Vertiv Liebert DSE, System Design And User Manual

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8.2.6 Evacuation, Leak-testing, and Charging Air-cooled Systems
Two discharge lines and two liquid lines must be field-installed between the indoor unit and the outdoor
condenser.
NOTE: Keep the evaporator unit, and condenser closed with their factory charge of dry nitrogen while
all field piping is installed. Keep the field piping clean and dry during installation. Do not allow it to stand
open to the atmosphere. When all the field interconnecting piping is in place, vent each outdoor unit’s
dry nitrogen charge and connect to the field piping. Finally, vent the evaporator unit's dry nitrogen
charge and make its piping connection last. Follow all proper brazing practices, including a dry nitrogen
purge to maintain system cleanliness. The condenser connection pipes must be wrapped with a wet
cloth to keep the pressure and temperature sensors cool during any brazing.
Evacuation and Leak-testing Air-cooled Systems
For proper leak-check and evacuation, you must open all system valves and account for all check valves.
NOTE: The system includes a factory-installed check valve and an additional downstream Schrader
valve with core in the compressor discharge line. Proper evacuation of the condenser side of the
compressor can be accomplished only using the downstream Schrader valve. See the appropriate
piping schematic for your system in Submittal Drawings on page 67.
1. Starting with Circuit #1, open the service valves and place a 150 PSIG (1034 kPa) of dry
nitrogen with a tracer of refrigerant. Check system for leaks with a suitable leak detector.
2. With pressure still in Circuit #1, open the compressor service valves in Circuit #2.
• If pressure increases in Circuit #2, the system is cross-circuited and must be re-checked
for proper piping.
• If there is no pressure increase, repeat step 1 on Circuit #2.
3. After completion of leak testing, release the test pressure, (observe local code) and pull an
initial deep vacuum of 500 microns on the system with a suitable pump.
4. After 4 hours, check the pressure readings and, if they have not changed, break vacuum with
dry nitrogen. Pull a second and third vacuum to 500 microns or less. Re-check the pressure
after 2 hours.
When the 3 checks are complete, remove the jumper hose from the service-valve fitting and
the condenser, and proceed to Charging Air-cooled Systems below.
Charging Air-cooled Systems
NOTICE
Risk of improper refrigerant charging. Can cause equipment damage.
R-410A is a blended refrigerant and must be introduced and charged from the cylinder only as
a liquid.
When adding liquid refrigerant to an operating system, it may be necessary to add the
refrigerant through the compressor suction service valve. Care must be exercised to avoid
damage to the compressor. We recommend connecting a sight glass between the charging
hose and the compressor suction service valve. This will permit adjustment of the cylinder
hand valve so that liquid can leave the cylinder while allowing vapor to enter the compressor.
NOTICE
Risk of improper operation. Can cause compressor failure.
Operating the unit with the EEV closed can cause compressor failure. The reheat and
humidifier are disabled. A minimum of 20 psig (138 kPa) must be established and maintained
for the compressor to operate. The charging function can be reset as many times as required
to complete
Vertiv | Liebert® DSE™ System Design and User Guide
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