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Refrigeration Piping Installation
All interconnecting pipes should be of refrigeration grade, clean, dehydrated and must remain capped at both ends until installation.
Even during installation, if the system is left for any reasonable period of time (say two hours), pipes should be re- capped to prevent
moisture and contaminants from entering the system.
Do not assume that the service connection sizes on the unit (at the service valves) are the correct size to run your interconnecting
refrigeration pipes. The service valve sizes have been selected for convenience of installation and in some cases (larger units) these
may be considered too small. However for the very short pipe run within our units, these service connection sizes are adequate. All
interconnecting pipes should be sized to satisfy the duty required.
Usually the suction line is insulated, but the liquid line is not. However the liquid line can pick up additional heat from the ambient and
adversely affect the sub-cooling desirable for the liquid refrigerant before it enters the expansion valve.
The pipe should be sized to ensure optimum performance and good oil return. The sizing must also take into account the full capacity
range through which this particular unit will need to operate.
Pipe runs should be kept as short as possible, using the minimum number of directional changes. Use large radius bends and avoid
trapping of oil and refrigerant. This is particularly important for the suction line. The suction line should ideally slope gently towards the
unit. Recommendation slope is 1/200~1/250. P traps, double risers and reduced pipe diameters may be required for suction lines where
long vertical risers cannot be avoided. All pipes should be adequately supported to prevent sagging which can create oil traps.
The recommended pipe clamp support distance is shown in the table.
Tube Size
12.7mm (1/2 inch)
16.0mm (5/8 inch)
22.0mm (7/8 inch)
28.5mm (1 1/8 inch)
ZXL Liquid Line Insulation
ZXL liquid line should be insulated with a 19 mm insulation thickness. Temperature could be as low as –15°C.
Brazing Recommendations
Maintain a flow of oxygen-free nitrogen through the system at a very low pressure during brazing. Nitrogen displaces the air and prevents
the formation of copper oxides in the system. If copper oxidization is 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. This minimizes any entry of contaminants and moisture.
• Remove the liquid line connection cap.
• Then remove the suction connection cap.
• Open both valves midway. Care should be taken to avoid the
holding charge from releasing too quickly.
• Be sure tube fitting inner diameter and tube outer diameter
are clean prior to assembly.
• Since both tubes are extended from the condensing unit housing,
we recommend insulating the housing by using a wet cloth on the
copper tubing.
• 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, use a silver alloy
rod, either flux coated or with a separate.
• Use a double tip torch.
16
Max distance between
2 clamp support
1.20 m
1.50 m
1.85 m
2.20 m
OUTSIDE
End of Tube
During brazing
protect housing
with damp cloth
INSIDE UNIT
During brazing
pull back fire
insulation
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