Victor 6-MFA-1 rosebud pops out after 5 minutes - I'm stumped

Nearly new tip, no trouble with welding tips. Handle valves are fine.
Using 10 psi acetylene and 12 psi oxygen, both tanks over half full
Good seating surface, no hose leaks.
No trouble starting and adjusting flame, but after several minutes it
suddenly backfires once, then a second later it pops off completely.
Tried different pressures but lower acetylene pressures seems to make it
worse. Why does it work fine for several minutes and then suddenly backfire
without touching anything????
It's consistently doing this, help, I'm stumped.
Reply to
bw
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It sounds like you may be starving the rosebud. Read the Victor manual to see the volume of acetylene needed for tip to operate correctly. If you are using a small acety tank you will have starving problems. I hope this helps
Reply to
MES
Are you using 1/4" or 3/8" hose?
1/4" hose is too small for a large Victor rosebud tip. It starves the torch for gas.
This a common problem
Reply to
Ernie Leimkuhler
Additionally one cannot draw more than 1/7th (one seventh) the volume of acetylene per hour from a cylinder. If you were to try to do so, you might suck out some of the acetone in which the acetylene is dissolved.
j
Reply to
John Gullotti
Yes. Took a night class 5 years ago, excellent teacher. I do mostly repair work, but not every day. The aceylene tank is 28 inches high x 7 inches diameter, maybe size W, about 6 years old, has 1000 PSI right now. The Victor handle is model WH26FC, with regulators everything in a package, but lost the documentation. The rosebud is 9/16 inch diameter, with hex spaced holes (6), each one about 1/16 inch diameter. I had thought it was a "#1" rosebud, but it is clearly marked 6-MFA-1 on the collar. I always considered this to be light duty, mostly fixing sheet metal, brazing, garage work. Inspected the hose lines, look new, external diameter of each is line is at least 3/8 inch.
Will ask local instructor next time I'm in town, he has 40 years in the oil fields, has every certification ever printed. Maybe I am pulling the acetone, but the tank is never disturbed.
Thanks guys.
Reply to
bw
It sure sounds like you are starving the rosebud tip, your cylinder sounds like a 110 cf capacity and if I recall correctly the rosebud you are using requires approx 40 cfh which is alot more than the 1/7 of cyl capacity per hr.
Reply to
MES
3/8" hose is 3/8" on the inside. If your hose is 3/8" on the outside then it is 3/16" hose.
Way too small for almost any rosebud tip.
Reply to
Ernie Leimkuhler
Yes, I was concerned about that, but I measured it last night in the dark, today I see it's almost 1/2 OD so it must be 1/4 inch ID hose, anyway it all came with the Victor kit. Measured the rosebud hole openings, actually 0.040 inches. Also, the acetyl tank pressure I read was really 100 psi, the O2 tank is 2000. Spent some time cleaning everything. That tip had been in a dusty storage environment, and I needed to clean it better due to my earlier backfiring-sooty ignorance.
Now the thing seems to be working just fine. Holds a neutral flame over 10 minutes and I got the job done. I was probably pushing it close to the limits, got in a hurry. That's not smart behavior. Sometimes I just like to get rid of some customers. Will be back to brazing with the #1 tip. thanks again
Reply to
bw
I just got a Victor setup new in the box - 1/4" hose set - Medium size Acel/Ox set. I got the propane head and a tip for it and now have it on my Propane/ox tank. Brazing with it. Works just fine.
Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder
bw wrote:
Reply to
Martin H. Eastburn
I use a victor 8MFA, which I think is bigger than the 6MFA. I went to pretty big tanks, the OXY tank of the set is five feet tall. I had to buy new regulators to pass enough gas. After all that, I can run it at 10 psi of acetelyne and 14 psi of oxygen and have little trouble. It still pops off if I don't have it turned up high enough.
I got all this so that I could sand-bend exhaust headers for vintage race cars. Works a treat. I just finished sand-bending a new roll-bar for my Formula Ford using .120 wall DOM mild steel tube, 1 3/8" OD. To make it look right and fit right I needed the bend to start gradual, go to quite a tight radius of about 4" then open out gradually again, with a gently re-curve on both sides. Total bend of about 150 degrees at a guess. You could do it with a mandrel bender, but it would, have looked right.
Brian
Reply to
Brian

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