Trane IntelliPak SCRF 25, Installation, Operation And Maintenance Manual

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SCXF-SVX01Q-EN 93
System Repair
1. If system is water cooled with service valves, or air
cooled, high and low side may be tested
independently by closing liquid line angle valve and
water cooled unit discharge line ball valve.
Otherwise leave all valves open and DO NOT
exceed low side design pressure.
2. Connect R-410A refrigerant cylinder to charging
port, add refrigerant to reach pressure of 12 to 15
psig.
3. Disconnect refrigerant cylinder. Connect dry
nitrogen cylinder to high side charging port and
increase pressure to 150 psig. DO NOT exceed unit
nameplate design pressures. If testing complete
system, low side design pressure is maximum.
4. Check piping and/or components as appropriate for
leaks.
5. Recommend using electronic detector capable of
measuring 0.1 oz/year leak rate.
6. If a leak is located, use proper procedures to
remove the refrigerant/nitrogen mixture, break
connections and make repairs. Retest for leaks.
7. Make sure all service valves are open.
Brazing Procedures
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Proper brazing techniques are essential when installing
refrigerant piping. The following factors should be kept
in mind when forming sweat connections:
1. When heating copper in the presence of air, copper
oxide forms. To prevent copper oxide from forming
inside the tubing during brazing, sweep an inert
gas, such as dry nitrogen, through the tubing. A
nitrogen flow of 1 to 3 cubic feet per minute is
sufficient to displace the air in the tubing and
prevent oxidation of the interior surfaces. Use a
pressure regulating valve or flow meter to control
the flow.
2. Ensure that the tubing surfaces requiring brazing
are clean, and that the tube ends are carefully
reamed to remove any burrs.
3. Make sure the inner and outer tubes of the joint are
symmetrical and have a close clearance, providing
an easy “slip” fit. If the joint is too loose, the
connection’s tensile strength is significantly
reduced. Ensure the overlap distance is equal to the
inner tube diameter.
4. Wrap each refrigerant line component with a wet
cloth to keep it cool during brazing. Excessive heat
can damage the internal components.
N No otte e:: Use 40-45% silver brazing alloy (BAg-7 or
BAg-28) on dissimilar metals. Use BCup-6
brazing alloy on copper-to-copper joints.
5. If using flux, apply it sparingly to the joint. Excess
flux will contaminate the refrigerant system.
6. Apply heat evenly over the length and
circumference of the joint.
7. Begin brazing when the joint is hot enough to melt
the brazing rod. The hot copper tubing, not the
flame, should melt the rod.
8. Continue to apply heat evenly around the joint
circumference until the brazing material is drawn
into the joint by capillary action, making a
mechanically sound and gas-tight connection.
9. Visually inspect the connection after brazing to
locate any pinholes or crevices in the joint. Use a
mirror if joint locations are difficult to see.
System Evacuation Procedures
• Each refrigeration circuit must be evacuated before
the unit can be charged and started.
• Use a rotary type vacuum pump capable of pulling
a vacuum of 100 microns or less.
• Verify that the unit disconnect switch and the
system control circuit switches are “OFF”.
• Oil in the vacuum pump should be changed each
time the pump is used with high quality vacuum
pump oil. Before using any oil, check the oil
container for discoloration, which usually indicates
moisture in the oil and/or water droplets. Moisture
in the oil adds to what the pump has to remove
from the system, making the pump inefficient.
• When connecting vacuum pump to refrigeration
system, it is important to manifold vacuum pump to
both high and low side of system (liquid line access
valve and suction line access valve). Follow pump
manufacturer’s directions for proper methods of
using vacuum pump.
• Lines used to connect the pump to the system
should be copper and of the largest diameter that
can practically be used. Using larger line sizes with
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