Hantech A020BA-Serie Bedienungsanleitungen Seite 17

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 overfill the refrigeration system.
Prior to recharging the system it shall be pressure tested with OFN. The system shall be leak
tested on completion of charging but prior to commissioning. A follow up leak test shall be carried
out prior to leaving the site.