Vertiv Liebert XD Series, System Design Manual

Page: 135 / 200

NOTICE
Risk of improper compressor lubrication. Can cause compressor and refrigerant system damage.Failure to
use oil types, viscosities and quantities recommended by the compressor manufacturer may reduce
compressor life and void the compressor warranty.
• Do not mix polyol ester (POE) and mineral-based oils.
• Do not mix oils of different viscosities.
Consult Vertiv Technical Support or the compressor manufacturer if questions arise.
6.6 Liebert Drycoolers
The Liebert drycooler is a low-profile, direct-drive propeller fan-type air cooled unit. Constructed with an
aluminum cabinet and a copper-tube aluminum fin coil, the unit is quiet and corrosion resistant. All
electrical connections and controls are enclosed in an integral NEMA 3R rated electrical panel section of
the drycooler.
6.6.1 Liebert Drycooler Fan Cycling Control
Available on all sizes of standard sound and Quiet-Line drycoolers. A thermostatic control cycles the fan
on a single-fan drycooler in response to leaving fluid temperatures. Two or more thermostats are
employed on drycoolers with two or more fans to cycle fans or groups of fans in response to leaving fluid
temperatures. The thermostat setpoints are listed on the factory-supplied schematic. They typically
range from 35 to 45°F (2 to 7°C) for GLYCOOL applications and 65 to 75°F (18 to 24°C) for glycol
applications.
6.6.2 Pump Controls
Controls for pump(s) up to 7.5hp are built into the same integral electric panel as the drycooler fan
controls. Pump fuses, overload heaters and flow switch (dual pump control models) are included with the
Liebert pump packages or must be field-supplied for field-supplied pumps.
Dual pump option—Provides controls for primary and standby pump. The flow switch senses loss of flow
and switches to the standby pump for continuous system operation in the event of a pump failure. An
internal switch allows manual selection of the lead/lag pump.
6.7 Typical System configurations
The standard glycol-cooled precision air conditioning system includes these major components:
• indoor air conditioning unit with heat exchangers (refrigerant/glycol)
• glycol regulating valve
• outdoor air cooled drycooler
• glycol pump(s)
• expansion/compression tank
• pump controls
• interconnection piping
• unit interlock control wiring
Figure 6.12 on the next page shows a typical configuration of multiple indoor units and multiple outdoor
drycoolers using a dual pump package and on a common piping loop.
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