Specifications
(1) Brazing work requires a high level of technology and
experience. The work must be carried out by a worker
who has completed the “Gas Welding Skill Seminar”
specified under the Labor and Sanitation Laws, following
theoretical knowledge.
(2) Brazing work must be carried out while flowing dry
nitrogen gas (N2) so that an oxidized layer does not form
on the inside of the piping material.
(3) Work methods to prevent oxidization.
1. Install a pressure-reducing valve and flow meter on the
nitrogen cylinder.
2. Use a 6.35 mm copper pipe for the pipe led to
the piping material, and install it on the flow meter of the
cylinder side.
After completing all piping connections, always carry out
a tightness test for the reffrigerant piping, and confirm
that there is no gas leakage.
Note) For pipes having valves that open with the
continuity of a solenoid valve, etc., carry out the
leakage test, vacuuming and gas charge in the
continuity state.
(1) Tightness leakage test procedures
Always observe the "maker indicated value" for the
"applicable gas type", "high pressure side", "low pressure
side", and "pressurizing time".
Cautions
(1) Confirm that there are no scratches or dirt, etc., on
the flare and union section.
(2) When applying lubrication oil on the inside and
outside of the flare, always use the same lubrication oil
as that used in the installed air conditioner. Use of
different oil will cause the lubrication oil to deteriorate
and the compressor to burn, etc.
(1) Vacuum pump
Select an adequate vacuum pump considering the
workability and ease of use, etc. Use the capacity of the
refrigerant cycle configuring the target device as a
guideline. Fitting screw specifications: Use UNF7/16 for
the R407C fitting.
(2) Gauge manifold
Use gauge manifolds and charge hoses dedicated for the
HFC–based refrigerant. If tools used with HFCF22
R407C Refrigerant Charging Method
Copper pipe
Connection section (A)
Connection section (B)
Installation of
gas charge device
Completion
of vacuuming
Tightness check
Start of
vacuuming
Charge of small
amount of refrigerant
Gas leakage test
Charge of specified
amount of refrigerant
Tightening of piping
connection sections
10 to 154 min.,
7500 mmHg or more
Installed gauge's
needle must not
rise for 5 min.
Basic work flow
Flare nut
Spanner
Stop valve
Flow meter
6.35 pipe
Piping
Rubber plug
Nitrogen gas
From nitrogen cylinder
Torque wrench
Half union
Flare nut
Oil application (ease the nut friction)
Oil application (improve the
seal face sealing)
Apply the lubrication oil on the inside of the flare and
on the outer surface of the union.
Always tighten the connection section with the correct installation torque.
Nitrogen gas
*Invert and charge or use a refrigerant cylinder with syphon pipe.
16
Male side
Female side
1. Restrictions for charging refrigerant to system and charge cylinder from refrigerant cylinder.
Refrigerants that have restrictions in respect to the liquid-phase charging may change in composition at the gaseous-
phase, may not achieve the specified performance, or may damage device. Always charge liquid-phase refrigerant.
2. Liquid-phase charging methods and cautions
(1) The conventional CHFC22 is a singlerefrigerant, and there were no limits to the refrigerant state during charging.
Thus, when charging the refrigerant into the system, the following procedure is the most common.
When charging the refrigerant from the intake side, the refrigerant had to be charged in the gaseous state to prevent liquid return operation at the compressor.
(2) With the HFC refrigerant, the composition changes if
not in a liquid-phase, and thus, liquid-phase charging
is required. However, in terms of protecting the
compressor, the refrigerant at the intake side of the
system must still be in a gaseous-phase. The methods
for charging the refrigerant into the system basically
do not differ from the procedures given above. Thus,
when charging HFC refrigerant requiring liquid-phase
M
3. Always seal (using rubber plug, etc.) the gap between
the piping material and nitrogen conduit to prevent the
backflow of nitrogen gas.
4. When flowing the nitrogen gas, do not stop it at the end
of the piping side. Instead, leave this side open.
5. The guideline for the nitrogen gas is 0.05m/h or
0.02MPa(0.2kg/cm2) or less with the pressure-reducing
valve.
6. After working, flow the nitrogen gas until the piping
cools down (to a point where the pipe can be touched by
hand).
7. Remove all flux after brazing work.
(2)Cautions
1. After welding, if pressure is applied before the piping
temperature drops, the pressure will drop after the pipe
cools.
2. The pressure will rise and drop according to the
outdoor temperature. (The constant container gas is
proportional to the absolute temperature. )
*Absolute pressure at measurement = absolute pressure at
pressurizing (273C + temperature at pressurizing/273C+
temperature at measurement)
(3) Locating a leak and its repair
1. If there is a leak, use soap water, etc., to find and
repair the leakage section in the welding sections, flare
section, flange section and each unit section. (Always
flow nitrogen when carrying out repairs that require
welding.)
2. If the leakage place is difficult to find, mix Freon
gas, and find the approximate leakage place with a leak
tester, etc.
3. Always carry out the leakage test before embedding
piping recessed in pits, etc.
charging into the system, the compressor must be run,
and caution is required when charging from the
suction side.Even when charging the refrigerant from
the suction side, always draw out the refrigerant from
the cylinder or charge cylinder in a liquid state.
Actual methods are as follow:
*1. Close the refrigerant by operating the adjustment
valve on the gas cylinder, and when it is drawn into
the system, adjust so that refrigerant is gassified.
*2. There is a dedicated tool for converting the liquid
refrigerant into a mist. This tool is installed on the
cylinder or charge cylinder valve and used.
2. Flare connection
3. Brazing work
4. Tightness test
5. Vacuuming
refrigerant are used, the device could be damaged by
deteriorated lubrication oil (mineral oil) that is
incompatible.
Charge the refrigerant in the liquid state from the service port (high pressure side ) of the liquid outlet operation valve > run the compressor,
charge the insufficient amount from the service port (low pressure side) of the intake operation valve in the gaseous state.
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