61
(Reference)
Melting temperature of copper • • • • • • • Approx. 1083°C
Maximum temperature obtained in propane and oxygen • • • • • • • Approx. 1083°C
The important point is to heat the bonding part uniformly within a short period of time until reaching to the brazing
temperature in the following manner.
2. Apply the flame on to the side with better heat transmission. If the pipe thickness is consistent, by heating like
30% iron and 70% copper, the copper pipe inside reaches to brazing temperature.
Iron pipes have low heat transmission and only the part the flame is applied get high temperature, and this
causes oxidization of the pipe. The flow of the brazing filler is affected negatively.
3. Apply the flame on to the side of larger heat
capacity.
When brazing a thin tubes such as capillary tube
and dryer, etc., caution has to be taken to apply
the flame to the dryer side (thick pipe side), in
order to prevent burn out by the heat.
4. When brazing the compressor connection pipes
(suction and discharge), remove the sound
insulation plate and the fan, and place the
compressor stand vertically (to prevent the
leakage of compressor refrigerating machine oil),
and apply the flame from the compressor body
side.
12.7.12 Terminologies of brazing
Pin holes → Small holes are generated on the surface of the brazing metal.
Wet temperature → Liquidus temperature at which the brazing material starts flowing out by heating, generally it is
the liquidus-line temperature.
Blow holes → Hollows made by gas in the brazing material of brazing portion (gas reservoirs).
Pits → As a result of blow holes, small dents generated on the outside surface of welding.
Voids → The blazing material does not reach completely to the brazing part. It cannot be identified from outside.
