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<font color='#000F22'>anybody know about heliair,what deco tables to use ?.
 

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Heliar's no different from trimix in terms of deco planning - it all boils down to how much He you've got in the tins. The real complication on OC is the fact that a strong heliair is likely to be hypoxic, so you need to be thinking in terms of a travel gas.  That said, a 10/52 (half Helium, half air) will be life-supporting after 6m so you have a fair amount of flexibility in terms of deco/travel gases.  You do get a bit of a battering on stops using Buhlman-based tables when you're on a strong mix though, mainly cos Buhlmann never really got the chance to properly investigate He's properties.
 There is much debate currently about the pros/cons of Helium in terms of deco obligation - there is a large contingent in the gas-diving community that holds the opinion that because He off-gasses so cleanly (being so light) you can dive some very aggressive profiles with no ill effects. I've seen divers treat 16/40 mixes as an air dive, just using slow ascents and deep stops.  Whether you do this or not is a judgement call - - just remember if you get a Helium bend you won't just start off with a sore elbow - you'll drop like a sack of spuds.
Depends on what sorts of depths you're planning for really - let me know & I'll point you in the direction of some good software.  Might even have some stashed on this PC.  You ain't seen me, right?
 

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[b said:
Quote[/b] (Rob Evans @ June 07 2003,00:11)]just remember if you get a Helium bend you won't just start off with a sore elbow - you'll drop like a sack of spuds.
Depends on what sorts of depths you're planning for really
Rob - this interests me. Have you got any web references I can look at with regards to this (chemistry wasn't my strong point as a kid but I'm not a numptie with this stuff now)
 

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Alas no - just anecdotal stuff from a couple of mix instructors I know who've seen it happen a few times.  Not pleasant apparently, but thankfully the parties concerned all survived due to prompt radio work & helicopter trips.
 

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<font color='#000F22'>cheers
         rumour has it there is an interesting dive in one of the lakes at 70m. thought i might have a go at it coz i dont know anyone who has done it
 

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On the subject of trimix, can a mix with say 36% O2 and an appropraite %age of helium be treated the same as EANx36 with regard to no stop limits on nitrox tables.  I would be interested in using it just to keep off the narcs.
 

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You can - but as 36% is only good for a max of 34m @ 1.6PO2 (not good practise) and 29m @1.4 PO2 do you really get narked enough at that depth to warrant the cost of training/gas?
Not in any way a criticism BTW - I'd only really consider He in the mix for 40+m dives nowadays; decided to make the change to Trimix when I started pushing 50m on air & was totally failing to enjoy/remember the dives.

Getting back to the point though, generally speaking having a He content of say 21% would have no real effect of your deco/no stop times in terms of planning and will take the edge off the narcosis.  Again, a nice slow controlled ascent with a Pyle stop or two thrown in will get you out of the water nice & safe.
Then again, I'd recommend Pyle (or Gradient Factor) stops on any dive.  You get out of the water feeling much perkier.
 

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[b said:
Quote[/b] (karl_winrow @ June 17 2003,21:39)]On the subject of trimix, can a mix with say 36% O2 and an appropraite %age of helium be treated the same as EANx36 with regard to no stop limits on nitrox tables.  I would be interested in using it just to keep off the narcs.
<font color='#000F22'>Basicly run the rpofile on the computer with 20% He and without and compare the diferance.

36% Max 29m so forget that If your that narked at 29m your in trouble. Start off looking at 28% for 40m

28% o2 dive for 40min to 40m deco time 58min
28%o2 20%He For 40min deco time 58min

Hey thats exactly the same according to deco planner


Always check first but I basicly run my Vitec in Nitrox mode untill I put more than 20% He in the mix and do standard deco. If I drop below 55m its more He so back on to tables we go.

I will usualy put 20% in between 40 and 50m
30% up to 60m and 40% to 70m.

Did a 60m the other day on 18 /40  36% and 80%. Gas fills for twin 12 back gas a 7ltr of 36% and a top off of 100bar in my 7 ltr of 80% came to £50.00 and thats cheep.

HE is lovley stuff but damed expensive. £1.00 per 1 percent is a good guide.

ATB

Mark Chase
 

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He expensive? Never costs me more than £6 a fill of 10/50, and that's good for 2 loooong gas dives.  Then get an air top for nothing so I'm on something like 12/42.  2 more looooong dives.
Off to get me a J of He today.  Should last me a couple of years.
 

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<font color='#000F22'>The English dictionary failes miserably to come up with words to discribe the smug grin on a CCR divers face when he picks up his single 3ltr tin of mix for the w/ends diving and the OC boys are paying for four stages and two twin sets.

Two deep gas dives will set me back £80-£100 in gas.


I beleive Rob's version of the smug grin is amongst one of the smugest


I here that there is a new super unit with an experimental bad gas sensor.  Now were cooking. I want one.

Mark Chase
 

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I here that there is a new super unit with an experimental bad gas sensor.  Now were cooking. I want one.


Saw the military version at the Inspiration weekend. Sex on a stick mate, absolutely superb.  A lot of what it had'll be on the Evolution hopefully later on this year.  I want one soooooo badly.

The guys diving the Evo will be very smug indeed.
I'm dead grumpy cos I definitely haven't got the dosh/brownie points for one.
 
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