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If a refrigerant leak requiring brazing is found, all refrigerant must be recovered from the system.
Oxygen Free Nitrogen (OFN) must then be purged from the system before and during the brazing
process.
14. Withdrawal and evacuation
When introducing refrigerant into the refrigerant circuit for repair - or for any other purpose -
conventional procedures must be used. However, it is important to follow best practices, as flammability
is a factor to consider. The following procedure must be followed :
Remove refrigerant;
Purge the circuit with an inert gas ;
Evacuate ;
Purge again with an inert gas ;
Opening the circuit by cutting or soldering.
The refrigerant charge must be recovered in the appropriate recovery cylinders. The system must be
"flushed" with DNF to make the unit safe. This process may need to be repeated several times.
Compressed air or oxygen should not be used for this task.
Flushing should be carried out by breaking the vacuum in the system with the FOD and continuing to fill
until the working pressure is reached, then venting to atmosphere, and finally reducing the vacuum. This
process must be repeated until there is no more refrigerant in the system. When the final charge of NFO
is used, the system must be vented to atmospheric pressure to allow the work to proceed.
This operation is absolutely essential to be able to carry out brazing operations on the piping. It must be
ensured that the vacuum pump outlet is not close to a source of ignition and that ventilation is available.
15. Loading procedures
In addition to the standard underwriting procedures, the following requirements must be complied with.
-Make sure that there is no contamination of the different refrigerants when using the charging
equipment. Pipes or lines should be as short as possible to minimize the amount of refrigerant they
contain.
- Cylinders shall be held in an upright position.
- Ensure that the refrigeration system is grounded before charging the system with refrigerant.
- Label the system when loading is complete (if it has not already been done).
- Care must be taken to ensure that the refrigeration system is not overloaded.
Before recharging the system, it must be pressure tested with the NFA. The system must be leak tested
at the end of charging but before commissioning. A follow-up leakage test must be carried out before
leaving the site.
16. Decommissioning
Before performing this procedure, it is essential that the technician is thoroughly familiar with the
equipment and all its details. It is recommended that all refrigerants be recovered safely. Before
performing the task, a sample of oil and refrigerant must be taken in case an analysis is required before
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