Abstract: An automatic system and method for changing a disposable nozzle for a multiple component reactant mixture injector. A robot supports a mixing head that is used to inject a reactant mixture. The robot moves the mixing head including a shroud and the disposable nozzle to a nozzle changing station. The shroud is retained on the mixing head by a threaded collar that is unscrewed at the nozzle changing station by a nut runner. The used nozzle is ejected from the shroud, engaged by a gripper and disposed of while a new disposable nozzle is obtained from a magazine and placed in the shroud. The threaded collar reattaches the shroud to the mixing head and the mixing head is returned to operation.