Old 07-27-22, 05:53 PM
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bulgie 
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Originally Posted by MassiveD
Here are 3 rules for acetylene use, And there are a lot more than three rules...

https://www.youtube.com/watch?v=lEVBoc4tLoI
That vid is out of date; it gives the acetylene withdrawal rate as 1/7th of tank capacity per hour. But the welding powers-that-be have since decided that's too generous, and even at 1/7th you can get into trouble, so they lowered it to 1/10th.

I don't know how bad it is to withdraw at 1/7th, which used to be considered safe — for decades, I think. So maybe 1/10th is too conservative? All I know is, I have exceeded the max (don't know at what withdrawal rate) and gotten liquid acetone coming through the line. It can rapidly degrade the hose and regulator, causing a leak or explosion later. If you have had acetone come out the torch, best to replace the hose and overhaul the regulator with a new diaphragm ASAP.

So now when I have a big heating job that needs a quite large tip such as a rosebud, I use Propane/LP — with oxy of course. Unforunately propane needs considerably more O2 than acetylene, so the biggest flame is probably beyond what a 5 lpm concentrator can do. Doug Fattic reports running a rosebud on one, but in my experience the flame was not as big as what I can get on bottled O2. Maybe a 10 lpm concentraor would convince me to ditch my O2 bottles? Dunno, I keep looking for one cheap enough for me, but I'm really cheap. 5 lpm is enough for anything short of the biggest heating jobs though.

People reading this forum tend to be amateurs or small-scale pros who tend to have smaller acetylene bottles. If you absolutely need to run a big rosebud on O/A, without enormous Acetylene bottles, the only other solution is a manifold that pulls from several bottles at once. I don't know anyone that does that in the bike biz, though I hear it is done sometimes (or used to be done?) in industry.

Mark B
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