LG MULTI F A2UW16GFA0 Engineering Product Data Book page 116

2. Guideline for each installation process
2.2.5 Refrigerant pipe flushing
Flushing is a method of cleaning extraneous matter out of pipes using pressurized gas.
NOTE
Refrigerant pipe flushing of 3 major effects
1. Removal of oxidation bubbles formed inside copper pipes when "nitrogen replacement is insufficient"
during soldering work
2. Removal of extraneous material and moisture from pipes when covering has been insufficient
3. Checks connections in pipes linking outdoor and indoor units (Both liquid and gas pipes)
① Set pressure regulator on nitrogen cylinder.
② Connect the charge hose from pressure regulator to
service port on the liquid pipe side of the outdoor unit
before its connection to B/D unit or indoor unit.
③ Open the main valve on the nitrogen cylinder and set
the pressure regulator to 0.5MPa.
④ Ensure that nitrogen is flowing through the pipe properly.
⑤ For flushing block the end of the pipe with wood insula-
tion block.
⑥ When the pressure becomes great remove the block
quickly.
⑦ Do step 6 & 7 repeatedly till cleanness is ensured.
⑧ Connect the charge hose from pressure regulator to
service port on the gas pipe side of outdoor unit before
its connection to B/D unit or indoor unit.
⑨ Flow the steps 3, 4, 5, 6, 7.
CAUTION
After welding the pipe, nitrogen flushing is strongly
recommended.
13 _ Heat pump
60Hz/R410A
Pressure regulator
Lo Hi
Nitrogen
Primary
side
Secondary
Lo Hi
side 0.5 MPa
Nitrogen
Gas pressure of 0.5 MPa
Wood Insulation
Lo Hi
Taping
Nitrogen