Deco gases

[Mark Chase]

Originally Posted by Simon Ciantar

But I thaught that one should get off Helium as quickly as possible when coming up , I do dives to 60-65mtrs regularly (though usually bottom gas is air so far) and i switch to travel gas at about 30mtrs ( EAN 32- 36%) then to deco at about 15mtrs ( EAN 60- 70 %)

Does the intriduction of Hel in the travel gas reduce eventual deco time ?


Appreciate your comments as this subject has been a question mark for me for some time

If your on air you definitly do not use He in the deco mix. If your on trimix the old school get off the mix ASAP theory is out of date. Now the talk is of reduced Nitorgen gradients and slightly reduced He gradiants in deco with divers runing He in the mix right up to the 6m stop. This alows for cleaner deco but puts much greater emphasis on deep stops and controled ascents. Helium dosent like it if you screw up the deep deco stops and is far more happy on a VPM type deco profile. Nitrogen is slower and is alledged to do more sub clinical dammage but it is a lot more freindly if the asent should be less than perfict.

ATB

Mark Chase

[graham_hk]

I thought (one of) the rationale(s) for He in the deco mix was to keep the PN2 - so you weren't ingasing this problematic inert gas on deco.

I did some 65m dives with 45 min BT on the Prince of wales last year ... would have been a shag if you lost deco gas - so we plan for that. I got sucked in to doing 60min of deco on that dive and got a niggle:-(

Graham

[Mark Powell]

Helium in the Deco mix came up recently. Take a look at this thread

http://www.yorkshire-divers.co.uk/fo...5&page=3&pp=10

Post number 27.