Last year I used welders o2.  I still have a near full tank.  I have 2 of the biggies which are pain to take with me when I go out.  My question
What differest size tanks do you have?  And how many of each should I be asking for?

thanks

An E tank holds about 685 Liters of O2.

At 15 LPM, you get around 45 minutes total
At 25 LPM, you get about 27 minutes total

Multiple E tanks are a must.

I use welders O2 but I bought a "transfill" hose kit to let me fill my own E tanks and a tiny M9 tank that provides enough for one hit. It's a great little tank about 12" long and has a carrying case that looks like a video cam bag, but holds the tank, regulator and mask. (Thanks Phil!) The little tank only holds 250 liters.

Marc