Humans are air-breathing animals and so working underwater requires special equipment to help them breath and to deal with the water pressure. One of the displays in the Naval Undersea Museum in Keyport, Washington focuses on NEDU—Navy Experimental Diving Unit.
One of the challenges facing divers is that breathing compressed air below depths of 165 feet can cause nitrogen narcosis which impairs the diver’s judgement and awareness and thus endangers both the diver and the diving operation. The solution to this challenge emerged in the 1930s when NEDU developed and perfected a new breathing gas mixture using helium. According to the Museum:
“Breathing helium-oxygen made deep-sea diving safer and let divers dive deeper. Today using helium is standard Navy practice for surface-supplied dives to 190 feet or greater.”
According to the Museum:
“The distinctive banana-shaped assembly chemically absorbs exhaled carbon dioxide, allowing the helium to be reused.”
According to the Museum:
“An atmospheric diving suit maintains surface pressure internally, which protects the diver inside from deep-ocean pressure and eliminates the need for decompression. A diver operating NOMOADS could work as deep as 2,000 feet for 40 hours. Today the Navy uses modern atmospheric diving suits for salvage operations and ocean exploration.”
According to the Museum:
“Post World War II, NEDU faced the challenge of keeping divers warm. Staff repurposed an aviator’s neoprene exposure suit, which had its tester perspiring 1.5 hours into a cold dive. Through additional experimentation, NEDU tsted neoprene thickness and overall design to maximize thermal and physical protection.”
According to the Museum:
“Thermal protection is especially critical at greater depths (water becomes cold with depth), when breathing helium (which draws warmth from the diver’s body), or during saturation dives (which last several hours at deep depths). Hot water suits manually bathe divers in hot water from the surface, keeping them toasty warm.”
More museum exhibits
Naval Undersea Museum: Diversity and change in U.S. Navy submarines (museum tour)
Naval Destroyer Museum: On the deck of the Turner Joy (photo diary)
Lewis Army Museum: Half-Tracks (photo diary)
Lake Chelan Historical Society: Homestead Cabin (photo diary)
Campbell House: The kitchen (photo diary)
Museums 101: Interactive Robots (Photo Diary)
Museums 101: Under the Arctic (Photo Diary)
Carillon Historical Park: Transportation Center (photo diary)