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Designing a Liebert XD Solution
28
3.16.2 Calculating Refrigerant Charge—Example
Using Tables 7, 8, 9 and 10, calculate the refrigerant charge of the individual sections of your Liebert
XD system. Add the calculated charge amounts to determine the amount of R-134a refrigerant
required for one system combining a Liebert XDP with Liebert XD cooling modules (Liebert XDCF,
Liebert XDH, Liebert XDO and Liebert XDV). The example below combines one Liebert XDP with 20
Liebert XDV8 cooling modules.
Verify that the refrigerant volume of the Liebert XD system with the longest piping length is within
the allowable limit. If the allowable limit is exceeded, the Liebert XDP/Liebert XDC should be moved
closer to the cooling modules (refer to 3.12 - Liebert XD Refrigerant for limits and related details).
Another way to shorten the total pipe length is to reroute the pipe runs.
3.17 Liebert XDC DX R-407c Circuit Volume—Air Cooled Units
Weigh in the calculated charge based on Tables 13, 14 and 15.
Table 11 Calculating refrigerant charge—example
Components
Number of Units
or Piping Length, feet Pounds Per Component Total, lb.
Liebert XDP/Liebert XDC 1 157 157
Liebert XDV8 Cooling Modules 20 2.32 46.4
Supply Main, 1-1/8" 100 0.45 45
Return Main, 2-1/8" 100 0.28 28
Liebert XDV 1/2" supply Flex
Pipes
20 0.8 16
Liebert XDV 5/8" return Flex
Pipes
20 0.03 0.6
Total 293
Table 12 Worksheet to calculate refrigerant charge
Components
Number of Units
or Piping Length Pounds Per Component Total
Total
!
CAUTION
Risk of improper lubrication. May cause equipment damage.
Liebert XDCs with refrigerant R-407c charges over 35 lb. (15.9kg) require additional oil. Refer
to the Liebert XDC user manual, SL-16671, available at Liebert’s Web site,
www.liebert.com
Table 13 Indoor unit refrigerant charge—R-407c
Model 60/50 Hz Charge/Circuit, lb. (kg)
Liebert XDC160 17.5 (8.0)