20
5. HOW TO PROCESS TUBING
Both the liquid tubing and the gas tubing sides are connected
by a flare nut.
5-1. Connecting the Refrigerant Tubing
Use of the Flaring Method
Many of conventional split system air conditioners employ the
flaring method to connect refrigerant tubes which run between
indoor and outdoor units. In this method, the copper tubes are
flared at each end and connected with flare nuts.
Flaring Procedure with a Flare Tool
(1) Cut the copper tube to the required length with a tube
cutter. It is recommended to cut approx. 30 – 50 cm longer
than the tubing length you estimate.
(2) Remove burrs at the end of the copper tube with a tube
reamer or file. This process is important and should be
done carefully to make a good flare. (Fig. 5-1)
NOTE
When reaming, hold the tube end downward and be sure that
no copper scraps fall into the tube. (Fig. 5-2)
(3) Remove the flare nut from the unit and be sure to mount it
on the copper tube.
(4) Make a flare at the end of the copper tube with a flare tool.
(Fig. 5-3)
NOTE
A good flare should have the following characteristics:
● inside surface is glossy and smooth
● edge is smooth
● tapered sides are of uniform length
Deburring
Before After
Copper
tubing
Reamer
Fig. 5-1 Fig. 5-2
Flare nut
Copper
tubing
Flare tool
Fig. 5-3
Caution Before Connecting Tubes Tightly
(1) Apply a sealing cap or water-proof tape to prevent dust or
water from entering the tubes before they are used.
(2) Be sure to apply refrigerant lubricant to the matching
surfaces of the flare and union before connecting them
together. This is effective for reducing gas leaks. (Fig. 5-4)
Fig. 5-4
(3) For proper connection, align the union tube and flare tube
straight with each other, then screw in the flare nut lightly
at first to obtain a smooth match. (Fig. 5-5)
Fig. 5-5
● Adjust the shape of the liquid tube using a tube bender at the
installation site and connect it to the liquid tubing side valve
using a flare.
Cautions During Brazing
● Replace air inside the tube with nitrogen gas to prevent
copper oxide film from forming during the brazing
process. (Oxygen, carbon dioxide and Freon are not
acceptable.)
● Do not allow the tubing to get too hot during brazing.
The nitrogen gas inside the tubing may overheat,
causing refrigerant system valves to become damaged.
Therefore allow the tubing to cool when brazing.
● Use a reducing valve for the nitrogen cylinder.
● Do not use agents intended to prevent the formation
of oxide film. These agents adversely affect the
refrigerant and refrigerant oil, and may cause damage or
malfunctions.
Apply refrigerant lubricant.
Union
Flare nut
MiniVRFeng.indd20MiniVRFeng.indd20 2011/08/2613:45:202011/08/2613:45:20
www.ampair.co.uk | sales@ampair.co.uk
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