KITTED-UP
1 . The Aqua-lung
In 1943 , Cousteau and his engineer pal Emile Gagnan worked out a simple system to supply air from a high pressure cylinder worn on the diver ’ s back only when the diver needed it – on ‘ demand ’. As the air was not being continually supplied , it used much less . The reduction in pressure was done in a single step , from the cylinder to the diver – as the diver breathed in , levers pushed against a valve and the cylinder tipped air into the breathing hoses . The upside was freedom from the annoying tether of a hose ,
so the diver could swim about and explore . The downside was the limited capacity of the cylinder , and the twin-hose demand valve was sensitive to where the diver ’ s head was in relation to the cylinder valve making for either hamster cheeks , or having to suck the air in like a thick shake .
Inventors of the demand valve , Jacques Cousteau and Emile Gagnan
2 . The single hose regulator
One for the Aussies here , in the early 1950s . The reduction in pressure is done in two stages – the first stage drops the pressure from the cylinder to about 10 bar , the second stage to the ambient pressure . As it ’ s done in two steps , the regulator is easier to breathe from , is less sensitive to head position , and the hose only needs to connect the two stages together , so you don ’ t have the annoying loop of corrugated hose getting in the way . The design hasn ’ t really changed since the invention – sure , there have been incremental improvements ... but the principle is the same .
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