Gas pressures and flow rates

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I've been trying to correlate my torch usage to my acetylene consumption, and have come to a conclusion. I'ld like to hear your opinions on this. My conclusion is that if you adjust the acetylene to where the soot stops, for a given tip size the flow will be the same no matter where the regulator pressure is set. The Victor charts have consumption rates all over the place. There are two entries for the "0" cutting tip that shows a consumption rate of either 6-11 or 9-16 SCFM, depending on whether you're cutting 3/8" or 1/2" steel. It doesn't make sense to me. I did maybe 4 hours solid of cutting, going back an forth between a 2 and a 0 tip, and I pretty much emptied a 140 cu ft tank. When I say empty, I mean the high side gauge is dropping to zero, and only creeps back up to 20 after a while. That seems way too high of a consumption rate. I'm using a 150 cu ft oxygen cylinder, and took that down from full to about 800psi. Any thoughts?Last edited by Moparfever; 03-14-2011 at 09:25 AM.
Reply:The flow rates differ so little between tip sizes that close (I've also spent days cutting using those tip sizes) that it doesn't matter much.I ignore flow ratings on small cutting torch tips but DO watch the gauges when using small acetylene tanks.  The propane jug comes out if in doubt. There is no reason to do "questionable" withdrawal rates with acetylene. Slap that regulator onto a propane jug, switch tips, go cut. Scrappers use propane for good reason.I set acetylene at about 8psi  and oxygen at about 30-40.  Same with propane, or maybe a few psi more for ordinary cutting.Your consumption rate sounds reasonable when cutting constantly. When I say empty, I mean the high side gauge is dropping to zero, and only creeps back up to 20 after a while.
Reply:4 hours of cutting with a #2 tip should totally empty a 140CF acetylene tank.  Make sure you do not have any leaks.  Also, check the accual cuft of your acetylene cylinder.The supplier will usually have a white or silver making with the accual cuft in that cylinder.  Because of the filling method, you can not always get 140cuft in the cylinder.Many supplier will charge you 140 cuft even when the cylinder has less in it.Hope that helps.OAdoctorwww.regulatortorchrepair.com
Reply:"4 hours of cutting with a #2 tip should totally empty a 140CF acetylene tank." Okay, my Victor chart says a #2 uses 18SCFH of acetylene max. That would equate to 7.8 hours if you could use all 140 cu ft. Is there some "rule of thumb" I don't know about? I was setting my flame a little on the low side to conserve as well. A tiny bit of soot, but quite a bit lower than where the flame starts to jump off the tip. By the way, I picked up a propane bottle. I'm hearing a lot of positives on this site about propane for cutting.
Reply:Originally Posted by Moparfever"4 hours of cutting with a #2 tip should totally empty a 140CF acetylene tank." Okay, my Victor chart says a #2 uses 18SCFH of acetylene max. That would equate to 7.8 hours if you could use all 140 cu ft. Is there some "rule of thumb" I don't know about?