If your oxy-acetylene torch rig is "popping and sputtering" here's a few thoughts- from my 45 years in the welding trade- First off- make sure the tips are clean and clear- Oxy-acetylene produces a 6000 F temperature with a "balanced" or neutral flame-If you just use acetylene alone, all it will do is smudge- and today, with the explosion at the Union-Carbide plant in TX a while back, acetylene is rationed and very expensive- Mapp gas with oxygen gives about 5600 F at a neutral flame, and commercial propane about 5200 F- propane is mainly used for scrap yard rough metal cutting, and also for heating die bases etc prior to welding--
You cannot interchange fuel gases- without changing both the valves in your torch set, the tips, and also the regulator- I two-stage regulator is always the best buy- both for fuel gas and also oxygen- more expensive, but the cheaper single stage regulators will drop off delivery pressure as the volume in the tank decreases- dual stage regulators will maintain the delivery pressure no matter the volume in the tank(s)--
Trouble-shoot your hoses and connections- use soap water or "Bubble-leak-Check" on all fittings, if you have older hoses with kinks or bends, check- with the delivery value open (you don't need to light the torch here) check under delivery pressure for leaks- if you have them, R&R (remove and replace)-
In regular oxy-acetylene cutting of mild and fab steels, too many 'rookies" use way too high a pressure setting on both acetylene and oxygen- without changing the tip size- thinner gauge metal- smaller tip and orfice openings, lower op. pressures- also- you might see the "red-line" on your acetylene regulator delivery gauge- at over 10-15 range (usual red line markings) acetylene becomes unstable- and if you have multi=-head heating torches, that might be the cause of your problem. Also be careful with delivery and handling of your acetylene tanks- that must be transported and store in the cart UPRIGHT- if you tip an acetylene tank on its side, you should re-stand it upright and wait at least 5 hours for the calcium carbide gas to work from the inert (Fuller's earth or clay compound) that holds it in a somewhat stable condition in the tank-
Solder has a critical temperature of about 500 degrees F--one reason why the Hardware store Turner propane hand held torches will work for "sweating" copper pipe joints--I would like to see photos of this dual torch heating rig of yours before I can comment further- RWTF
