Welding Indoor Unit Pipes

Precautions

Exhausting Nitrogen

1. Remove the bonnet of the low-pressure needle valve and connect the pressure gauge leather hose to the needle valve.
   Figure 4-61 Exhausting nitrogen
   

   (1) Low-pressure needle valve

   (2) Discharge pipe needle valve

   (3) Liquid pipe needle valve

2. Open the pressure gauge valve. Loud noises of air flow are generated at first and then disappear gradually.
3. After the airflow noise disappears, remove the rubber hose and install the valve bonnet.
4. Continue exhausting nitrogen from the discharge pipe needle valve and liquid pipe needle valve by performing Step 1 to Step 3.

Bottom Pipe Routing

1. Use a welding torch to remove the plug at the lower end of the refrigerant pipe.
   Figure 4-62 Bottom pipe routing
   

   (1) Gas pipe

   (2) Liquid pipe

   • Be careful during welding to avoid burning components, such as rubber rings, inside the cabinet.
   • Use a rubber hose to connect the nitrogen cylinder which connecting the reducing valve and the end of the copper pipe, then fill nitrogen at 0.03–0.05 MPa into the copper pipe to avoid internal oxidation, as shown in Figure 4-63.
   • When welding a gas pipe, gently inject nitrogen into the pipe through the discharge pipe needle valve.
   • When welding a liquid pipe, gently inject nitrogen into the pipe through the liquid pipe needle valve.
   Figure 4-63 Welding pipes
   

2. Cut a cross in the rubber ring using a utility knife and route the pipe wrapped with the thermal insulation foam through the hole.

   Ensure that the rubber ring is not disconnected. If the rubber ring is disconnected or damaged, seal the gaps around the pipes with mastic cement or thermal insulation foam.

3. Connect the gas and liquid pipes to the gas and liquid pipes of the outdoor unit respectively.

Top Pipe Routing

When routing pipes from the top, do not route the pipes over servers or other devices to prevent them from being affected by pipe leakage.

1. Remove the plugs from the top refrigerant pipe using a welding torch.
   Figure 4-64 Top pipe routing
   

   (1) Gas pipe

   (2) Liquid pipe

2. Connect the gas and liquid pipes to the gas and liquid pipes of the outdoor unit respectively. Pipes should be wrapped with thermal insulation foam.