Is this IT?!

[padiscubapro]

OK Joe, spill the beans, how do you get 92% O2 to register as 100% in the electronics? By pressurizing the head past 1 ata?

And how could I have gotten higher than 95% in places like Ambon Indonesia, where I'm pretty sure they only had a PSA system? My sensors were calibrated to good O2 back home and came back down to 20+% in air after cal with the O2 in Ambon, and the O2 there looked like about 97% on my 2dry at sea level. How common is an extra argon removal stage on PSA systems?

if its o2 by a psa system it CAN'T be greater than 95.5%, unless it has a second PSA system designed to remove argon then its 99.9%.. if you were reading higher than this the display is either not calibrated properly or the sensors are not linear..

look on rb world for an article Accurate po2 calibration..

a secondary argon removal system is not that common since it nearly doubles the cost of the system.. Its generally only used in aplications that demand the higher purity..

 

[Bryan]

Does anyone know the SRP on this, including training?

 

[silent running]

if its o2 by a psa system it CAN'T be greater than 95.5%, unless it has a second PSA system designed to remove argon then its 99.9%.. if you were reading higher than this the display is either not calibrated properly or the sensors are not linear..

look on rb world for an article Accurate po2 calibration..

a secondary argon removal system is not that common since it nearly doubles the cost of the system.. Its generally only used in aplications that demand the higher purity..

Yes Joe, I've read the article before, the table of back pressures for decreasing O2 % is very helpful. But I brought up the fact that the MK6 won't allow a surface cal with less than 99% because I doubt many beginning CCR divers who buy the MK6 will know how or want to put together and travel with the hardware necessary to calibrate with a pressurized head. I'm sure this will also be discouraged by their instructors, if the student is even aware enough to ask about encountering low purity O2 in other parts of the world, as obviously the mnf doesn't want the users to use lower % O2 based on their opinion about the safety issue of argon in the loop when using low purity O2.

And, it's my understanding that the unit continuously calibrates, so there's a chance that even if one did successfully cal the unit with lower O2% using the necessary back pressure hardware, it may invalidate the surface cal as soon as the unit is put back together, turned on and fires the solenoid even once at the surface...

 

[Meng_Tze]

I scanned the white paper on the Poseidon site and this is my understanding of how they have circumvented this issue: When starting up a small amount of dil (air) is injected across the primary and secondary cell. This gives you a dual reference point for 'low O2' mix. Then the high O2 is injected over the cells. With a reference table you can calculate what that value should be on almost any gas. It is what I use on my checklist for my RB (I know I forgot to set the rounding factor to 1-2 digits... ).

 

[ronski101]

This appears to be a step in the right direction. I would love to have a rebreather but it needs to fit the following cryteria for me:
1. Not much more expensive than the present rec stuff available
2. At least as dependable as the present stuff
3. As easy to use as the present stuff
4. Similar maintenance requirements.
5. Redundencies & fool proof
Well, I am not holding my breath...................

 

[Jill Heinerth]

I found the recreational rebreather of my dreams for $89.99

 

[Thalassamania]

I found the recreational rebreather of my dreams for $89.99

Here's one for about ten bucks more: