SCXF-SVX01B-EN
25
Refrigerant Piping (Air-Cooled
Units Only)
The maximum line pressure design of
each refrigerant circuit is 3 psig. Include
the following items when designing
refrigerant piping: oil traps, dual risers, oil
return, etc. Refer to the
Trane
Reciprocating Refrigeration Manual for
proper line sizing and layout.
See the “Start Up” section of page 57 of
this manual for instructions on refrigerant
evacuation, charging, and superheat
measurement. Leak-test the entire
refrigeration system after all piping is
complete.
Leak Test (Remote Air-cooled Units
Only)
Units ship with a holding charge of dry
nitrogen. Before installing the unit
refrigerant piping, momentarily depress
either the suction or discharge line access
valve to verify the holding charge has not
been lost. If no nitrogen escapes the
access valve, leak-test the entire
refrigerant system to determine the leak
source. Use a halogen leak detector, a
halide torch, or soap bubbles to leak test.
After finding a leak, remove the test
pressure and repair the leak. Retest the
unit to ensure all leaks are repaired.
Brazing Procedures
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.
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.
10. Reference Tables O-M-3 and O-M-4
on page 88 for the correct amount of
refrigerant required for charging the
unit.
Mechanical
Requirements
Installation
