97
GB
DEHUMIDIFIER / AIR PURIFIER
Removal and evacuation
When breaking into the refrigerant circuit to make repairs or for any other
purpose, 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
• Purge again 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 “
fl
ushed”
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 purging refrigerant
systems.
For appliances containing
fl
ammable refrigerants,
fl
ushing shall be achieved
by breaking the vacuum in the system with OFN and continuing to
fi
ll until the
working pressure is achieved, then venting to atmosphere, and
fi
nally pulling
down to a vacuum. This process shall be repeated until no refrigerant is within
the system. When the
fi
nal 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 that ventilation is available.
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
minimize 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 over
fi
ll the refrigeration system.
Prior to recharging the system, it shall be pressure-tested with the appropriate
purging gas. The system shall be leak-tested on completion of charging but