Precharging Refrigerant

Procedure

1. Remove the vacuum pump from the vacuumizing equipment, and replace the vacuum pump with a refrigerant cylinder, as shown in Figure 6-3 or Figure 6-4.
   Figure 6-3 Precharging refrigerant when no low temperature component is configured
   

   (1) Refrigerant cylinder	(2) Electronic scale	(3) Pressure gauge
   (4) Connection nut	(5) Low-pressure needle valve	(6) Discharge pipe needle valve

   Figure 6-4 Precharging refrigerant when a low temperature component is configured
   

   (1) Refrigerant cylinder	(2) Electronic scale	(3) Pressure gauge 1	(4) Pressure gauge 2
   (5) Connection nut	(6) Low-pressure needle valve	(7) Discharge pipe needle valve	(8) Liquid pipe needle valve

2. Slightly open the refrigerant cylinder valve and loosen the connection nut of the pressure gauge. Tighten the nut when cold air escapes out of the nut.
3. Put the refrigerant cylinder upside down on the electronic scale. Clear the reading on the balance.

   If the R410A refrigerant is provided by Huawei, put the refrigerant steel vessel upside down when charging in the refrigerant. If the refrigerant is not provided by Huawei, check with the refrigerant provider whether the steel vessel has a siphon. If the vessel has a siphon, do not put it upside down when charging refrigerant. If the vessel has no siphon, put it upside down when charging refrigerant. These measures ensure that the refrigerant is charged in the liquid form.

4. Open the pressure gauge valves and refrigerant cylinder valve shown in Figure 6-4 to charge refrigerant.
   • Do not move the pipe or steel vessel when charging refrigerant. Otherwise, the value on the electronic scale is influenced.
   • When filling refrigerant for a cooling system without a low temperature component, open only the low-pressure valve. Precharge 1 kg of refrigerant from the low pressure side, and then close the low-pressure valve. After that, open the high-pressure valve and charge the remaining refrigerant from the discharge pipe needle valve.
   • When filling refrigerant for a cooling system with a low temperature component, open only the low-pressure valves of pressure gauges 1 and 2. Precharge 1 kg of refrigerant from the low pressure valve, and then close the low-pressure valve of pressure gauge 1. Then, open the high-pressure valves of pressure gauges 1 and 2 and charge the remaining refrigerant from the discharge charge pipe needle valve and liquid pipe needle valve.

5. The amount of refrigerant precharged must be more than half of the total charge amount calculated and less than the total charge amount. If refrigerant is not charged to the total amount in the precharging process, charge the remaining amount of refrigerant during power-on commissioning. For details about commissioning, see Charging the Remaining Refrigerant.
6. After the refrigerant is charged, close all pressure gauge valves and the refrigerant cylinder valve.

   Tighten the needle valve bonnets when the charge is complete. Check whether a needle valve leaks by applying soap bubbles to the valve vent or using a halogen leak detector. If the valve leaks, contact Huawei technical support.