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69
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.
70
13.7.10 Checking of brazing (insert) points
1. No impurity on the brazing point
If dirt or oil is attached on the brazing point, the
brazing filler metal does not reach to junction, and
it may cause poor welding.
brazing filler metal does not reach to junction, and
it may cause poor welding.
2. Adequate gap space in the brazing point
The advantage of capillary current situation is
used in brazing. If the gap space is too large, this
phenomenon may not occur and it may cause
poor welding because brazing filler metal does not
flow to join the front part.
used in brazing. If the gap space is too large, this
phenomenon may not occur and it may cause
poor welding because brazing filler metal does not
flow to join the front part.
3. Appropriate size for insertion
The guideline for pipe insertion dimensions is to
three times the diameter of the base material, but
you need to decide the insertion size in
consideration of the clogging of the brazing
material. Generally, for thin pipes, you need to
increase the insert size, and for thick pipe vice
versa.
three times the diameter of the base material, but
you need to decide the insertion size in
consideration of the clogging of the brazing
material. Generally, for thin pipes, you need to
increase the insert size, and for thick pipe vice
versa.
4. Brazing material to flow from top to bottom
Brazing filler metal will easily flow to the
connecting portion by capillary action.
Further, by bending the brazing portion of [dryer
side] of the capillary tube at 15 mm from the tube
top to the angle of about 120°, you can prevent
the damage of dryer inside and the clogging of
brazing material caused by the excessive insertion
of capillary tube.
connecting portion by capillary action.
Further, by bending the brazing portion of [dryer
side] of the capillary tube at 15 mm from the tube
top to the angle of about 120°, you can prevent
the damage of dryer inside and the clogging of
brazing material caused by the excessive insertion
of capillary tube.
Gap 0.025 ~ 0.05 mm
Insert diameter 10 ~ 25 mm
Inner diameter ø6.45
Outer diameter ø6.35
Brazing material
(Runny)
Brazing material
(Hard to flow)
Dryer
15 mm
120°
Filter
(Wire mesh)
Capillary
tube
13.7.11 Brazing and heating
1. Place the flame to a pipe which has more heat
capacity in order to let the brazing material melt by
the pipe heat. Heat the pipe up to the melting
temperature of the brazing material, but when it is
overheating, assess the temperature by pipe color
in order not to melt the pipe.
the pipe heat. Heat the pipe up to the melting
temperature of the brazing material, but when it is
overheating, assess the temperature by pipe color
in order not to melt the pipe.
Burner
Burner
Brazing
material
Brazing
material
The pre-heating is to heat the base material until the melting temperature, and requires certain training to distinguish
the color of the heated base material in order not to melt the material.
The color and temperature of copper tube
Becoming red color • • • • • • • 480°C
Dull red • • • • • • • 650°C
Cherish red • • • • • • • 760°C
Brightening cherish red • • • • • • • 870°C
71
(Reference)
Melting temperature of copper • • • • • • • Approx. 1083°C
Maximum temperature obtained in propane and oxygen • • • • • • • Approx. 1083°C
The important point is to heat the bonding part uniformly within a short period of time until reaching to the brazing
temperature in the following manner.
2. Apply the flame on to the side with better heat transmission. If the pipe thickness is consistent, by heating like
Melting temperature of copper • • • • • • • Approx. 1083°C
Maximum temperature obtained in propane and oxygen • • • • • • • Approx. 1083°C
The important point is to heat the bonding part uniformly within a short period of time until reaching to the brazing
temperature in the following manner.
2. Apply the flame on to the side with better heat transmission. If the pipe thickness is consistent, by heating like
30% iron and 70% copper, the copper pipe inside reaches to brazing temperature.
Iron pipes have low heat transmission and only the part the flame is applied get high temperature, and this
causes oxidization of the pipe. The flow of the brazing filler is affected negatively.
Iron pipes have low heat transmission and only the part the flame is applied get high temperature, and this
causes oxidization of the pipe. The flow of the brazing filler is affected negatively.
3. Apply the flame on to the side of larger heat
capacity.
When brazing a thin tubes such as capillary tube
and dryer, etc., caution has to be taken to apply
the flame to the dryer side (thick pipe side), in
order to prevent burn out by the heat.
