Trane CAUC-C20, Установка, эксплуатация и обслуживание

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Installation (Continued)
present, relieve the pressure before attempting to unsweat
the “seal” caps. If refrigerant connections are not capped,
but are “spun-end” tubes, use a tubing cutter to remove the
end from the pipe.
Note: To prevent damage to the system, do not drill
a hole in the seal caps or saw the ends off pipe
stubs. This may introduce copper chips into the
system piping.
Brazing Procedures
Proper brazing techniques are essential when installing re-
frigerant piping. The following factors should be kept in
mind when forming sweat connections.
1. When copper is heated in the presence of air, Copper ox-
ide forms. To prevent copper oxide from forming inside
the tubing during brazing, sweep an inert gas, such as
dry nitrogen, through the tubing. Nitrogen displaces air in
the tubing and prevents oxidation of the interior surfaces.
A nitrogen flow of one to three cubic feet per minute is
sufficient to displace the air. Use a pressure regulating
valve or flow meter to control the flow.
USE NITROGEN ONLY TO PURGE THE SYSTEM
WHILE SWEATING CONNECTIONS.
Failure to follow proper procedures can result in per-
sonal injury or death due to a possible formation of
an explosive mixture of R-22 and air and/or inhala-
tion of phosgene gas.
2. Ensure that the tubing surfaces to be brazed are clean,
and that the ends of the tubes have been carefully
reamed to remove any burrs.
3. Make sure the inner and outer tubes of the joint are sym-
metrical and have a close clearance, providing an easy
slip fit. If the joint is too loose, the tensile strength of the
connection will be significantly reduced. The overlap dis-
tance should be equal to the diameter of the inner tube.
4. Wrap the body of each refrigerant line component with a
wet cloth to keep it cool during brazing. Move any tube
entrance grommets away for the brazing area.
Note: Use 40 to 45% silver brazing alloy (BAg-7 or
BAg-28) on dissimilar metals. Use BCup-6 brazing
alloy on copper to copper joints.
5. If flux is used, apply it sparingly to the joint. Excessive
flux can enter the system which will contaminate the re-
frigerant system.
6. Apply heat evenly over the length and circumference of
the joint to draw the brazing material into the joint by
capillary action. Remove the brazing rod and flame from
the joint as soon as a complete fillet is formed to avoid
possible restriction in the line.
7. Visually inspect the connection after brazing to locate
any pin holes or crevices in the joint. The use of a mirror
may be required, depending on the joint location.
A double riser system may be necessary to meet the dis-
charge line velocity requirements.
When either a single or double discharge riser is used, the
line should drop well below the discharge outlet of the com-
pressor before starting the vertical rise to prevent the possi-
bility of refrigerant draining back to the compressor during
the “Off” cycle.
Table 3-2
Minimum Vertical Line Velocities
Line Minimum
Dia. Velocity (fpm)
7/8" 470
1-1/8" 540
1-3/8" 600
1-5/8" 650
2-1/8" 750
2-5/8" 825
3-1/8" 915
3-5/8" 975
Discharge (Hot Gas) Line Components
Field supplied hot gas mufflers, pipe anchors, single or
double risers, oil traps, etc. as applicable, should be provide
to prevent excessive line vibration and assure proper oil re-
turn to the compressor for proper system operation.
A field supplied discharge “shutoff” valve in each hot gas
line near the condenser is recommended to facilitate refrig-
erant storage in the condenser during service procedures.
A “constant drain” oil trap is illustrated below and can be
used as an alternative to a double riser application. The
constant drain oil trap assures adequate oil return to the
suction line even at part load conditions. Refer to “Recipro-
cating Direct Expansion Piping Systems” (AM-REF 1/82) for
suggested piping arrangement details.
Final Refrigerant Pipe Connections
To access the refrigerant pipe connections, remove the lou-
vered side grills. Refer to Figure 3-2.
These condensing units are shipped with a Nitrogen hold-
ing charge. Install pressure gauges to the appropriate ac-
cess valve(s) and take a reading. If no pressure is present,
refer to the “Leak Testing Procedure” section. If pressure is
Oil Trap
Drip Leg
Hot Gas
1/4" Solenoid
Filter
Oil Return
Line
5 feet of 1/8"
Copper Tubing
Valve