Copper-flo™ No.3 is a copper-phosphorus brazing filler metal containing a nominal 6.2% phosphorus and
conforming to EN 1044 1999 CP203. It is primarily used for the brazing of copper tubes and pipes in refrigeration
and air-conditioning applications and is a popular choice for this type of work.
When it is used to braze copper the phosphorus within the alloy imparts a metallurgical based self-fluxing
capability. If used to join copper alloys (such as brass, bronze or gun metal) a separate flux will be required
because the self-fluxing action only occurs on copper (see below for details).
This filler metal should not be used to braze iron containing materials like carbon or stainless steels or nickel
containing materials as the phosphorus within the filler metal will form brittle, inter-metallic, phosphide compounds
at the joint interface. Copper-flo™ No.3 is not suitable for use in joints exposed to sulphurous atmospheres at
elevated service temperatures.
When selecting a copper-phosphorus brazing filler metal it is necessary to understand about their flow properties
and ductility. The level of phosphorus within the filler metal controls these two characteristics - the higher this is the
more free flowing the filler metal and the lower its ductility.
Copper-flo™ No.3 due to its lower phosphorus content is less free flowing and slightly more ductile than Copperflo™.
It has a long melting range and a tendency to liquate. This property can be used to aid bridging of
comparatively wide joint gaps. Copper-flo™ No.3 is suited for joint clearances of 0.75-0.2 mm.
Composition: 93.8Cu, 6.2%P
Conforms to: EN 1044 1999 CP203, ISO 17672:2010 CuP 179
Melting range: 714-890˚C*
*The flow point for this filler metal is below the liquidus temperature.
Uses for This Product
Copper-flo™ No.3 is widely used for brazing copper pipes, tubes and fittings in the refrigeration, heating and
ventilating and air conditioning systems. PLEASE NOTE RODS WILL BE CURLED UP FOR POST.