Uniweld NV1 NitroVue Nitrogen Flow Indicator Easy to read flow indicator label and the precision adjustable valve give complete control over the low flow of nitrogen gas Bright orange float ball visually confirms the flow of nitrogen gas Purge the copper lines at 20+ SCFH and then reduce the flow to Braze at 3-5 SCFH during the brazing process Protected from over pressure with a reseatable safety blow off that opens at 200 psi