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November 2010    Download the Entire Issue (PDF) Available to the Public Vol. 25, No. 11   RSS Feed for Undercurrent Issues
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Will the Open Circuit Regulator Become Obsolete?

the next generation of rebreathers and training

from the November, 2010 issue of Undercurrent   Subscribe Now

In September 2007, DIVER magazine published one of my articles with the title tag line: In the Face of Growing Dive Fatalities is Modern Dive Technology Friend or Foe to Recreational Divers? A photo showed a Tech diver wearing double 100s on his back along with twin 80s slung under his arms. The diver was clearly overburdened with a ton of gear, the only way to provide the depth and bottom time necessary for the new breed of underwater explorers looking to push the recreational diving envelope. My hope was that readers would ponder the rationale behind that type of diving.

I also commented on the debut of several closed-circuit recreational rebreathers at the 2007 DEMA show in Orlando. This previously unwanted shallow water military child was pushing its way into mainstream sport diving. Rebreather manufacturer displays at DEMA had grown from two exhibitors a few years prior to an astounding 19 displays at that show, and 23 in Las Vegas in 2009.

Another first for that show was a new training agency that would conduct entry level training entirely on rebreathers. Thats right, no open circuit at all. All training, at all levels, is done only on rebreathers. Called RAID (the Recreational Association of International Rebreather Divers), their name clearly shows that they do not recognize normal dive equipment as part of their training curriculum (or the sport in general). When asked why RAID made such a dramatic change, Barry Coleman, founder, says typical scuba training with normal open circuit gear teaches many bad habits that a rebreather diver has to eventually unlearn. In his opinion it is much easier (and safer) to start from scratch on the rebreather.

While this makes sense, I admit to limited rebreather experience. I remember the dont even consider a rebreather mantra when I started my diving in the 80s. And, I have handled litigation involving recent rebreather fatalities, so I admit to being pre-conditioned to consider them dangerous.

The Fight against Rebreathers

Some people are so against rebreathers (some have lost loved ones in rebreather incidents) that they have embarked on personal crusades to have them condemned by the US Consumer Product Safety Commission. One is Stephanie Barrett, who lost her husband Robert to a rebreather accident in 2002. Her web site is a stark reminder that any dive fatality has far-reaching effect on those left behind.1

The Barrett lawsuit resulted in a defense verdict on behalf of the manufacturer, Ambient Pressure Diving after four years of hard fought legal battles2. Ambient is being sued in California regarding the death of another diver in 2006 using one of their units. And lawsuits against other manufacturers are brewing.

To understand the controversies in the rebreather community, simply GOOGLE rebreather diving and you find web sites and forums discussing rebreather fatalities ad nauseam as well as aggressive contrarian discussion. One expert wouldnt touch that unit for anything, but the next expert thinks the first guy is a loser! We have the rebreather community pushing the rebreather, families trying to ban them, and diving experts disagreeing on everything about them.

This on-line conjecture reminds me of the issues that were prevalent when Nitrox was introduced two decades ago, when the industry considered it the devils gas. During my Nitrox course in 1992, I was concerned when my instructor advised that we were not actually going to dive with Nitrox during the course. Afterwards, I realized that in-water training was irrelevant. Using Nitrox didnt actually change the dive itself, it only increased the allowable bottom time, so you use different tables. It was that simple. After that epiphany we agreed with several dive training agencies to provide insurance coverage for Nitrox training, and soon every training agency had a full blown Nitrox program. For many years, some industry insiders continued decrying the dangers of Nitrox and predicting lawsuits in staggering volume. The fuss over Nitrox was clearly the result of misinformation and the hesitation by the diving public to accept what was considered a radical change at the time. The rebreather, of course, is the next radical change and the Nitrox history is repeating itself.

We use large, heavy cylinders for our breathing gas because that is the best technology available. Modern rebreathers will change that. Not because they can store more gas in a smaller container, but because they allow us to use more of the O2 in the breathing gas, so we dont have to carry as much gas. Rebreathers are mechanically and electronically complicated when compared to the relatively simple open circuit scuba, but as a closed system they allow us to rebreathe the exhaled gas rather than exhaling it into the water, thereby using up more of the available oxygen. So, you get more bottom time with a smaller cylinder. (In an open circuit system, the amount of wasted oxygen increases as we go deeper, so we need multiple cylinders to extend our bottom time.) The practicality of the rebreather is only complicated because we can only rebreathe gas for so long before most of the oxygen is used up and we have to add new O2 (from a small storage cylinder). In older model rebreathers, O2 replenishment was done either by turning the gas on and off by cranking the valve on the cylinder or via a constant flow orifice allowing new O2 to dribble continually into the breathing loop. Not today. Rebreathers are flourishing because of modern electronics to control the monitoring and replenishment of O2 in the breathing loop.

The main complication, confirmed by quite a few lawsuits in progress, is that a reduced partial pressure of O2 in the breathing loop can cause you to blackout, which occurs when a diver rebreathes the gas until there is no longer enough O2 in it to keep you functioning. There is typically no warning. In fact, sudden unconsciousness is, unfortunately, a relatively common occurrence. Quite a few divers using current rebreather technology have died in recent years, so the inherent safety of these units continues to be under scrutiny.

