Refrigerant Piping Work - Mitsubishi Heavy Industries SRK25ZJ-S Technical Manual

2. REFRIGERANT PIPING WORK

1) Restrictions on unit installation and use
Check the following points in light of the indoor unit specifications and the installation site.
Observe the following restrictions on unit installation and use. Improper installation can result in a compressor failure or performance degradation.
Additional refrigerant charge is not required at all.
Restrictions
Main pipe length
When the outdoor unit is positioned higher,
Elevation difference between
indoor and outdoor units
When the outdoor unit is positioned lower,
The use restrictions appearing in the table above are applicable to the standard pipe size combinations shown in the table below.
CAUTION
2) Determination of pipe size
Determine refrigerant pipe size pursuant to the following guidelines based on the
indoor unit specifications.
Outdoor unit connected
Refrigerant piping (branch pipeL)
Indoor unit connected
3) Refrigerant pipe wall thickness and material
Select refrigerant pipes of the table shown on the right wall thickness and
material as specified for each pipe size.
Select pipes having a wall thickness larger than the specified
NOTE
minimum pipe thickness.
4) On-site piping work
Take care so that installed pipes may not touch components within a unit.
IMPORTANT
If touching with an internal component, it will generate abnormal sounds and/or vibrations.
How to remove the side cover
Please remove the screw of a side cover and remove to the front.
Carry out the on site piping work with the operation valve fully closed.
Give sufficient protection to a pipe end (compressed and blazed, or with an adhesive tape) so
that water or foreign matters may not enter the piping.
Bend a pipe to a radius as large as practical.(R100 R150) Do not bend a pipe repeatedly to correct
its form.
Flare connection is used between the unit and refrigerant pipe. Flare a pipe after engaging a
flare nut onto it. Flare dimensions for R410A are different from those for conventional R407C.
Although we recommend the use of flaring tools designed specifically for R410A, conventional
flaring tools can also be used by adjusting the measurement of protrusion B with a protrusion
control gauge.
Tighten a flare joint securely.
Dimensional restrictions Marks appearing in the drawing on the right
15m or less
10m or less
10m or less
When pipe is brazing.
Model 20, 25, 35
G s a i p e p Liquid pipe
9.52 6.35
Flare Flare
9.52 6.35
9.52 6.35
Pipe diameter [mm]
Minimum pipe wall thickness [mm]
Pipe material*
*Phosphorus deoxidized seamless copper pipe ICS 23.040.15, ICS 77.150.30
L
H
H
About brazing
Brazing must be performed under a nitrogen gas flow.
Without nitrogen gas, a large quantity of foreign matters (oxidized film) are created,
causing a critical failure from capillary tube or expansion valve clogging.
Plug the end of the pipe with tape, or other
Station valve
material, and fill the pipe with nitrogen gas.
N
Taping
2
Only use nitrogen gas (N )
2 Brazing
6.35 9.52
0.8 0.8
O-type pipe O-type pipe
Screw
Side cover
H
Outdoor unit
Primary side Secondary side
0.5MPa
Hand
Nitrogen
Relief valve
gas
A
Flared pipe end : A
(mm)
Copper
0
pipe outer
0 4
diameter
6.35 9 1
9.52 13.2
Copper pipe protrusion for flaring : B
Copper
In the case of a rigid (clutch) type
pipe outer
With an R410A tool With a conventional tool
diameter
6.35
0 0.5
9.52
Indoor unit
L
(mm)
1.0 1.5