When brazing a thin tubes such as capillary tube
and dryer, etc., caution has to be taken to apply
the flame to the dryer side (thick pipe side), in
order to prevent burn out by the heat.
4. When brazing the compressor connection pipes
(suction and discharge), remove the sound
insulation plate and the fan, and place the
compressor stand vertically (to prevent the
leakage of compressor refrigerating machine oil),
and apply the flame from the compressor body
side.
insulation plate and the fan, and place the
compressor stand vertically (to prevent the
leakage of compressor refrigerating machine oil),
and apply the flame from the compressor body
side.
13.7.12 Terminologies of brazing
Pin holes → Small holes are generated on the surface of the brazing metal.
Wet temperature → Liquidus temperature at which the brazing material starts flowing out by heating, generally it is
the liquidus-line temperature.
Blow holes → Hollows made by gas in the brazing material of brazing portion (gas reservoirs).
Pits → As a result of blow holes, small dents generated on the outside surface of welding.
Voids → The blazing material does not reach completely to the brazing part. It cannot be identified from outside.
Wet temperature → Liquidus temperature at which the brazing material starts flowing out by heating, generally it is
the liquidus-line temperature.
Blow holes → Hollows made by gas in the brazing material of brazing portion (gas reservoirs).
Pits → As a result of blow holes, small dents generated on the outside surface of welding.
Voids → The blazing material does not reach completely to the brazing part. It cannot be identified from outside.
72
13.8 <Reference> Analysis method for no error code, no cooling / no
warming
13.8.1 Preparation for appropriate diagnosis
In order to obtain appropriate operation characteristics, minimum 15 minutes or more operation time [testing
operation (rated operation)] is required.
1. Method of rated operation (rated operation)
operation (rated operation)] is required.
1. Method of rated operation (rated operation)
For the models which have two buttons of “emergency operation and forced cooling operation”, press forced
cooling button once. For the models which have only emergency operation button, press the button once for 5
seconds and when hear “beep” sound, release the button. Then, cooling operation starts.
cooling button once. For the models which have only emergency operation button, press the button once for 5
seconds and when hear “beep” sound, release the button. Then, cooling operation starts.
2. Checking the mal-functions of indoor / outdoor units
1) Any obstacles against heat release and air suction? (short circuit)
(Forget to remove the outdoor unit cover or fallen leaves blocking the outdoor unit)
2) Are the indoor unit air filters clean? (obstructing heat suction)
3) Is the setting temperature on the remote controller correct? (is the setting temperature set at lower/higher
3) Is the setting temperature on the remote controller correct? (is the setting temperature set at lower/higher
than the room temperature?)
13.8.2 Understanding and verification of refrigerant cycle
H
eat
exc
han
ge
han
ge
r
H
eat
exc
han
ge
han
ge
r
Compressor
（
COMP）
4-way
valve
Condenser
（
COND）
Expansion
valve
Liquid side
2-way
valve
Gas side
3-way
valve
High temp
High pressure
High pressure
Air
Mid temp /
High pressure
Liquid
Low
temp/
Pressure
liquid
temp/
Pressure
liquid
Low temp
Low pressure
Low pressure
Air
Evaporator
（
EVA）
FM
Fan
Fan
Capillary tube
Indoor unit
Temp difference
Suction temp ＜Cooling＞
８
or more
Release temp ＜Heating＞
１４
or more
＊Measured after 15 mins with strong
fan operation
(Cooling)
Gas pressure
0.9～1.2MPa
Low temp /
Low pressure
Low pressure
Air
Low temp /
Low pressure
Low pressure
liquid
(Cooling
Heating
)
High temp /
High pressure
High pressure
Air
Mid temp /
high pressure
liquid
high pressure
liquid
Low temp /
Low pressure
Liquid
Low pressure
Liquid
Low temp /
Low pressure
Air
Low pressure
Air
Mid temp /
High temp
liquid
(Heating)
Gas pressure
2.2～ 3.0MPa
Release temp
Outdoor temp
Suction temp
Heat exchanger
temp
Heat exchanger
temp
High temp / high
pressure
pressure
Air
「
Indoor
「
」
Outdoor」
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