A system and method for protecting a nozzle that injects a high velocity main gas into a furnace or combustion zone. The nozzle is located in a passage recessed from the exit port opening of the passage which communicates with the combustion zone. Purge gas is passed into the passage upstream of the nozzle. The volume of the purge gas exceeds 50% of the total volume of the main gas and purge gas and the purge gas has a velocity of at least 100 ft/sec thereby preventing furnace gases from entering the passage and attacking the nozzle.