This is where modern electronics makes the difference. If you can depend on the unit to monitor the partial pressure of O2 in the loop and maintain it at a level that keeps you functioning, then we should have a workable, safe system. Until the last couple of years, this type of O2 monitoring technol ogy was unavailable, too fragile, or too expensive for consumer rebreathers. Today, however, many newer units contain multiple O2 sensors and reliable electronic controls.

I must confess to taking a Draeger rebreather course years ago and decided that it wasnt for me. No O2 sensor, possibility of blackout, high maintenance requirements and the potential to blackout with absolutely no warning etc., kept me from taking the full plunge. I could not accept the risk that I, and my family, might have to deal with my death due to stupidity. Who wants to use equipment that has a high degree of probability that you will pass out while using it? My mother would not be able to accept that her professional, experienced, dive instructor son died using equipment known to act this way. Indeed, most rebreather litigation in progress now was initiated by families who cannot accept that concept. Theres a move to create a class action suit on the basis that rebreathers are an inherently dangerous or faulty product. That has to give a potential rebreather purchaser cause for hesitation.

However, rebreathers are looking more inviting today thanks to technological advancement. As I mentioned, RAID is already providing entry level training on rebreathers and if founder Barry Coleman has his way, all potential new divers are going to be told that the open circuit scuba is as archaic as a double hose regulator, not to mention quadruple 100s hanging off your body for deep dives. Maybe so. But many dive training agencies will have real issues with entry level rebreather divers!

For existing divers with a closet full of gear, one has to wonder if the price to switch makes sense. The same advancements in modern, low cost electronics are leading to the production of more affordable CCRs. The Poseidon Discovery costs about $6,800 but I believe it wont be too long before a new modern CCR will cost about as much as a top of the line open circuit scuba package. I have six aluminum 80s, three perfectly adequate late model regulators and a couple of high tech buoyancy systems. Will a new rebreather make that much difference to my diving? Will I sign my kids up for rebreather diving when I havent done it myself? Many questions, few answers, but that may be changing.

The Next Generation of Rebreathers

The unveiling of the new Poseidon Discovery rebreather last year signaled the beginning of the recreational rebreather marketing onslaught! The Discovery is advertised as a plug and play unit and the main module is described as dishwasher safe. Yes, you can clean the main module in your dishwasher! It would be hard to argue that an entry level diver would have more difficulty dealing with this unit than with a normal open circuit scuba tank and regulator setup. (Remember all those students who put their regulators on upside down and/or backwards?) Other than the requirement for a charged battery, its advertised as being as reliable as open circuit gear. Certainly, failed rebreather electronics may have more serious consequences than a failed cell phone, but we rely on electronics for driving and flying, so its not much of a stretch to depend on an electronic scuba system. Indeed, many dive accessories (wireless pressure sending modules, computers, and heads up mask displays etc.) are already commonplace and apparently dependable. Heres some eye-opening (edited) comments from the Poseidon web site:

The diving is simple. Open the tank valves, wet the switch on the back of the display, wait for the systems check and off you go. Forget about everything you ever heard about PO2, scrubber life and oxygen cells. The system will handle all that. You will inhale warm and humid air with a gas mixture optimized for your depth. You will stay warm longer, you will dehydrate less and your body will experience less decompression stress . . . You need four consumables: oxygen; air; pre-packed canister (your dealer can provide) and a charged battery, which you can charge at home before diving. The cost per diving hour is no higher than for ordinary scuba diving, but the added experience is priceless . . . Nothing is smaller, lighter, and more user-friendly. Then nobody has ever built a rebreather for sport divers before. At 33 lbs. fully loaded, the unit weighs even less than most scuba tanks. Weighing only 18 lbs. without tanks and absorbent, it is perfect for travelling . . . The Discovery is fully automatic. Technology handles everything . . . The mouthpiece is unique. Not only because you can select between rebreather mode (closed circuit) and open circuit by simply turning the lever, but also because of its simplicity. Poseidon has used a regulator with an impressive track record, used by military and rescue divers all over the world and NASAs backup-divers . . . A small LED and a vibrator to make the diver look at the display for messages of importance is built into the mouthpiece . . . The Discovery control system is unique. From the continuous calibration of sensors enabling you to trust the reading of all sensors, to the resource management system that measures your gas consumption to ensure that the available gas is always enough to reach the surface. The control system measures everything from battery capacity to tank pressure, from oxygen level to atmospheric pressure and depth. It injects precise amounts of gas to keep the right mixture for every depth.

The Forget about everything you ever heard about PO2, scrubber life and oxygen cells. The system will handle all that comment summarizes the marketing pressure we will face. Heaven help them, and their insurers, if people start dying regularly while using this unit!

In Part 2 of this article, we will interview two industry experts about rebreathers, discuss additional dangers of rebreather use as well as the potential conflict between open circuit divers and rebreather divers in the real world.

The author, Peter Meyer, is the senior vice president of a major international insurance brokerage firm and has been a leading consultant for the dive industry since 1988. He provides risk management advice and insurance to dive training agencies, retail dive facilities, dive vessel operators and dive equipment manufacturers. He has owned and operated retail dive facilities, liveaboard dive charter vessels, and has taught recreational diving at all levels. He lives in Vancouver, British Columbia.

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  1. See: www.inspiration-rebreather-fatalities.com/pages/5/index.htm
  2. See www.verdictsearch.com/index.jsp?do=news&rep=recent&art=165530

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