COPPER-FLO filler metals

COPPER-FLOTM filler metals are recommended for the flux-less brazing of copper most commonly for joining tubes and pipes in heating, refrigeration, air-conditioning and heat exchanger components. They have lower ductility than the silver-copper-phos products.



Cu P ISO 17672 Melting Range
92.2 7.8 CuP 182 714 - 810oC


COPPER-FLO is the most free flowing copper-phosphorus filler metal, however, due to its high phosphorus content it is one of the least ductile. It is best suited for making copper joints of the true capillary type and should not be used in applications involving exposure to strong vibrations, impact loads or where some deformation of the joint might be expected in service.



Cu P ISO 17672 Melting Range
92 6 CuP 389 690 - 825oC


COPPER-FLO No.2 is a specialised copper-antimony-phosphorus filler metal. It was specifically designed for flux-less brazing of copper cylinders for domestic and industrial heating systems where it is used for seam joints. The antimony in this filler metal improves its flow characteristics whilst allowing the phosphorus level to be kept low hence optimising ductility.



Cu P ISO 17672 Melting Range
93.8 6.2 CuP 179 714 - 890oC


COPPER-FLO No.3 is a low cost, relatively ductile filler metal (when compared to Copper-flo™), which is not too fluid when molten so can be held in the joint area when brazing. These characteristics make Copper-flo™ No.3 a popular choice for air-conditioning and refrigeration applications. Where greater ductility is required Sil-fos™ 5 should be used.



Cu P Sn ISO 17672 Melting Range
86.2 6.8 7 CuP 386 640 - 680oC


STAN-FOS is not self-fluxing on copper and must be used with a brazing flux such as EASY-FLO Flux Powder. It is free flowing and produces a smooth fillet. STAN-FOS is brittle/not ductile and should therefore not be used in applications involving exposure to strong vibrations or impact loads. It is used primarily on copper to copper alloy joints.


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Jacob Benstead


Mario Porta

Switzerland, Austria and Germany