Quote: (Originally Posted by
Data)
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
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.)