* New and boosted version is the Uniweld NV1 Nitrogen Circulation Indicator * Uniweld UNF3 Nitrogen Circulation Indicator offers very reduced pressure precision gas flow control for nitrogen purging applications throughout the brazing of copper tubes in A/c and Refrigeration systems. The nitrogen must be streaming to displace the oxygen inside the tubes throughout the brazing process, stopping internal oxidation and the resulting scale. Range develop inside the tubes could trigger clog in the TXV and within the A/c and Refrigeration system resulting in premature failing. The UNF3 Nitrogen Circulation Indicator uses a float sphere to aesthetically validate the nitrogen is streaming and permits the professional to very first flush the copper lines at 25-35 CFH and then lower the flow to 3-4 CFH throughout the brazing process hence conserving and saving nitrogen. If the sphere does not rise in television there is no flow of nitrogen only fixed pressure and oxygen is not being displaced. The UNF3 maximum inlet pressure is 50 PSI and must be linked to a Nitrogen Regulatory authority with 1/4 inch male flare outlet link (Uniweld Component No. RHP400, RHP500, RHP800 - Sold Separately) to control the nitrogen gas pressure.