Scrubber duration in warm water

[Zeus Faber]

Hello,

Some of these data are published....

eg http://bit.do/sorb

Simon,

Having used PSCR type rebreather for a while I would have expected to compare Spherasorb with Sofnolime CD (4-8 mesh) which has a similar size. Even form the Layman point of view (who I am) I would never thought that 797 and Spherasorb could have the same duration. A Spherasorb pellet is twice if not three time the size of 797. Of course your study is very important. You were a real Mith buster with that.
ATM I'm using a CCR and for less demanding dives (up to 120 minutes, 14°c on the bottom and > 20°C in deco) I still prefer Spherasorb for its more pleasant WOB. For longer dives I use 797 to stay safe.

Is there any medical test a ccr diver could undergo to exactly calculate his O2 consumption and CO2 production under execrcise?

Thank you in advance.

 

[Dr Simon Mitchell]

Having used PSCR type rebreather for a while I would have expected to compare Spherasorb with Sofnolime CD (4-8 mesh) which has a similar size. Even form the Layman point of view (who I am) I would never thought that 797 and Spherasorb could have the same duration.

Hello Zeus,

A number of people have made similar comments, but you do not have to look far on the internet to find divers reporting that they use spherasorb and commenting favourably on its duration. Some have even claimed it lasts longer than 797, and frequently quote the Russian study which we cite in the paper. That study reported that spherasorb lasts 30% longer than sofnolime 797! Prior to our study that was the only relevant independent data in the public domain, but we did not believe it (for the same reasons you specify). That is why we did the study and I believe ours is the correct result. The Russian study was never published in a scientific journal.

Is there any medical test a ccr diver could undergo to exactly calculate his O2 consumption and CO2 production under execrcise?

These parameters can be measured in a properly equipped exercise / respiratory function laboratory. That is how we derived the ventilation and CO2 addition parameters for our experiments. You can be exercised at precisely measured levels on an electronically braked exercise bike, and the oxygen consumption and CO2 production are measured at the different exercise levels. Unfortunately you need access to such a lab.

Having said all that, you can make some crude estimates of your own starting with the assumption that 1 MET represents approximately 3.5 ml /kg / min of oxygen consumption. You also need to make assumptions about what different activities in diving represent in METs.

Simon M

 

[doctormike]

I know you will be interested, but I cannot discuss the reasons we were doing these experiments at this stage. Once the papers are published we will organise early release (as we did with the one I have linked to above) and make them available for everyone quickly.

Simon M

Thanks, this is very interesting and helpful..