AGL_Unit_ZX_Small_E_Rev03
11
IMPORTANT
Connection sizes! Unsuitable refrigerant flow rate!
Do not assume that
the service connection sizes on the unit (at the service valves) are in fact 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 piping should be sized to satisfy the duty required.
IMPORTANT
Absence of insulation on the liquid line in ZXLE units! Air moisture
condensation and lack of performance!
Moisture will condensate on the
liquid line and cause water droplets. The liquid line can pick up additional
heat from the ambient which will adversely affect the subcooling desirable for
the liquid refrigerant before it enters the expansion valve. Both the suction
and liquid interconnecting piping between the unit and the evaporator should
be insulated to avoid condensation.
The piping 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 to 1/250. Upper and lower oil 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
Table 10
below:
Tube size
Max distance between
2 clamp supports
1/2" (12.7 mm)
1.20 m
5/8" (16.0 mm)
1.50 m
7/8" (22.0 mm)
1.85 m
1 1/8" (28.5 mm)
2.20 m
Table 10: Maximum distance between 2 clamp supports
3.2.2
Brazing
recommendations
CAUTION
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.
Contamination or moisture!
Bearing failure!
Do not remove the plugs until
the compressor is set into the unit. This minimises any entry of contaminants
and moisture.
▪
Remove the discharge connection cap.
▪
Remove the suction connection cap.
▪
Open both valves mid-way. Care should be taken to avoid the holding charge releasing too
quickly.
▪
Be sure tube fitting inner surface and tube outer surface are clean prior to assembly.
▪
Both tubes are extended from the refrigeration unit housing, therefore we recommend isolating
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 a silver
alloy rod either flux coated or with a separate flux would be used.
▪
Use a double-tipped torch.
