R410A Precharge Air - Cooled (A) Units; Refrigerant Charge Air; Refrigeration Circuits - Emerson Liebert CRV User Manual

4.2.1

R410A precharge Air - cooled (A) units

1) Open all cocks of the system including those used for pressurizing (ambient unit and condens-
ing unit).
By this operation all the components of the refrigerating circuit must be subject to vacuum.
2) Connect a proper, high efficiency vacuum pump (10) suitable for polyester oils to the coup-
lings:
- Compressor intake and delivery using, if available, the three-way Rotalock cocks, coup-
ling 1/4" SAE (make sure that all three ways are open), otherwise the Schrader valves
brazed on the pipings.
- Coupling 1/4" SAE of the liquid receiver (12).
- Coupling 1/4" SAE of the evaporator coil (14).
3) Provide for a connection with refrigerant cylinder before making vacuum.
4) Make the system vacuum up to 0.3 absolute mbar and after 3 hours check if 1.3 absolute mbar
have not been exceeded. This condition warrants a humidity lower than 50 ppm inside the sys-
tem.
If the complete vacuum is not possible, this means that there are some leaks (to be removed
according to the instructions in 6 below).
NEVER USE THE COMPRESSOR TO CREATE A VACUUM (THIS INVALIDATES ITS
GUARANTEE).
5) Break the vacuum as follows:
a) Close the cock (10a) for the vacuum pump (10).
b) Open the cock of the refrigerant cylinder (11a) until the system reaches a pressure value
of about 1 bar. Repeat this procedure using a Schrader valve on high pressure side near
liquid receiver.
c) At this point both the vacuum pump and the refrigerant cylinder can be disconnected as
follows:
c1)close the cylinder cock (11a)
c2)close the way 1/4" SAE of the Rotalock cocks and of the connected Schrader valves.
6) Inspect all connections/joints using a leak detector. If a leak is found, empty the pipes and the
condenser, seal the leak and repeat the instructions in 3) - 6).
7) Now the machine is ready for completing the charge and the start-up.
8) Charge the refrigerant (ONLY LIQUID) by means of the charge valve placed at the evaporat-
or inlet.
4.2.2 Refrigerant charge Air - cooled (A) units
1) Start the unit as described in para. 7.1.
2) Manually start the compressor at 100% modulation (ensure the unit is not in the dehumidific-
ation phase).
3) Guarantee a constant condensation temperature (preferably 45°C); if necessary, partially ob-
struct the condenser coil surface or limit its ventilating power to obtain these conditions.
4) Charge the unit until the working conditions of the entire refrigeration circuit have become
normal.
5) Using a manometer, check that the evaporating temperature is above 0_C.
6) Verify that the superheat is 5-8 K (to do this refer to para. 9.1).
4.3

Refrigeration circuits

See drawings in Enclosure E.
The refrigerant must be introduced and charged by taking only liquid fluid from the
cylinder.
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Refrigeration Connections