A Different Approach to O2 Control
/The Earth is not flat and the 2-cell approach probably works.
When it was first introduced the Discovery MK VI Rebreather by Poseidon was referred to as a radical and unique design and caught a lot of people's attention. When Cis-Lunar launched it´s MK 5 Rebreather back in 1998 it became an instant sensation in the diving community. For the first time ever, a state-of-the art fully automatic breathing apparatus was available for long dives and built with the safety and ruggedness needed for advanced cave exploration and technical diving. And we dare say, few have matched the performance of the MK V (not withstanding the market leader in ruggedness developed by Leon Scamahorn and his Megladon). The new fully automatic MK VI Discovery Rebreather was designed to give sport divers the ultimate diving experience without all the technical complications. Forget everything you might have heard about PO2, scrubber life and oxygen cells - this design challenged all traditional philosophies on Rebreather infrastructure. The compact combined mouthpiece made going to open circuit as easy as just flipping a switch and acts as an ADV. A feature many of the newer models have now adopted. Forget about multiple sensors and the confusing complexities of voting logic. This unit offered continuous calibration and real time monitoring of oxygen and CO2 issues. Post dive procedures were as simple and safe as open circuit (well almost). It was small, functional and very cool - and most importantly drove many of the other CCR manufacturers to employ the same kind of technology we see in most all rebreathers today.
Okay - that is a great selling job. But let's talk about the design. Bill Stone has to be, by far one of the brightest most ingenious designers in the world and a very dynamic individual - just check him out on ‘Ted Talks’. In addition to being featured in National Geographic his accomplishments can be found recorded in any reputable magazine or journal in print. His old company Cis-Lunar (which literally translates into "on this side of the moon" or "not beyond the moon") was only the beginning and the website for his company, Stone Aerospace, provided an itinerary of the most advanced exploratory equipment used in inner and outer space.
The MKVI control system allowed continuous calibration of sensors enabling the diver to always trust the reading of all sensors
But does Dr. Stone's reputation and dog and pony show distract us from making educated and unemotional decisions about this technology. Blind faith - we usually accept it when we a) want to believe something is true and b) to lazy or uneducated (or both) to challenge it. Don't get us wrong - when this unit came out it had me all goose-pimply and excited but let's analyze the MK VI CCR and the 2 cell approach with the due process it deserves. Again this article is NOT about the MK VI from Poseidon/Cis-Lunar. It is about entertaining new theories in Rebreather technology (well any new technology for that matter) with a fair and objective mindset.
There is not enough Gigabytes on my server to present all the issues at hand to thoroughly discuss this technology nor do I purport to be an informed expert on this subject matter. But I do have fun with it none-the-less. Let's start with the 'White Papers' drafted on this technology. It reads very well - too well in fact. A professionally written, academically sound scientific thesis on the 2-cell approach to CCR designs. This document wins - right up until then end, where it then turns into a brochure for Poseidon. Shame really.
Why was the MK VI control system unique? Poseidon alleged that the continuous calibration of sensors enabled you to always trust the reading of all sensors and the resource management system measures your gas consumption throughout the dive and guided you to ensure that the available gas always was enough to reach the surface. These vital electronics were covered in oil to ensure there was maximized protection {theoretically}. The control system measured everything from battery capacity to tank pressure, from oxygen level to atmospheric pressure and depth. Subsequently it injected precise amounts of gas to keep the right mixture for every depth. We have to admit it's simplicity was attractive and tended to make you want to believe this was solidly developed technology.
I like simplicity. Surfing the Rebreather sites I found a lot of experienced divers liking this new 2-cell stuff. The next generation Poseidon, “SE7EN”, or Generation 7 electronics open up endless possibilities for interaction, accessories and apps and as advertised on their website: “Entirely new internal hardware driven by a new generation of firmware makes the SE7EN faster, flexible and reliable in any diving environment”. Now it seems all of the leading CCR makers have followed the lead by adopting most of the technology introduced in the MKVI although the two-cell approach still hangs for consideration.
The Se7en or Gerneration 7, Developed from the world’s first recreational rebreather, the legendary Poseidon MKVI.
The debates go on and it appears true; the Earth is not flat and the 2-cell approach probably works.
~Safe Diving