Problem with air/acetylene prestolite torch tips

I'm an air conditioning/refrigeration tech and have been for 37 years.  So I've been soldering copper tubing for as many years.  Recently my torch tips have been spewing out yellow flame with black soot instead of the nice blue flame needed to accomplish my work.  I thought I had bad gas, so I got another tank of acetylene...same thing.  I then thought Ok, Iv'e got dirty tips, so I tried blowing them out with 150lb. of compressed air, then co2, installed new filter screens in the base of my no avail.  I then purchased a new uniweld kit.  it came with one new tip.  It works with the new tip but not with my older tips.  And I need to use my older tips as 3 of them are double tips which allow me to heat the larger tubing quickly from both flames across from each other.  I don't know what to do at this point.  I've talked to several welding supply shops and no one has as answer.  HELP!!

Rich Waugh's picture

Your problem sounds as

Your problem sounds as though your tips are drawing more gas than a small bottle can supply, so they are pulling acetylene from the tank. That is bad, for sure. Have you tried them on a larger bottle? You might want to take them to the welding supplier and try them once on a larger cylinder to see if this is the case.