Pelagian Diver Controlled CCR
Posted By Mark Ellyatt on 30 November 2006
Some would say that rebreathers are as predictable as having a monkey on your back. While that may be true with many units/monkeys, some have more refined habits and table manners!
Rebreather Lab, a company managed by Engineer and Dive Instructor Andreas Fritz who has been based in Koh Samui for the last 8 years. Andy contacted me some months back with a view to show-casing his new Pelagian Diver Controlled CCR and try to change my views on rebreather technology.
The Pelagian rebreather works similarly to the manual addition and constantly-flowing gas supply principles employed in the KISS rebreather unit already used extensively worldwide with a surprisingly low rate of users throwing sevens compared to the largely fully-electronic and therefore problematic competition. Diver controlled rebreather units employ a regulated and diver controlled metered valve system to introduce oxygen to the diver at a rate usually just below a divers' metabolic need. The constant but low flow rate helps users avoid the life threatening Hyperoxic tendencies associated with electronic CCR units while giving some minutes reparation time (depending on depth) before Hypoxia becomes a full blown swan-dive from the top of Nelsons Column. These so-called Diver-controlled CCR users are drilled/trained to maintain Po2 values constantly throughout their tuition courses as no automated addition systems are in place to 'protect' the complacent. In principle the need to add/maintain oxygen levels yourself seems very much more reliable in use than the plethora of electronic controls used in more complex but statistically more deadly fully electronic versions.
While the KISS units are designed to max out in the 110metre depth range by function of their gas supply regulators, the Pelagian differs in that no on-board component has been designed to limit achievable depth. In fact, the Pelagian's electronics are designed to work flooded and even without their protective cases so any depth related implosions won't be an immediate train crash. Apparently, Rebreather Lab has sold its metered valve system to many existing KISS users who desire to know what 150 metres depth feels like with only a half filled 3litre pony bottle for company...let me tell them - a 3 litre bottle used below 40metres is as safe as a crisp-packet parachute!
I have used many different types of rebreathers over the years and what I immediately noticed about the Pelagian is its obvious build quality and size. Andy and his team at Rebreather Lab have exhaustedly tried different materials during prototype evolutions finally using the veritable 'alien-spacecraft-hull' Acetal-co-polymer for the units core parts. Most divers would be aware of Delrin as a material of quality for such uses but Acetal-co-polymer is immeasurably superior and makes Delrin look like sugar glass in comparison. Delrin is an okay material, it is much cheaper to buy and easy to produce items from - this combined with its free-availability, makes it the ideal material of choice for the more 'mainstream' dive equipment manufacturers but it suffers from stress-cracking and as such was dropped from the material choice list for the Pelagian . The use of Acetal-co-polymer in the Pelagian's construction wouldn't impress company accountants but will please the end user both now and likely far into the future.
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