What is the difference between a backfire and a flashback?
(top) A backfire occurs when the flame momentarily burns back into the torch tip and makes a loud popping sound. Sometimes the flame relights by itself and you can continue working. Other times the flame does not relight and you have to shut off the torch valves. A backfire is normally caused by using the wrong tip pressures, by overheating the torch or by touching the tip to the workpiece. A sustained backfire is more serious. Thats when the flame burns back into the tip and keeps burning inside the tip or the torch at the mixing point. There is usually a high-pitched squealing sound and sometimes sparks coming out of the tip. It is extremely important to shut off the oxygen valve first as quickly as possible, then the fuel gas valve, to prevent damage to the torch. The torch should be allowed to cool and then the set-up should be verified before relighting. Improper working pressures or defective equipment can be the cause of sustained backfire. A flashback occurs when the flame pass
