Technical information

12 C6.1.7/0609-1110/E
3.4 Refrigeration connections
IMPORTANT
Blockage! Compressor breakdown! Maintain a flow of oxygen-free
nitrogen through the system at very low pressure during brazing. Nitrogen
displaces the air and prevents the formation of copper oxides in the system.
If allowed to form, the copper oxide material can later be swept through the
system and block screens such as those protecting capillary tubes, thermal
expansion valves, and accumulator oil return holes.
3.4.1 Brazing recommendations
 Remove the fishtails (= compressed tube ends) by cutting them off in the following
sequence:
1. Remove the discharge connection fishtail;
2. Then remove the suction connection fishtail.
Removing the plugs in this sequence prevents oil mist from coating the suction tube
making brazing difficult.
 Be sure tube fitting inner diameter and tube outer diameter are clean prior to assembly.
 Recommended brazing materials: a copper/phosphorous or copper/phosphorous/silver
alloy rod should be used for joining copper to copper whereas to join dissimilar or ferric
metals a silver alloy rod either flux coated or with a separate flux would be used.
 Use a double-tipped torch.
3.4.2 Brazing procedure
For brazing of the tubes, please refer to illustration and procedure hereunder:
1. Fit the copper tube into the compressor tube.
2. Heat area 1. As the tube approaches brazing temperature:
3. Heat area 2 until braze temperature is attained. It is
necessary to heat the tube evenly. Move the torch up and down
and rotating around the tube.
4. Add braze material to the joint while moving the torch
around the joint to flow braze material around the circumference.
5. Then heat area 3. This will draw the brazing material down
into the joint.
Figure 8: Suction tube brazing
NOTE: The time spent heating area 3 should be minimal. As with any brazed joint,
overheating may be detrimental to the final result.
To disconnect:
Heat joint areas 2 and 3 slowly and uniformly until solder softens and tube can be pulled out of
the fitting.
To reconnect:
See the procedure above.
3.5 Electronic controller EC2-552
The EC2-552 electronic condensing unit controller is mounted as standard in Digital Receiver
HLR units.
 receiver units with single compressor
 receiver units with two compressors