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6-2. Refrigerant piping installation
6-2-1. Piping materials and joints used
For the refrigerant piping installation, copper pipes and joints are mainly used.
Copper pipes and joints suitable for the refrigerant must be chosen and installed.
Furthermore, it is necessary to use clean copper pipes and joints whose interior surfaces are less affected by
contaminants.
(1) Copper pipes
It is necessary to use seamless copper pipes which are made of either copper or copper alloy and it is desirable
that the amount of residual oil is less than 40 mg / 10 m.
Do not use copper pipes having a collapsed, deformed or discolored portion (especially on the interior surface).
Otherwise, the expansion valve or capillary tube may become blocked with contaminants.
As an Air to Water Heat Pump using R32 incurs pressure higher than when using R22, it is necessary to choose
adequate materials.
Thicknesses of copper pipes used with R32 are as shown in Table 6-2-1. Never use copper pipes thinner than 0.8
mm even when it is available on the market.
Refer to the ā6-6. Instructions for re-use piping of R22 or R407Cā.
Table 6-2-1 Thicknesses of annealed copper pipes
(2) Joints
For copper pipes, flare joints or socket joints are used. Prior to use, be sure to remove all contaminants.
a)Flare joints
Flare joints used to connect the copper pipes cannot be used for piping whose outer diameter exceeds 20 mm. In such a case,
socket joints can be used.
Sizes of flare pipe ends, flare joint ends and flare nuts are as shown in Tables 6-2-3 to 6-2-5 below.
b) Socket joints
Socket joints are such that they are brazed for connections, and used mainly for thick piping whose diameter is larger than 20 mm.
Thicknesses of socket joints are as shown in Table 6-2-2.
Table 6-2-2 Minimum thicknesses of socket joints
Wall thickness (mm)
Nominal diameter Outer diameter (mm) R410A or R32 R22
1/4 6.4 0.80 0.80
1/2 12.7 0.80 0.80
5/8 15.9 1.00 1.00
Nominal diameter
Reference outer diameter of
copper pipe jointed (mm)
Minimum joint thickness
(mm)
1/4 6.4 0.50
1/2 12.7 0.70
5/8 15.9 0.80
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