BarryNL(Offline)

What would be the best choice for a stage bottle with tech1 in mind (aluminium, obviously). I can't see any particular requirements on the GUE site for tech1 and even tech2 only requires bottles of 30cu.ft or greater. Is there any reason to get a bottle larger than 40cu.ft.? Are there any other requirements I need to know other than material?

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Jussi(Offline)

Hi Barry! (and thanks again for DIR-F course!!)

Was just talking here with my Tech1/Cave1 trained buddy and he said to get 80cuft tank,
that's what they used on their T1 course. He has 21M MOD stickers on it.

Other requirements. Dive, dive, dive, have fun, have fun, have fun.Train, train, train and ascents/decents need to be top notch ;-)

MonkSeal(Offline)

It's a deco bottle rather then stage, to be precise I guess that AL40 is usually used in US; in Europe AL 7 lit is common. However, you can use AL80 as well. Recently, I had the opportunity to dive AL 10 lit and it's also Ok.

BarryNL(Offline)

I have no problems with ascents. It's not on video, you can't prove a thing.

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David Martin(Offline)

Get a 7L or CE marked AL80. For most T1 dives a 7L will be fine. For dives at the max T1 depths you may find that the limiting factor with a D12s+7L would be the deco gas, at which point you'll get a slightly longer dive with an AL80.

Chosing a 7L is a little more complicated than the 80. You either want the "old style" ie pre-approx 2002 or a new 207 bar rated one (which is the same as the old pre-2002 7L but with is stamped with a lower working pressure). The most commonly available 7s are "new" 232 bar cylinders which have thicker walls than the other two and are from memory a bit more than 1/2kg heavier as well as a little longer (due to the reduced internal diameter).

And get a silver one because they look best

David

LauNar (Online)

Except when they get blown out by strobes in photos.

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//LN
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My UW photos

BarryNL(Offline)

Thanks David. Out of interest, how does GUE calculate deco gas requirements for the T1 dives? I notice DecoPlanner spits out something in the range of 930 litres of EAN50 needed after 25mins at 45m with 21/35. Of course, this would assume you don't feel like giving your buddy any gas, or indeed having any spare yourself.

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Data(Offline)

Just as we calculate any gas requirement.
SAC rate X ATA X time
e.g.
let's say you have 25 min deco from 70' to surface.
let's say your SAC rate is .5
average ATA would be 2
2X .5 X 25 = 25cf of gas needed

Fredrik Taule(Offline)

Add 50% to that calculation for safety/backup (self&team) and you're good to go.

(Like with most other things, thinking also apply here. Strong currents and so on, potential for higher consumption rate, more conservative gas planning, the usual.)

And to the original question;
7l 200bar (weighing 8,9-9,0kg's) Luxfer aluminium cylinders are the preferred cylder size for the '21' gas here in Norway, unless you want to go for a 80cf cylinder which are also available with CE approval as mentioned earlier in this thread.

Best,
Fredrik

(PS! I belive that Luxfer UK only gave it one 'not all that successfull from a manufacting and cost point of view' shoot with the unpainted 7l 200bar cylinders and will probably not do it again anytime soon.)

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Oceanic Tech, Fue.no - www.fue.no