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June 2006 Vol. 32, No. 6   RSS Feed for Undercurrent Issues
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Killer Regulators

from the June, 2006 issue of Undercurrent   Subscribe Now

Divers are risking their lives by failing to maintain and service their regulators adequately, according to a new report from Britain’s Health and Safety Executive (HSE). Almost half the regulators tested during a three-year HSE investigation into diving deaths would not pass the European EN250 standard for regulator performance due to “lack of maintenance, servicing and cleaning, and incorrect setup.” More than a quarter of the fatalities could be directly attributed to equipment faults, primarily in regulators.

The EN250 standard defines limits of breathing resistance — the work the diver must do to inhale and exhale. All regulators sold in the EU must pass this standard. The regulator is set up in an ANSTI machine, which simulates different diver work rates in breaths per minute, depths, cylinder supply pressure, and water temperature, all of which affect performance. When a dive computer was recovered from an accident, the dive profile was used to reconstruct the incident in the ANSTI machine.

HSE offers free testing for coroners and police services, so equipment associated with deaths can be tested to the conditions of the fatality. Excluding rebreather incidents, faulty regulators were “confidently identified as the probable cause” in 12 of 46 deaths.

Altogether, 60 regulators were tested, including some from the buddies of the deceased. Of these, 28 — almost half — failed the European standard test, whether or not they were directly implicated in the demise of the diver. In several of the fatalities, people were diving to the depth limits of their training, but also close to and beyond the performance limits of the equipment they were using. Most divers know that regulators become harder to breathe the deeper they go, but few know the tested limits of their regulator, which is never provided by the manufacturer.

“If a regulator becomes very hard to breathe, the solution is to stay calm and ascend,” said Nick Bailey of the Health and Safety Laboratory, where the testing has been taking place. “The problem may ease during the ascent, but the regulator should not be dived again until it has been serviced professionally… It is always wise to test-dive a newly serviced regulator in a pool or in shallow water, as current bench-test servicing cannot take into account performance under pressure.”

Octopus regulators are not tested simultaneously with main regulators, which is how they would be used in an emergency. The HSE believes there is a strong case for changing the standard to include a simulation of buddy breathing. In five of the cases it investigated for this report, a diver died after sharing air from the same first stage.

excerpted from Dive Magazine, U.K.

P.S. In the United States, there are no industry-wide standards for regulators. While DAN (Divers Alert Network) conducts an annual study of U.S. diving fatalities, it focuses on the medical causes of the death, not diver error or equipment. There is no systematic study of equipment used in a fatality. DAN, however, routinely asks whether equipment problems were involved in each case, but the equipment may have never been tested. DAN chief executive officer Dan Orr told Undercurrent that equipment problems are rarely found to be the cause of death, though they may precipitate a problem such as a fatal heart attack. When dive gear is involved, says Orr, problems generally are caused by poor maintenance, self-repair, lack of familiarity with the equipment, or operator error, such as forgetting to hook up an inflator hose.

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