Dress For Success...

[rjack321]

Would you seriously consider adding 3000psi of oxygen to an aluminum tank on the supposition that it was "oxygen cleaned" from the factory? If so, you're a braver man than I.

They come o2 clean or not, same price. Luxfer makes oygen cylinders of all types, assuming the plug's still in it and its got the Luxfer O2 sticker on it, its still clean.

 

[rjack321]

If you end up in 4 years, with sufficient funds to move toward tec, you may well find that you dive with an 80 AND a 40 as deco bottles, sometimes one, sometimes the other, sometimes both. If you deco on back gas, you face some possibly long hangs, and that is not ideal, even if it is a usual contingency. If you dive a single deco mix (let's say 50% O2) depending on how deep you went, how long your bottom time was, etc, and therefore what your deco schedule calculated out to be, you might find you needed more gas than a 40 would provide, so you might dive an 80. You might find an 80 was fine for one mix decos, but you wanted a shorter deco time, so you would want a second bottle, probably a 40, with 100% for the 20' stop. Certainly, part of tec training would include managing a single gas (back gas), managing two gases (back gas and a deco mix) and managing three gases (back gas, and two deco mixes). Some (smaller, low SAC rate) people will dive two AL40s. Some more enthusiastic breathers (like me) dive a 40 and an 80. Some even dive two 80s.

DIR does not use 2 deco gases at the entry tech level (Tech1). By custom most people in the US are using an AL40 for 50%. Some long shallow Tech1 dives would use 100%. Anything below 130 would definately use just 50% to keep the rock bottom reasonable. If an AL40 is not enough gas because of a high consumption you would limit your exposure in lieu of bringing a bigger cylinder. Why? Because if your consumption is too high for a AL40 and you need a AL80 (60cf need), you won't have enough backgas to bailout onto should you lose the AL80.

If this one deco gas is insufficient, you are doing a Tech2 dive and 100% would be used in addition.

1) therefore roughly 30 mins deco is a Tech1 limit because you don't have enough backgas to bailout for longer commitments (hence the O2)
2) 80% is never used by GUE/DIR
3) Even Tech2 divers typically use two AL40s

Not trying to bust your chops Colliam7, but most of your comments weren't DIR, and since this was asked in the DIR forum - I assume that's what the OP was looking for.

 

[mwhities]

Thanks all.

My question was answered and I do appreciate everyone's comments and suggestions. Alll all noted.

Michael