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Dc Inverter VRF plus Water Heater Solution Service Manual INSTALLATION

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After a section of pipeline is welded, cleaning of piping is necessary.

Nitrogen pressure is utilized to remove foreign matters (such as dust, water and beryllium oxide

caused by welding) in the piping.

1）Main purposes of cleaning are as follows：

 To eliminate oxide caused by insufficiency of nitrogen-filled protection during pipe welding.

 To remove foreign substances and water that may enter the piping due to improper

storage and transport.

 To check whether big leakage is existent at connections of the piping between indoor unit

and outdoor unit

2）Cleaning steps：

a. Mount a pressure gauge on nitrogen cylinder;

b. High pressure end of the pressure gauge is connected to the refrigerant filling nozzle of the

small pipe (liquid pipe)

c. All copper pipe ports outside the A side of indoor unit shall be blocked by blanking plugs.

d. The valve on nitrogen cylinder shall be opened to maintain pressure at 28Kgf/ cm

e. Check whether nitrogen flows through the liquid pipe of indoor unit A

f. Cleaning

The mouth of the pipe shall be blocked with insulation material held by hand until pressure rises to

a level difficult to be withstood, and at the moment the insulation material shall be released quickly.

And then the mouth shall be blocked again. Repeat such procedures several times. Afterwards,

use a wood board posted with white paper to check it. If there is not evident dirt on the white paper,

the pipe will be considered clean.

g. Shut off the main valve of nitrogen

h. Repeat the above procedures on indoor unit B

i. After cleaning of liquid pipe, gas pipe shall be cleaned in the same way.

10.9 Pressure Maintaining and Leak Hunting

1）Pressure maintaining of refrigerant piping

After refrigerant piping of a system is welded

 A refrigerant filling nozzle shall be welded respectively on the big pipe and on the small pipe

on the outdoor unit side.

 Pipes connected to the end of indoor unit and outdoor unit shall be clamped to be flat and

welded to be sealed.

Steps of pressure maintaining and leak hunting of refrigerant piping are as follows: