4.5 Piping Details—Shutoff/Isolation Valves
Isolation valves must be installed on the Liebert XDC’s refigerant circuit to permit maintenance on the
unit (see Figure 4.5 below.)
Figure 4.5 General piping details
Evacuation and Leak Check—R-134a Pumped Circuit
1. Open all service valves, including those located outside of the Liebert XDC.
2. Attach a jumper hose from one of the Schrader valve fittings on a pump outlet before the
check valve to a Schrader valve fittings after the check valve.
3. Place 150 psig (1034kPa: 10.34 bars) of dry nitrogen with a tracer of R-134a in the system.
NOTE: Risk of overpressurization. Can cause equipment damage.
Do not exceed 150 psig (1034 kPa; 10.34 bars) in the R-134a circuit.
4. Check the system for leaks with a suitable leak finder on the pumps’ suctions lines.
5. After completion of the leak testing, release the test pressure (per local code) and connect to
vacuum pump(s) at the Schrader valves.
6. After four hours of pulling a deep vacuum, check the vacuum level and if it has not changed,
break the vacuum with dry nitrogen.
7. Pull a second vacuum to 500 microns or less. Recheck the vacuum level after 2 hours.
Insulation
NOTE: Piping should not be insulated before it has been checked for leaks. Applying good insulation
to pipes before checking for leaks would prevent easy detection of leaks.
Insulate all piping between the Liebert XDC and cooling modules to prevent condensation where the
piping passes through non-conditioned areas.
4.6 Filling the Pumped Circuit—R-134a
1. Connect a charging manifold to the Schrader valve fittings on the pump suctions lines.
Vertiv | Liebert® XDC™ User Manual | 41
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