Piping and Filling with Refrigerant: R-134a and R-407c Circuits
19
Figure 22 Bypass flow controller piping
Evacuation and Leak Check—R-134a Pumped Circuit
1. Open all service valves, including those located outside of the Liebert XDC.
2. Place 150 psig (1034kPa: 10.34 bars) of dry nitrogen with a tracer of R-134a in the system.
3. Check the system for leaks with a suitable leak finder
4. After completion of the leak testing, release the test pressure (per local code) and connect to
vacuum pump(s) at the Schrader valves.
5. After four hours of pulling a deep vacuum, check the vacuum level and if it has not changed,
break the vacuum with dry nitrogen.
6. Pull a second vacuum to 250 microns or less. Recheck the vacuum level after 2 hours.
Insulation
Insulate all piping between the Liebert XDC and cooling modules to prevent condensation where the
piping passes through non-conditioned areas.
!
CAUTION
Risk of overpressurization. Can cause equipment damage.
Do not exceed 150 psig (1034 kPa; 10.34 bars) in the R-134a circuit.
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.
Filter Dryer
Assembly
Liebert XD
Cooling
Module #1
Liebert XD
Cooling
Module #2
Coolant
Supply
Coolant
Return
Bypass Flow
Controllers
Liebert XDP
or
Liebert XDC