http://dsc.discovery.com/news/briefs/20050...ishbreathe.html


June 24, 2005— An Israeli mechanical engineer and scuba diver has invented a device that could have people breathing under water like fish.

The new Tankless Breathing system extracts air from water, similar to a set of gills, and could one day be used supply air to divers, submarine crews, and even undersea human habitats.

"If mankind decides to build underwater habitats, I'm confident that this method will be the source of air," said inventor Alan Bodner, founder of Like-A-Fish Technologies.

Current methods for breathing under water vary from tanks of compressed air for divers to systems inside nuclear submarines that provide air by chemically separating oxygen from water molecules.

But these solutions have their limitations. Compressed air tanks are heavy, limit the diver's time under the water and change the diver's balance as the tank empties.

Chemically separating oxygen from water molecules — a process known as electrolysis and used in nuclear submarines and on the International Space Station — is expensive and requires a great deal of energy to operate.

Conventional submarines rely on air tanks and surface frequently to refill them.

Bodner's patent-pending apparatus capitalizes on nature. It turns out that normal atmospheric pressure forces tiny amounts of air into seawater. Reversing that pressure releases the dissolved air from the liquid.

To accomplish this, the device uses a centrifuge that, when rotating rapidly, reduces the pressure inside a sealed chamber containing sea water.

As the liquid air separates from the water, it automatically converts back to its gaseous state and becomes breathable.

"I think this approach will be very successful if it is used in submarines," said Frans Klut, a former Dutch naval officer who served for 34 years and conducted a variety of studies on underwater diving equipment and defense techniques.

"The only point is that you have to circulate a lot of water to have enough air to breathe," Klut said.

Only 1.5 percent of every liter of water is liquefied air. To accommodate the breathing needs of an average human male, Bodner's system must circulate 200 to 2,000 liters per minute, depending on the specific need.

For a diving system, that would require an electric motor, a pump, a cylinder, a centrifuge, air bag, breathing hose and batteries, the total of which would weigh less than 30 pounds.

That compares to an air tank system that can weigh up to 42 pounds.

And while condensing this all into a small, lightweight vest for divers should be feasible in a few years, getting the technology to work in a submarine is a goal Bodner has his sights set on first.

The breathing system could be tied to a sub's propulsion system, where a high capacity of water flow occurs and large amounts of air could be extracted.

Bodner has already met with diving manufactures and the Israeli navy, and is currently looking for private investors.