There was a study just released. It looked at oxygen flows from cylinders and concentrators at 1 lpm, 3 lpm and 5 lpm over various lengths.
Before I spill the beans on the results, I would like to hear what others are using, think is safe, or have been told by your home care providers on the length of tubing that you can safely use with your oxygen equipment.
I will post results later today. Have fun with this one!