New U.S. Navy Rebreather Reduces Helium Loss

The U.S. Office of Naval Research has developed a new rebreather system, the MK29 Mixed Gas Rebreather, to conserve helium, accelerate deployment of Navy divers and increase safety.

Navy diving missions include underwater rescues, explosive ordnance disposal, ship hull maintenance, recovery of sunken equipment and salvage of vessels and aircraft. Navy divers breathe a careful mixture of oxygen and nitrogen. Below 150 feet, however, nitrogen becomes toxic-leading to nitrogen narcosis, a drowsy state that can dull mental sharpness severely and jeopardize safe return to the surface.

The solution is to replace nitrogen with helium. However, helium is expensive and hard to obtain because of recent worldwide shortages. And the Navy needs a lot of it for missions and training exercises, requiring canisters of the gas to be transported on accompanying ships or planes.

The MK29 rebreather decreases helium requirements by approximately 80 percent. Used oxygen-helium is filtered through a carbon dioxide scrubber which removes carbon dioxide and recycles the breathable gasses back to the diver. This results in very little venting (giveaway bubbles) and very little wasted helium.

Test results suggest this system will be a major asset to Navy divers who can not only perform more dives but also stay underwater longer if surface supply gas is interrupted. The MK29 reduces breathing noise and fogging of helmet viewports. It’s also the first piece of Navy diving equipment to feature 3D-printed titanium tubing that connects hoses from the helmet’s breathing manifold to the regulator backpack. That titanium reduces the risk of breathing hoses being sliced by sharp or jagged underwater objects.

The system was developed by Naval Surface Warfare Center Panama City. The technology is sponsored by the Office of Naval Research Global (ONR Global) TechSolutions program. TechSolutions is ONR Global’s rapid-response science and technology program that develops prototype technologies to address problems voiced by Sailors and Marines, usually within 12 months.

The rebreather is hoped to be issued throughout the fleet by next year.