@ 10-15 LPM, an M tank will last about 3-4 hours at constant flow. I don't even mess with E tanks anymore, they are gone in about 20 minutes at a 15 LPM flow. I now use welding service K tanks for the price to refill is minimal to medical O2 prices. I am on medicare and they don't cover O2 for CH, I really wish they would but they don't unfortunately. No chart will make you feel at ease like a stack of tanks there ready when you need them, that's why I have gone to the big welding K tanks.

This is of coarse dependent on the regulator flow rate. large O2 tanks hold 2,200 PSI while small E tanks are only 1,200-1,800 PSI when full. You can easily get the parts to make a non rebreather setup for under $5 at the local disability supply store and use off the grocery store shelf gallon size zip lock bags for the accumulation collection reservoir. Then use an asthma nebulator style mouth tube (with air mix inlet slot covered over by electrical tape) instead of the cumbersome face mask setup, this works the best for me to get the O2 into my lungs in a super expedient manor without respiration effort from a mask type apparatus. There is no way I can use a mask when my CH affected side eye and nostril are draining snot and tears, and a mask setup makes me feel like I'm being smothered (hard to breath easily).

The O2 therapy is completely useless if you can't get it to work for you, there is a learning curve associated with using O2 properly. I believe this is why many CH sufferers don't get the proper O2 relief and give up on it, because they aren't getting the O2 deep into their lungs in a purposeful manor, and thus they give up on the best thing there is for aborting the horrid KIP 8-10 level pain that makes us bewildered CH sufferers want to kill ourselves. I am 100% in saying that 15 LPM O2 has literally saved my life, without it I would have put a bullet in my head many years ago.

The medical suppliers only have 8 LPM regulators, you will have to purchase your own high flow regulator to make the O2 therapy work, or get a welding style regulator that can supply the needed LPM flow. I usually go for 15-20 LPM, a pitiful 8 LPM tank regulator is not going to work for CH relief.