Given that an acetylene refill is now $45 (around Indianapolis) and based on Doug Fattic's excellent post on propane, I decided to switch. I even went so far as to pick up a used oxygen concentrator. I noticed that when the torch isn't connect to the oxy con, the flow rate can be maxed at 10 LPM (invacare platinum 10), but as soon as I hook up my torch, the flow rate drops to 4 LPM. I'm using a Meco Midget torch with a #5 fuel tip (which is bigger than the aw207 Fattic recommends). It seems like the problem is the internal restrictions of the torch body, not the tip or the line. I tried increasing the pressure of the oxy con output, but it had no effect. I don't seem to be able to get enough O2 out to really take advantage of the #5 tip. Do folks who use the uniweld or smith torches see a drop in flow rate? Do you feel like you get plenty of oopmh from your oxy concentrators?