Panasonic CS-TZ50TKEW / CU-TZ50TKE Service Manual ▷ View online
53
13.7 Repairing of refrigerant cycle / Brazing point
13.7.1 Preparation for repairing of refrigerant cycle / brazing
Brazing which is a technique needed for repairing refrigerant cycle requires advanced technique and experience, and
this brazing procedure can only be performed by the workers who completed “Gas Welding Skill Training” regulated
by the Occupational Safety and Health Act, and went through the training programs of refrigerant operations.
Dismantling and re-connecting (assembling) refrigerant system requires working space, and the space has to ensure
good air flow and fire prevention (water bucket and fire extinguisher). Moreover, the worker has to ensure the
wearing of goggles, grabs, safety shoes, and long sleeve shirts, and be aware of work safety and attempt to prevent
secondary defect (quality assurance of products). For brazing the indoor / outdoor unit structural components (heat
exchangers, compressors, expansion valves, four-way valve blocks), after the recovery of all refrigerant, confirm that
no refrigerant remains in the system, and fully open the 2-way and 3-way valves. When the brazing is conducted
outside, check and make sure no refrigerant is contained in the air (be careful with vaporized refrigerant).
Furthermore, protect the compressor terminal with metal plates, and heat but use wet clothes to cool down (releasing
the heat) the expansion valves, and four way valves (prevent destruction of parts). In brazing, it is important to pour
the brazing material without melting the base metal based on capillary action principle. In case of holes and oxidizing
caused by overheating, do not perform re-brazing or alteration but replace the parts.
this brazing procedure can only be performed by the workers who completed “Gas Welding Skill Training” regulated
by the Occupational Safety and Health Act, and went through the training programs of refrigerant operations.
Dismantling and re-connecting (assembling) refrigerant system requires working space, and the space has to ensure
good air flow and fire prevention (water bucket and fire extinguisher). Moreover, the worker has to ensure the
wearing of goggles, grabs, safety shoes, and long sleeve shirts, and be aware of work safety and attempt to prevent
secondary defect (quality assurance of products). For brazing the indoor / outdoor unit structural components (heat
exchangers, compressors, expansion valves, four-way valve blocks), after the recovery of all refrigerant, confirm that
no refrigerant remains in the system, and fully open the 2-way and 3-way valves. When the brazing is conducted
outside, check and make sure no refrigerant is contained in the air (be careful with vaporized refrigerant).
Furthermore, protect the compressor terminal with metal plates, and heat but use wet clothes to cool down (releasing
the heat) the expansion valves, and four way valves (prevent destruction of parts). In brazing, it is important to pour
the brazing material without melting the base metal based on capillary action principle. In case of holes and oxidizing
caused by overheating, do not perform re-brazing or alteration but replace the parts.
13.7.2 Adjustment
of vacuum pump pressure
1. Cylinder with adjustment handle
1. Check and confirm the adjustment handle of the 1
st
pressure adjuster is loosen (anticlockwise). If cylinder
valve is opened when the 1
st
gauge pressure adjust handle is closed, the 2
nd
gauge might get broken.
The primary gauge
(High pressure)
The secondary gauge
(Low pressure)
The secondary gauge
(Low pressure)
Adjustment
handle
Adjustment
handle
Oxygen regulator
Propane regulator
Main valve
Main valve
2. Open the cylinder valve, and check the remaining amount with the first t side pressure gauge.
3. Check the pressure of 2
3. Check the pressure of 2
nd
gauge and turn the adjustment handle to clock-wise direction to adjust the
pressure.
◎
◎
Oxygen 2
nd
side gauge pressure・・・・・・・・・・0.5 MPa (5.0 kgf / cm
2
)
◎
Propane 2
nd
side gauge pressure・・・・・・・0.05 MPa (0.5 kgf / cm
2
)
54
2. Cylinder without adjustment valve
2
nd
side gauge pressure is adjusted by the adjuster.
