Branch Pipe Installation; Remove Dirt Or Water In The Piping; Airtight Test; Vacuum With Vacuum Pump - Midea VRF V4 Plus I Series Manual

MCAC-VTSM-2014-04

8. Branch pipe installation

The branching pipe must be installed horizontally and error angle of it should not be larger than 10° . Otherwise,
refrigerant assignment will be uneven and malfunction will be caused.

9. Remove dirt or water in the piping

 Make sure there is no any dirt or water in the pipe before connecting the piping to the outdoor units.
 Wash the piping with high pressure nitrogen, never use refrigerant of the outdoor unit to do that.

10. Airtight test

 Connect pipe on hi-pressure side with hi-pressure valve.(For multi-modules parallel connection, please
connect gas balance valves).
 Weld the piping on low-pressure side with gauge joint.
 Charge nitrogen from hi-pressure valve core to gauge joint.
 After airtight test, weld low-pressure ball valve and piping on low-pressure side.
Note:
 The air tightness test is conducted by pressurized nitrogen (R22 system: 28kgf/cm
 It is not allowed to adopt oxide, flammable gas and toxic gas to conduct air tightness test.
 It's not allowable to welding low pressure ball valve with low pressure side piping before charge nitrogen.
 Wrap the lo-valve and the balance valve by wet cloth for protection when welding..

11. Vacuum with vacuum pump

 Do vacuum with vacuum pump instead of refrigerant.
 Vacuuming should be done from liquid and gas side simultaneously. The pressure should be lower than
30Pa.
 Use the vacuum pump which vacuum level lower than -0.1MPa and the air discharge capacity above
40L/min.
 The outdoor unit is not necessary to vacuum, don't open the outdoor unit gas and liquid pipe shut-off valves.
 Make sure the vacuum pump could result as -0.1MPa or below after 2 hours or above operation. If the pump
operated 3 hours or above could not achieve to -0.1MPa or below, please check whether water mix or gas
leak inside of the pipe.
Installation
U-shaped branching pipe
A direction view
Wrong Correct
Horizontal surface
R410A DC Inverter VRF V4 Plus Individual Series 50Hz
A
10°
10°
2
, R410A system: 40kgf/cm
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