The Flux Flow Control, integrated on all M-series nitrogen machines of Vitronics Soltec, prevents flux contaminants from ever reaching a reflow oven’s cooling zone, where they can condense and cause product contamination as well as corrosive build-up on parts. It does this without filters or condensers, effectively reducing system maintenance. This patent puts an end to messy fil-ters, tough cleaning problems and their associated scheduled downtime and lost production. The key is an individual zone exhaust principle: inerting gas is recirculated in a manner which inhibits flow into the cool zones, concentratingcontaminants for exhausting through the normal ducting without the need for in-process filtration. An oven maintains a pure inert chamber without accelerating gas usage. A positive inert gas pressure keeps contaminants out of the cooling module where they can condense and cause problems. The result is clean inert processing, with no flux-encrusted condensing modules or filters. Boards and assemblies remain free of contaminants. Reflow soldering systems, which are operating in an air mode, exhaust flux fumes quickly via the individual zone exhaust and in high enough volumes to prevent condensation within the oven. Field tests have shown that dismantling and cleaning is up to eight times less frequent than with other ovens.