It’s curtains for those under the sea

The US Naval Sea Systems Command (NAVSEA) recently finalised an $850,000 order to outfit the US submarine fleet with innovative lithium hydroxide curtains.

Developed and produced by Battelle, the lithium hydroxide curtains remove hazardous carbon dioxide that can accumulate in the atmosphere of a disabled submarine, improving the crewmembers’ ability to survive while awaiting rescue.

First used by submarine sailors prior to World War II, lithium hydroxide crystals react with and absorb carbon dioxide that builds up in an enclosed environment. Stored in canisters on board all submarines, the crystals are used in hopper fans if power is available or spread out on bunks or the deck in the event of an emergency or power failure. Due to a caustic dust produced by spreading the lithium hydroxide crystals, however, this last method is only employed as a last resort.

The new design uses a polypropylene-fabric that contains the lithium hydroxide crystals. Resembling an air mattress, a curtain is made of five sealed channels that enable passive absorption of carbon dioxide while preventing lithium hydroxide dust from escaping and irritating the submariners’ lungs and skin.

Unlike previous methods of dispersing the substance, each 7.5-foot long curtain is lightweight, easily stored in the limited space of a submarine, and most importantly requires no electrical power to operate. In addition, the solution is inexpensive – curtains cost just $19 each.

There is also another surprising advantage to the curtain. With temperatures at the bottom of the world’s oceans hovering just above freezing, hypothermia can be a serious threat to sailors in a disabled submarine. The heat produced by the chemical reaction of lithium hydroxide crystals absorbing carbon dioxide, can rise upwards of 140 degrees Fahrenheit, and be harnessed by the curtain. By lacing several curtains together using grommets along the edges of the fabric, sailors can create an enclosure which can provide a heat source.

By late 2004, every submarine in the US fleet is expected to be outfitted with the new curtains.

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