26
ENGLISH
all refrigerant should be recovered, or the refrigerant should be completely
isolated away from the leak (using shut-off valves). Before welding and during
welding, use oxygen-free. Nitrogen (OFN) puri
fi
es the entire system.
15. Removal and evacuation
When performing maintenance or other operations on the refrigeration circuit,
conventional procedures shall be used. However, for
fl
ammable refrigerants it
is important that best practice is followed since
fl
ammability is a consideration.
The following procedure shall be adhered to:
• remove
refrigerant.
•
purge the circuit with inert gas.
• Evacuate
vacuum.
•
purge with inert gas.
•
open the circuit by cutting or brazing.
The refrigerant charge shall be recovered into the correct recovery cylinders.
For appliances containing
fl
ammable refrigerants the system shall be purged
with oxygen-free nitrogen to render the appliance safe for
fl
ammable refriger-
ants. This process may need to be repeated several times. Compressed air or
oxygen shall not be used for purging refrigerant systems.
For appliances containing
fl
ammable refrigerants, refrigerants purging shall be
achieved by breaking the vacuum in the system with oxygen-free nitrogen and
continuing to
fi
ll until the working pressure is achieved, then venting to atmos-
phere, and
fi
nally pulling down to a vacuum. This process shall be repeated
until no refrigerant is within the system. When the
fi
nal oxygen-free nitrogen
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 opera-
tions on the pipe-work are to take place.
Ensure that the outlet for the vacuum pump is not close to any potential ignition
sources and that
ventilation is available.
16. 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
Summary of Contents for Arido SDHM-10L
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