Check the both side valves of the torch and open the cylinder valve to check the remaining refrigerant in the
cylinder.
Caution: Do not attach oil component on the connection port of the adjuster.
Especially, use an oxygen cylinder adjuster which is no oil substance type. Do not dismantle or repair the
adjuster and pressure gauge.
cylinder.
Caution: Do not attach oil component on the connection port of the adjuster.
Especially, use an oxygen cylinder adjuster which is no oil substance type. Do not dismantle or repair the
adjuster and pressure gauge.
Propane tank
(Gray)
Oxygen tank
(Black)
Black hose
Orange hose
Regulator
Regulator
Main valve
Main valve
Fuel gauge
0~25 MPa
(0~250 k
gf / cm²)
Fuel gauge
0~3 MPa
(0~30 k
gf / cm²)
13.7.3 Checking of gas provision
Checking there is no fire around the torch, and then confirm the provision of gas.
1. Slightly open the “propane valve” of the torch, and make sure the gas comes out from the torch crater and then
1. Slightly open the “propane valve” of the torch, and make sure the gas comes out from the torch crater and then
close the “propane valve”.
2. Slightly open the “oxygen valve” of the torch and make sure the gas comes out from the torch crater and then
close the “oxygen valve”.
Check there is no gas leakage around the hose connection.
Check there is no gas leakage around the hose connection.
13.7.4 Adjustment
of
flame
1. Slightly open the “propane valve” of the torch and lit with spark lighter.
This moment, the flame is only by propane and the color is red.
2. Gradually open the “oxygen valve” of the torch to mix oxygen, and adjust the amount of propane and oxygen with
the valve to make the flame suitable for brazing work.
If the white core flame splits into two, the torch crater might be clogged. In this case, remove the crater from the
torch and check.
If the white core flame splits into two, the torch crater might be clogged. In this case, remove the crater from the
torch and check.
Oxygen (Black hose)
Propane (Orange hose)
Propane valve
Oxygen valve
Nozzle
55
13.7.5 Types of flame
Types of flame change based on the proportion of propane and oxygen.
[Neutral Flame]
Perform brazing with this flame
(This is a flame when oxygen and propane are mixed at proper proportion, and has lesser effect on the brazed
metals)
[Neutral Flame]
Perform brazing with this flame
(This is a flame when oxygen and propane are mixed at proper proportion, and has lesser effect on the brazed
metals)
White core flame
10 ~ 15 mm
Outer flame (Light orange color)
[Carbide Flame]
When propane is excessive, the flame has white color flame in between the white core flame and outer flame.
(This is due to the lack of oxygen and the proportion of unburned propane is excessive.
The black carbon created during the brazing work may contaminate the surface of the brazed metal).
When propane is excessive, the flame has white color flame in between the white core flame and outer flame.
(This is due to the lack of oxygen and the proportion of unburned propane is excessive.
The black carbon created during the brazing work may contaminate the surface of the brazed metal).
White core flame
Pale white
Outer flame (Blue color)
[Oxidizing Flame]
Oxygen is more compared to the neutral flame. Although the flame size is small, this has the highest flame heat.
However, due to the excessive oxygen contained in the flame, the brazing point gets oxidized. (This flame may cause
holes, due to the high heat. The pipe may get melt）
Oxygen is more compared to the neutral flame. Although the flame size is small, this has the highest flame heat.
