INSTRUCTION FOR REPAIRING APPLIANCES CONTAINING R 290
AUTHORISED PERSONS ONLY!
Oxygen free nitrogen (OFN) shall then be purged through the system both before and during the
brazing process.
15. 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 the best practise 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.
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 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 to not overfill the refrigerant 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.
17. Decommissioning
Before carrying out this procedure, it is essential that the technician is completely familiar with the
equipment and all its details. It is recommended good practice that all refrigerants are recovered
safely. Prior to the task being carried out, an oil and refrigerant sample shall be taken in case
analysis is required prior to re-use of reclaimed refrigerant. It is essential that electrical power is
available before the task is commenced.
a) Become familiar with the equipment and its operation.
b) Isolate system electrically.
c) Before attempting the procedure ensure that:
- Mechanical handling equipment is available, if required, for handling refrigerant cylinders;
- All personal protective equipment is available and being used correctly;
- The recovery process is supervised at all time by a competent person.
- Recovery equipment and cylinder confirm to the appropriate standards.
d) Pump down refrigerant system, if possible.
e) If a vacuum is not possible, make a manifold so that the refrigerant can be removed from
various parts of the system.
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