This system keeps the volume of mixed gas to an absolute minimum and therefore reduces the magnitude of a backfire. Injector-mix systems have far larger volumes of mixed gases in the torch and nozzle. Should a backfire occur, far more extensive damage to equipment, or operators, can result.
Nozzles are made of copper for good heat dissipation. Nozzle faces can be dressed back by using a fine file and orifices cleaned with appropriate cleaners. The flame shape and nozzle performance depend heavily on orifices having sharp, square edges – they should never be bell-mouthed by using pieces of wire to clean them out – use only approved nozzle cleaners.