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January 2008    Download the Entire Issue (PDF) Available to the Public Vol. 23, No. 1   RSS Feed for Undercurrent Issues
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Out of Air? Try Your BCD

what the agencies won’t tell you about secondary air sources

from the January, 2008 issue of Undercurrent   Subscribe Now

No diver should ever run out of air, but it still happens with alarming frequency. Panicky ascents can lead to embolisms, blackouts and other primary causes of diver deaths. But there is a technique that can provide a few additional breaths – just enough to locate a buddy or start a controlled swimming ascent. It involves breathing air directly from your BCD. It’s tricky to master, but when all else fails, it might save your life – or your buddy’s.

Even if you suck your tank bone dry
at depth, you can still breathe the
residual air in your BCD

Say you’re 100 feet down with two buddies and both come to you out of air. If you’re experienced and alert, you could pass your primary second stage to one buddy and give your octopus to the second. But what about you? Begin a slow ascent. Valve fresh air into your buoyancy compensator with your BCD’s inflator hose and breathe through your oral inflator mouthpiece. Instead of free-ascending with no air, you’ll have a few breaths of air from your BCD as you rise, allowing you to make a slower and safer ascent.

You may have never heard of BCD breathing. You see, no commercial training agency teaches this technique at any level. In fact, since we first reported on it several years back, the industry seems to have closed ranks against it, even though it’s been successfully tested in various predicaments.

We’re hardly advocating breathing the air remaining in a BCD as standard practice. It’s only as a last resort. Even if you suck your tank dry at depth, you can get some air through your regulator as you ascend and the air in your tank expands. But once your tank is bone dry, you’ll still have residual air in your BCD, or at least in your inflator hose. If you added air with your power inflator, it will be pure and contain 21 percent oxygen. If you orally inflated your BCD, it will still contain at least 16 percent oxygen.

Breathing Cycles

Bear in mind that air in your BCD will also expand as you rise. If you put your BCD mouthpiece in your mouth and keep trying to inhale and exhale while you rise, your air volume will soon increase enough to provide a breath.

Studies conducted by the late Al Pierce of the YMCA concluded that you can exhale into your BCD and keep rebreathing the same air 13 times or more without becoming overly hungry for fresh air. (After all, exhaled air is good enough for artificial respiration.) TDI/SDI founder Bret Gilliam told Undercurrent of a commercial diver whose hand got trapped under a pipe. To conserve air, he orally inflated his early edition flotation vest and began breathing from it until the carbon dioxide rose to an uncomfortable level. Then he switched back to his regulator, caught his breath with clean air from the tank, vented the vest and started the cycle again. After an hour in 50 feet of water, his tank was down to 100 psi and he was ready to amputate his fingers to free himself when another member of his dive team came by and started buddy breathing with him.

Why Don’t Agencies Teach This?

It’s partly due to the industry’s resistance to change. Years ago, when early BCDs could be inflated with carbondioxide cartridges, there was a concern about breathing residual carbon dioxide. A more current objection is the possibility of respiratory infection from bacteria inside the BCD. Dennis Pulley, director of training at Scuba Schools International, cited this as the primary reason why SSI doesn’t teach BCD breathing at any level.

However, BCDs used for training can be disinfected with solutions readily available in dive shops. Or you can use benzalkonium chloride, available at drug stores under the brand name Zephiran chloride. Besides, antibiotics cure respiratory infections. Drowning is forever.

Nevertheless, the industry remains set in its ways. For instance, today’s Aqua Lung BCD owner’s manuals still carry the warning, “DO NOT inhale from your oral inflator. The BC may contain harmful contaminants or gasses, which could cause suffocation or injury.” When we discussed this with Tom Phillipp, Aqua Lung’s product manager for BCDs, he conceded that it probably needs to be updated.

The biggest objection is that divers will need to master new skills and perhaps relearn some old ones. For instance, you must be able to clear the ounce or so of water from your inflator hose mouthpiece without choking. Joel Silverstein, chief operating officer of Scuba Training and Technology Inc., points out that breathing in and out of a BCD creates a closed circuit that can cause carbon-dioxide buildup and lead to shallow water blackout. Also, your BCD will become more buoyant as you rise, leading to a possible uncontrolled ascent. Both dangers can be averted by exhaling through your nose, but this creates other challenges. First, unless your mask has a purge valve, it might leak. Second, by exhaling you’re emptying your air supply and decreasing your buoyancy – perhaps to the point of being overweighted.

Gilliam, who now advises the industry on training procedures, told Undercurrent he considers BCD breathing “a viable independent self-rescue technique.” Yet, he says, “There is no such drill in any entry level course worldwide.” As an instructor, he’s noticed that in emergency situations, many divers adopt a “rigid flight posture,” visibly stiffening in the water column, which prevents them from handling such tasks.

Silverstein calls the concept of BCD breathing a “radical technique” that is not part of any formal training curriculum. His concern is that most divers just don’t have what it takes to perform this skill without panicking. “The average diver makes fewer than 10 dives a year.” He’s convinced that divers who don’t practice the skill continuously “won’t know how to do it and will kill themselves.”

These are valid considerations, but does it make sense for certified divers to not even be exposed to this proven technique for handling out-of-air situations or equipment malfunctions?

PADI has recommended options for low/out of air situations, in order of priority. 1) Make a normal ascent if your tank isn’t completely empty. 2) Ascend using an alternate air source (redundant supply or buddy’s octopus). 3) Execute a controlled emergency swimming ascent. 4) Buddy-breathe with a single regulator supplied by another diver. 5) Make a buoyant emergency ascent.

However, isn’t a controlled emergency ascent or a buoyant emergency ascent safer if you have a few breaths of air from your BCD? Knowing you’ve got at least one more ace up your sleeve might help keep you cool as you weigh your options. Hopefully, you’ll get things under control before you ever need to use your BCD as an alternate air source. But it’s there if you need it.

-- Larry Clinton, Jr.

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