F. Leak detection method
For systems containing
fl
ammable refrigerants
,
the following methods for detecting leaks are
acceptable
:
Electronic leak detectors can be used for the detection of
fl
ammable refrigerants
,
but the
sensitivity may not be su
ffi
cient or may require recalibration
(the instrument calibration
should be performed in a refrigerant-free environment) to ensure that the leak detector does
not become a potential ignition source
,
and applies to the measured refrigerant
,
th
e leak
detector should be set to the lowest
fl
ammable concentration of the refrigerant
(in percent)
,
calibrated with the used refrigerant and adjusted to the appropriate gas concentration test
range
(max.25%).
The leak detection
fl
uid is suitable for most refrigerants
,
but do not use oxygenated solvents
to prevent oxygen and refrigerant from reacting and corroding the copper pipeline.
If leakage is suspected
,
all open
flames should be r
emoved from the site or extinguished.
If a leak occurs where welding is required
,
all refrigerant should be recovered
,
or the refrigerant
should be completely isolated away from the leak
(using shut-o
ff
valves). Before welding and
during welding
,
use oxygen-free. Nitrogen
(OFN) puri
fi
es the entire system.
G. Remove and vacuum
When performing maintenance or other operations on the refrigeration circuit
,
routine
procedures should be followed
,
but the
flammability of the r
efrigerant should also be
considered.
Follow these procedures
:
-Clear refrigerant
-Purge the line with inert gas
-Vacuum
-
P
urge the pipe again with inert gas
-
C
utting pipelines or welding
Refrigerant should be recycled to a suitable storage tank. The system should be purged with
oxygen-free nitrogen to ensure safety. This process may need to be repeated several times.
This operation must not be performed with compressed air or oxygen.
In the purging process
,
the system is
fi
lled with oxygen-free nitrogen to reach the working
pressure under the vacuum state
,
and then the oxygen-free nitrogen is discharged to the
atmosphere. Finally
,
the system is evacuated to a vacuum
,
and the process is repeated until
the refrigerant in the system is completely removed. After the last charge of anaerobic nitrogen
,
the gas is released to atmospheric pressure and the system can then be welded.
Such as pipe
welding operations
,
the above operation is very necessary.
Make sure there are no ignition sources near the outlet of the vacuum pump and that it is well
ventilated.
H. Charge the refrigerant program
As a supplement to regular procedures
,
add the following requirements
:
-Ensure that when using the refrigerant charging equipment
,
no inter-contamination between
di
ff
erent refrigerants will occur
,
and the piping for charging the refrigerant should be as short as
possible to reduce the residual amount of refrigerant therein.
-Tanks should be kept vertically upward
-Ensure that the cooling system has been grounded before
fi
lling the refrigerant
-Label the system after
fi
lling
(or when it has not been completed)
-Must pay attention not to overcharge
The pressure test was performed with oxygen-free nitrogen before recharging the system.
After the
fi
llng was completed
,
a
leak test was performed before the test operation. A leak test
should be conducted when leaving the area.
19
Summary of Contents for MDB-16150HIW
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