performance by using post-dive calibrations on my Meg (sensors are calibrated in the damp state they normally operate in). The data I have posted in http://www.rebreatherworld.com/megal...onitoring.html remains valid to this day. Hope this helps. __________________ Gilles http://www.dirrebreather.com Last edited by Gilles : 1st August 2006 at 04:27.
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