CW Diving

WARNING:

Diving in contaminated water is very hazardous. It should not be attempted without through training and proper equipment.

DESCO recommends using a free flow style diving helmet with a double exhaust valve, mated to an appropriate drysuit, for contaminated water diving operations.

Demand vs. free flow.

Our intent is to point out the clear advantage our helmet has in performing in the worst chemical, biological, and nuclear contamination environments.

In contaminated diving situations doing away with the demand feature and going "free flow" is the logical and safest course. The DESCO Air Hat is the preferred helmet for contaminated water diving. The “free flow” through the helmet assures constant overpressure is maintained. Having air constantly passing out of the exhaust valve greatly reduces the potential for contaminates to leak back into the helmet. This feature is especially desirable when diving in highly caustic or dangerous environments such as fuel tanks, acid storage tanks, or nuclear fuel transfer pools.

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Increasingly, divers are asked to work in contaminated environments. Harbors, urban rivers, sewage treatment plants, and nuclear power stations are just a few places a diver may find a jobsite. A demand helmet suffers from a susceptibility to a basic law of physics. Operation of the demand valve will cause fluctuation in the pressure differential and potentially permit leak back of contaminated water through the exhaust valve. Double exhausts reduce the chances of contaminated water leaking back into the helmet. Stacking additional exhaust valves will further reduce the likelihood of leak back but this adds more working parts to the helmet. This does not change the fact that constant outflow is the best way mitigate leak back.

Another consideration is if leak back occurs on a free flow helmet the leaked water will normally collect in the bib, neck dam, or body of the dry suit. On a demand helmet the water will be leaked back into the oral/nasal where the diver can ingest it through inhalation or swallowing.

The most important advantage the DESCO Air Hat has over a demand helmet is the free flow design maintains a constant overpressure and minimizes the potential for leak back. It is the standard helmet for use in inland contaminated diving.

The U.S. Navy has issued a revised U.S. Navy Contaminated Water Diving Guidelines Document

as of January 15, 2008.

Click here for a full PDF of the current

U.S. Navy Contaminated Water Diving Guidelines on the Supervisor of Salvage website.

You will need Adobe Reader to access file.

Additional websites with information pages on contaminated water diving:

NOAA Diving Program: Contaminated Water Diving Reports

OSHA: Hazardous waste operations and emergency response. - 1910.120

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