Vertiv Liebert MC series Installer/User Manual Download

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Consult local building and plumbing codes for installation requirements of additional pressure relief devices when isolation
valves are field installed. Do not isolate any refrigerant circuits from over pressurization protection.

NOTICE

Risk of oil contamination with water. Can cause equipment damage.

Polyolester oil (POE oil), required with R-407C/R-410A and used with some R-22 systems, is much more
hygroscopic than mineral oils. This means that POE oil absorbs water at a much faster rate when exposed to air
than previously used mineral oils. Because water is the enemy of a reliable refrigeration system, extreme care
must be used when opening systems during installation or service. If water is absorbed into the POE oil, it will
not be easily removed and will not be removed through the normal evacuation process. If the oil is too wet, it
may require an oil change. POE oils also have a property that makes them act as a solvent in a refrigeration
system. Maintaining system cleanliness is extremely important because the oil will tend to bring any foreign
matter back to the compressor or plug the microchannel coil. Always use a flow of dry nitrogen when brazing.

5.1.1 Refrigerant Piping Guidelines for Air Cooled Systems

•

Air cooled units and condensers ship with an inert gas holding charge. Do not vent the charge until all
refrigerant piping is in place, ready for connection to the unit and condenser.

•

Use copper piping with a brazing alloy with a minimum temperature of 1350°F (732°C), such as Sil-Fos. Avoid
soft solders, such as 50/50 or 95/5.

•

Use a flow of dry nitrogen through the piping during brazing to prevent formation of copper oxide scale inside
the piping. When copper is heated in the presence of air, copper oxide forms. POE oils will dissolve these
oxides from inside the copper pipes and deposit them throughout the system, clogging filter driers and
affecting other system components.

•

A pure dry nitrogen flow of 1-3 ft.

/min (0.5-1.5 l/s) inside the pipe during brazing is sufficient to displace the air.

Control the flow using a suitable measuring device.

•

Ensure that the tubing surfaces to be brazed are clean and that all burrs have been removed from the ends of
the tubes.

•

Ensure that all loose material has been cleaned from inside the tubing before brazing.

•

Protect all refrigerant line components within 18 in. (460 mm) of the brazing site by wrapping them with a wet
cloth or with a suitable heat sink compound.

•

Isolate piping from building using vibration isolating supports.

•

Consult factory if piping run exceeds 150 ft. (46 m) equivalent length on traditional R-407C DX units.

•

Consult factory if piping run exceeds 300 ft. (91 m) equivalent length on traditional R-410A DX units.

•

Consult factory if piping run exceeds 300 ft. (91 m) actual length or 450 ft. (137.2 m) equivalent length on units
with Liebert® EconoPhase units.

•

Install traps on hot gas (discharge) lines at the base of vertical risers over 5 ft. (1.5 m) and then for vertical rises
over 25 ft. (7.6 m), install a trap in 20 ft. (6 m) increments or evenly divided over the vertical rise.

•

Pitch horizontal hot gas piping down at a minimum rate of 1/2 in. per 10 ft. (42 mm per 10 m) so that gravity will
aid in moving oil in the direction of refrigerant/oil flow.

•

Keep piping clean and dry, especially on units with R-410A or R-407C refrigerant.

•

Avoid piping runs through noise sensitive areas.

•

Do not run piping directly in front of indoor unit discharge air stream.

•

Refrigerant oil – do not mix oil types. Consult the indoor unit installation/user guide for refrigerant type and oil
requirements.

Vertiv | Liebert® MC Installer/User Guide