However, due to the excessive oxygen contained in the flame, the brazing point gets oxidized. (This flame may cause
holes, due to the high heat. The pipe may get melt）
White core flame
Outer flame (Blue orange color)
13.7.6 Closing the flame
[In case of short break]
1. Close the “propane valve” of the torch.
2. Close the “oxygen valve” of the torch.
[In case of finishing work]
1. As above, close the flame following the procedure of “In case of short break”.
2. Completely close the valves of oxygen and propane cylinders.
3. Release the remaining gas inside the hose by opening the “oxygen valve” and “propane valve” of the torch.
Confirm the 1
1. Close the “propane valve” of the torch.
2. Close the “oxygen valve” of the torch.
[In case of finishing work]
1. As above, close the flame following the procedure of “In case of short break”.
2. Completely close the valves of oxygen and propane cylinders.
3. Release the remaining gas inside the hose by opening the “oxygen valve” and “propane valve” of the torch.
Confirm the 1
st
and 2
nd
side gauge pressures of “oxygen” and “propane” cylinder pressure adopter are “zero”.
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13.7.7 Selection
of
brazing material
Use BAg brazing material (silver solder) to increase the welding performance.
Category
JIS
Standard
Number
Composition of ingredients (%)
Temperature (°C)
Tensile strength
(Reference)
Characteristics
and
applications
Ag
Cu Zu Cd Ni P
Solidus Liquidus
Brazing
temp
Kgf•cm
2
Base
material
BAg
BAg •
1A
49.0
~
51.0
14.5
~
16.5
14.5
~
18.5
17.0
~
19.0
—
—
approx.
625
approx.
635
635
~
760
45.5
S20C
Liquidity is good at
low temperature,
it is preferable to
it is preferable to
a small junction of
the gap in the
universal form.
BAg •
1
44.0
~
56.0
14.0
~
16.0
14.0
~
18.0
23.0
~
25.0
—
—
approx.
605
approx.
620
620
~
760
45.5 S20C
It has similar
performance to the
BAg •
1A, and
suitable for every
base material
except the light
weight metal.
BAg •
2
34.0
~
36.0
25.0
~
27.0
19.0
~
23.0
17.0
~
19.0
—
—
approx.
605
approx.
700
700
~
845
45.5 S20C
It is a brazing
filler metal in
universal form,
suitable for a
slightly larger gap
junction.
BAg •
3
48.0
~
51.0
14.5
~
16.5
13.5
~
17.5
15.0
~
17.0
2.5
~
3.5
—
approx.
630
approx.
690
690
~
815
35
~
70
SS
~
SUS
It has good
corrosion
resistance in
stainless
steel-based
brazing, suitable for
brazing tungsten
carbide, aluminum
bronze and copper.
BCuP
BCuP-2
—
remain
—
—
—
6.8
~
7.5
approx.
710
approx.
785
690
~
815
21
~
24.5
Cu
Good liquidity,
suitable for brazing
copper tube.
BCuP-3
4.8
~
5.2
remain
—
—
—
5.8
~
6.7
approx.
645
approx.
815
720
~
815
21
~
24.5
Cu
Suitable for brazing
when the joint
spacing is not
spacing is not
constant
BCuP-5
14.5
~
15.5
remain
—
—
—
4.8
~
5.3
approx.
645
approx.
800
705
~
815
21
~
24.5
Cu
When brazing of
copper and copper,
it is used without a
flux, but not
possible for brazing
basic materials
Caution
BCuP (phosphorus copper wax) is easy to react with sulfur, and makes a brittle compound water soluble, and causes
gas leakage. In hot spring areas, use other brazing materials or paint the surface for protection.
13.7.8 Need of flux
Use flux to protect the base materials.
1. Remove impurity and oxide film on the metal base, and improve the flow of the brazing material.
2. Prevent oxidation of the metal surface in brazing.
3. Reduce the surface tension of the brazing material.
1. Remove impurity and oxide film on the metal base, and improve the flow of the brazing material.
2. Prevent oxidation of the metal surface in brazing.
3. Reduce the surface tension of the brazing material.
13.7.9 Need of nitrogen gas
In order to prevent oxidation in the pipe, perform the brazing operation in nitrogen gas flow.
Flow rate 0.05 m
Flow rate 0.05 m
3
/ h, or pressure reducing valve at 0.02 MPa (0.2kgf / cm
2
) below.
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