Piping; General - Liebert DM User Manual

14 Chapter 2 Mechanical Installation

2.6 Piping

All joints of the cooling pipes must be silver brazed. Standard industry procedures must be followed in selecting, laying,
and fixing the pipes, and in vacuuming the system and charging refrigerant. Take pipeline pressure drop, oil return to
the compressor and minimization of noise and vibration into consideration during the design and construction.

2.6.1 General

The recommended pipe sizes are 'equivalent lengths' (see Table 2-5 for equivalent lengths of partial components),
which has included the resistance brought about by bends. You should confirm that the sizes are appropriate for the
site conditions.
1. If the one-way equivalent length exceeds 30m, or if the vertical difference between indoor unit and outdoor unit
exceeds the values in Table 2-5, consult the factory before installation for confirmation whether extended components
are needed.
Indoor unti lower than outdoor unit
Outdoor unit lower than indoor unit
2. The pipe sizes recommended in Table 2-6 are 'equivalent lengths', which has included the resistance brought about
by bends and valves. You should confirm that the sizes are appropriate for the site conditions.
Outer Diameter (OD) of
liquid pipe (inch)
3/8
1/2
5/8
3/4
7/8
1-1/8

Note
A trap is required for every 7.5m of vertical lift. Please consult the factory for detailed information.
Connecting pipes
The pipes to connect include:
1. Cooling water drain-pipe of indoor unit
2. Water supply pipe of infrared humidifier
3. Connecting copper pipe (exhaust pipe and liquid return pipe) between indoor unit and outdoor unit
4. Installing extension subassembly (optional)
 Connecting cooling water drain-pipe of indoor unit
The cooling water of infrared humidifier and evaporator is converged by the cross connector and drains through the
draining pipe, as shown in Figure 2-19. The OD of the pipe is 25mm. If the draining pipe is used by three or more units,
the minimal OD of the pipe should be 40mm.

Note
Because the humidifier contains boiling water, the plastic pipe must be rated higher than 90℃.
Table 2-5 Vertical difference between indoor unit and outdoor unit
Relative position
Table 2-6 Equivalent lengths of partial components
90° bend
0.21
0.24
0.27
0.3
0.44
0.56
DM Series 16kW Air Conditioner User Manual
Value
Max.: +20m
Max.: -5m
Equivalent length (m)
45° bend
0.10
0.12
0.15
0.18
0.24
0.3
T type three way
0.76
0.76
0.76
0.76
1.1
1.4