When brazing copper, it is imperative to purge with nitrogen in order to minimize or eliminate oxidation that results from heating the copper pipe. Without purging, oxidation will occur and the oxidized flakes that result can and will break off and flow through the system, damaging bearings and fouling system filters. All that is needed is a low pressure, low volume flow of nitrogen. The use of dry nitrogen gas also minimizes the need to evacuate moisture from the system.