Hantech 10474165 Bedienungsanleitungen Seite 16

Electronic leak detectors shall be used
to detect flammable refrigerants, but
the sensitivity may not be adequate,
or may need re-calibration. (Detection
equipment shall be calibrated in a
refrigerant-free area.) Ensure that
the detector is not a potential source
of ignition and is suitable for the
refrigerant used. Leak detection
equipment shall be set at a percentage
of the LFL of the refrigerant and
shall be calibrated to the refrigerant
employed and the appropriate
percentage of gas (25 % maximum) is
confirmed.
Leak detection fluids are suitable for
use with most refrigerants but the use
of detergents containing chlorine shall
be avoided as the chlorine may react
with the refrigerant and corrode the
copper pipe-work.
If a leak is suspected, all naked flames
shall be removed/ extinguished.
If a leakage of refrigerant is found
which requires brazing, all of the
refrigerant shall be recovered from
the system, or isolated (by means of
shut off valves) in a part of the system
remote from the leak. Oxygen free
nitrogen (OFN) shall then be purged
through the system both before and
during the brazing process.
7. Removal and evacuation
When breaking into the refrigerant
circuit to make repairs – or for
any other purpose – conventional
procedures shall be used. However,
it is important that best practice
is followed since flammability is a
consideration. The following procedure
shall be adhered to:
— Remove refrigerant;
— Purge the circuit with inert gas;
— Evacuate;
— Purge again with inert gas;
— Open the circuit by cutting or
brazing.
The refrigerant charge shall be
recovered into the correct recovery
cylinders. The system shall be
"flushed" with OFN to render the unit
safe. This process may need to be
repeated several times. Compressed
air or oxygen shall not be used for
this task. Flushing shall be achieved
by breaking the vacuum in the system
with OFN and continuing to fill until
the working pressure is achieved,
then venting to atmosphere, and
finally pulling down to a vacuum.
This process shall be repeated until
no refrigerant is within the system.
When the final OFN charge is used,
the system shall be vented down
to atmospheric pressure to enable
work to take place. This operation is
absolutely vital if brazing operations
on the pipe-work are to take place.
Ensure that the outlet for the vacuum
pump is not close to any ignition
sources and there is ventilation
available.
8. Charging procedures
In addition to conventional
charging procedures, the following
requirements shall be followed.
— Ensure that contamination of
different refrigerants does not
occur when using charging
equipment. Hoses or lines shall be
as short as possible to minimise the
amount of refrigerant contained in
them.
— Cylinders shall be kept upright.
— Ensure that the refrigeration system
is earthed prior to charging the
system with refrigerant.
— Label the system when charging is
complete (if not already).
— Extreme care shall be taken not to
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