This is an e-tank.
It is the most commonly used size of tank and is probably the one you think of when you picture someone on oxygen. You probably also picture the little dolly, too. The tank is 25" high and 4.38" diameter, holding 625L of oxygen when full, at a pressure of 1900 psi. There are smaller sizes (down to A tanks) and larger tanks. I have an H tank in my hallway. It is the size of a six-year-old. (Thanks to openanesthesia.org for the tank info.)
In my backpack, I carry D and C tanks (ML9 and ML6 actually, but close enough). They don't hold as much, of course, but with a conserving device, that's not generally a problem. And I can refill mine. Not so with E tanks. And let me stress: D tanks and smaller are SO much more portable. Infinitely more portable!
I make this point because I've been on oxygen for almost a year now, but it wasn't until this recent trip that I've been saddled with e-tanks. For five days I juggled 14 of them.
Now, I've gotten used to dealing with being tethered to a tank or concentrator. I've gotten used to paging my oxygen hoses as I walk around the house or office. But I have NEVER felt as handicapped as when I was wheeling e-tanks behind me. It is a whole new level of onerousness. I had always protested against the handicapped label to this point. How handicapped can I be if I can shoulder an oxygen tank and walk most any distance I want to, however slowly I may have to? But with an e-tank in tow, I started to look for closer parking spots and kinda wishing I had that handicapped parking tag.
Can't give in to that kind of thinking. I CAN walk and so I should. But man am I glad the e-tanks are gone and I'm back on my Homefill D tanks again. My supposed handicap is respiratory failure. But the very thing supposed to relieve that handicap often is what actually makes me feel handicapped. And for the most part, I didn't feel that way at all until my only portable oxygen was e-tanks in a cart. Now THOSE will handicap a person, respiratory insufficiency or no.
I'll leave my anger issues at not being able to use a POC or a Helios system for another post.