General Purpose Brazing Alloys

Phosphorus Bearing

The most outstanding feature is their ability to braze copper to copper in air without the use of flux. They may also be used on brass and bronze with the application of Easy-flo flux. Do not use on alloys containing Nickel or Iron.

Product Normal Composition Melting Range ºC Tensile Strength Mpa Optimum Joint Gap Elongation % Colour code EN1044 of 1999 (replaces BS 1845 of 1984); DIN 8513 of 1986 Remarks
Silfos 15 15% Ag:Cu:P 644-800** 630 0.05-0.20 10 Blue CP 102 (CP1);L-Ag15P Gives ductile joints when brazing copper to copper. When torch brazing copper to brasses, flux is required. It finds its greatest use in electrical assemblies such as motor and busbars. Under reducing conditions (e.g. in atmosphere of cracked ammonia) Silfos 15 brazes brass and other copper alloys without flux.
Silfos 5 5% Ag:Cu:P 650-810** 630 0.05-0.20 7 CP104 (CP4);L-Ag5P Provides the best combination of flow and ductility of the group and is more free flowing, yet less ductile than Silfos 15. It is mainly used on refrigeration, air-conditioning and copper-pipe work.
Silbralloy 2% Ag:Cu:P 644-825** 490 0.05-0.20 5 Yellow CP 105 (CP2);L-Ag2P This alloy is more ductile than the copper- flo’s and the inclusion of 2% silver allows for good alloy flow characteristics. It is used where joints are liable to significant stress levels such as hot water cylinders, refrigeration and air-conditioning applications.
Copper-flo 1 7%P:Cu 714-800** 0.75-0.2 Grey CP 202 (CP3);L-CuP7 The copper-flo alloys have relatively long melting ranges and the parent metals being joined almost invariably have high values of thermal conductivity. For these reasons the work should be heated quickly to brazing temperature.
Copper-flo 2 6%P:Sb:Cu 690-800** 0.75-0.2 Pink CP 301 (CP 5)
Copper-flo 3 6% P:Cu 714-890** 0.75-0.2 Orange CP 203 (CP 6)

** A small percentage of higher melting point material remains at this temperature.

Copper-flo alloys should not be used for joints that will be subsequently exposed to heavy sulphurised gases at elevated temperatures.

Copper-flo 1

This alloy is free flowing and economical to use. It is similar in properties and methods of use to the standard phosphorus copper alloy used for joining copper to copper.

Copper-flo 2

This alloy’s outstanding feature is its ability to braze copper in air without the use of flux and its superior flow and better penetration of capillary joints.

Copper-flo 3

This alloy is slightly less free flowing than Copper-flo 1 and is therefore used in applications where an extremely wide plastic range is desirable.