Pelagian Diver Controlled CCR
Posted By Mark Ellyatt on 30 November 2006
Andy gave me a brief tour of the factory and explained the how's and whys behind the unit's design then set about building up a rebreather completely from the parts bin to fit me. Virtually all the components are built from scratch in-house, only the rebreather hoses are outsourced from a company in the United States. The Pelagian is supplied in kit form, the user expected to add things like pressure gauges, a couple of oxygen analyser cells plus a buoyancy wing and back-plate plus a few other odds and sods. Completely assembled with the twin 2.6 litre dive tanks and 2.85kg's of Carbon Dioxide absorbent the unit weighs about the same as 10litre twin-set. The company states a maximum in-water time of 4 hours in cold water and 6 hours in warm - somewhat longer than twin 10's. Unit assembled I jumped into the pool that adjoins the workshop and classroom facilities at Rebreather Lab HQ, very Tracey Island 'esque' really. I'm aware of the number of fatalities of CCR users in a shallow swimming pool and to make sure I didn't swell those numbers stared at the po2 displays like they were showing my winning lottery numbers! As luck would have it the pool session was drama free and I was impressed with the work of breathing as I changed body position from face down swimming to surface gazing. I thought maintaining a constant partial pressure of oxygen (set point) would mean constant fiddling on such a unit in the shallows but the effort of adjusting flow-rates became minimal with just tiny changes to the metered valve necessary after only 30 minutes of practice drills. After just an hour in the pool I felt confident enough to take the unit into the proper sea to stretch both its and my legs A scheduled day trip to the nearby island of Koh Tao was booked with the normal 1 hour speedboat trip looking ominous and likely to double with the storm sized winds that were buffeting the area. Getting up at 6.30am was bad enough but within an hour we were all bouncing up and down like Tourettes sufferers on pogo sticks wedged into the triple-engined speedboat driven without let-up through the walls of green water gut wrenchingly.
The Pelagian has an inbuilt auto-diluent-valve (ADV) which the unit designers have tailored to fit neatly into the scrubber lid itself. The ADV's position in the lid means any fresh gas added is blown across the oxygen sensors in an attempt to rid them of oxygen-value-altering water droplets - a problem with some units but not this one. Dropping over the side into angry seas was a bit of a chore and we aimed to head down as quick as possible. Descending so fast normally would collapse a rebreather's breathing bags unless it has an ADV fitted - as it did, no problem. I was pleased to be able to breathe comfortably during the frantic descent. Hitting 20 metres at the Chumphon Pinnacle dive site meant instant tranquillity and gave time to tinker with the oxygen addition valve to get the set point up to 1 bar. This done I started going through practise drills while Iona the photographer snapped away like a manic Japanese tourist. Closing the mouthpiece was easy enough and switching to a functioning bail-out regulator is always reassuring. Andy from Rebreather Lab was swimming close by wearing his newly acquired and almost vintage looking Cis Lunar unit occasionally prompting me to respond to a pretend problem. Back in the day the CIS was the Lamborghini Gallardo of rebreathers, though a decade on it now resembled a MK 2 Ford Escort. Having dived both units, the young upstart Pelagian was clearly my favourite - much lighter to wear and far easier to breathe from. Funnily enough the Pelagian fitted into my travelling backpack so would be ideally suited for holidaying with - the Cis Lunar would struggle to fit into a 40 foot container!
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