Installation manual

Air Cooled Models
20
3.3 Refrigerant Piping
All refrigeration piping should be installed with high temperature brazed joints. Prevailing good
refrigeration practices should be employed for piping supports, leak testing, dehydration and charg-
ing of the refrigeration circuits. The refrigeration piping should be isolated from the building by the
use of vibration isolating supports. Piping, including inverted trap(s), must be routed to allow
unobstructed access to the panel per the NEC.
Traps should be installed in the hot gas lines on vertical risers every 25 feet (7.6 meters) in elevation.
These traps will collect condensed refrigerant and refrigerant oil during the off cycle of the unit and
ensure flow of refrigerant oil during operation. Hot gas vertical risers may require downsizing of the
line to provide for adequate refrigerant velocities to move oil up the riser. This is especially true on
systems with unloaders.
Contact your local Liebert representative for factory approval whenever a refrigerant piping run
exceeds 200 feet (60 meters) equivalent length or when condensers must be located below the level of
the cooling coil.
Table 8 Recommended line sizes – O.D. copper
75A 114A (115A) 125A (130A) 199A 245A 290A 380A
Hot Gas
Line
Liq.
Line
Hot Gas
Line
Liq.
Line
Hot Gas
Line
Liq.
Line
Hot Gas
Line
Liq.
Line
Hot Gas
Line
Liq.
Line
Hot Gas
Line
Liq.
Line
Hot Gas
Line
Liq.
Line
50 ft
(15m)
5/8 1/2 7/8* 1/2 7/8* 1/2 7/8 5/8 1-1/8* 7/8 1-1/8 7/8 1-3/8 7/8
100 ft.
(30m)
7/8 1/2 7/8* 5/8 7/8 5/8 1-1/8* 7/8 1-1/8 7/8 1-1/8 7/8 1-3/8 7/8
150 ft.
(45m)
7/8 5/8 7/8 5/8 7/8 5/8 1-1/8 7/8 1-1/8 7/8 1-1/8 7/8 1-3/8 1-1/8
*With 4-Step Models, use one (1) trade size smaller (7/8 = 3/4, 1-1/8 = 7/8).
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