Heat Preservation Of Refrigerant Piping - Gree DC Inverter Multi VRF Service Manual

DC INVERTER MULTI VRF
Steps:
Nitrogen is charged to reach 4.15MPa and remains at the pressure for 24h (nitrogen shall be
filled from refrigerant filling nozzles at the big valve as well as the small valve using a pressure
gauge; during pressure maintaining after nitrogen is charged, the pressure gauge shall not be
dismantled.)
2 Observe whether pressure changes in 24 hours. (for eligibility criteria, see pressure
maintaining and leak hunting of refrigerant piping in 5.5.2)
If any leakage, please check threaded connections and new welded spots of indoor unit and
outdoor unit. Repair welding shall be performed immediately. Afterwards, pressure maintaining is
repeated until eligibility is reached.
2 Cautions:
a.
The range of pressure gauge for R410A system test shall be over 4.5Mpa
b.
At the same time, record the readings on pressure gauge, ambient temperature and test time;
c.
Pressure correction: The pressure will change by 0.01Mpa with temperature changing by every 1
d.
It is only acceptable when the pressure is kept unchanged;
e.
To keep the pressure for a long time, the pressure shall be decreased to 0.5MPa or lower. High pressure of a
long time might cause leakage at the weld and result in safety risk.
f.
Before completing the airtight test of refrigerant pipe, never carry out thermal insulation or wrapping work at the
weld and flared connection of indoor unit. The pressure shall be simultaneously applied from the pipes on outdoor
side. Never apply pressure from a single side
1.4
Caution: Before completing the airtight test of refrigerant pipe, never carry out thermal insulation or wrapping

6.10 Heat Preservation of Refrigerant Piping

1 Connection of thermal insulation pipe
Carry out thermal insulation to the refrigerant pipe after confirming that it has no leakage.
Please perform thermal insulation to the refrigerant pipe according to the steps below
Check if the thermal insulation pipe has met the thickness requirements. If not, the condensing
water is easy to attach on thermal insulation pipe and finally drips. The thickness requirements are
shown below:
Refrigerant Pipe (mm) (Outer Dia. x Thickness)
Wrap the refrigerant pipe according to required thickness. The clearance between thermal
insulation pipes shall be sealed with self-adhesive sticker.
Wrap the t hermal insulation pipes with tapes, thus to extend their ageing time.
2 Cautions:
The thermal insulation materials shall be able to withstand the pipe temperature. For heat pump
work at any weld.
Φ6.35×0.5
Φ9.52×0.71
Φ12.7×1
Φ15.9×1
Φ19.05×1
Φ22.2×1.5
Φ25.4×1.5
Φ28.6×1.5
Φ34.9×1.5
Apply pressure
simultaneously from gas
pipe and liquid pipe
Thickness of Thermal Insulation
Materials (mm)
≥10
≥10
≥15
≥15
≥15
≥20
≥20
≥20
≥20
INSTALLATION
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