Structural Concepts OASIS C33R User Manual page 18

PREVENTIVE MAINTENANCE - TO BE PERFORMED BY TRAINED SERVICE PROVIDERS ONLY - 3 of 7
WARNING! TURN OFF CASE BEFORE PERFORMING PREVENTIVE MAINTENANCE!
Removal and evacuation
•
When breaking into the refrigerant circuit to make repairs-or for any other purpose-conventional proce-
dures shall be used. However, for flammable refrigerants it is important that the best practice be fol-
lowed, since flammability is a consideration. The following procedure shall be adhered to:
a) safely remove refrigerant following local and national regulations;
b) purge the circuit with inert gas;
c) evacuate (optional for A2L);
d) purge with inert gas (optional for A2L);
e) open the circuit by cutting or brazing.
• The refrigerant change shall be recovered into the correct recovery cylinders if venting is not allowed
by local and national codes. For appliances containing flammable refrigerants, the system shall be
purged with oxygen-free nitrogen to render the appliance safe for flammable refrigerants. This process
might need to be repeated several times. Compressed air or oxygen shall not be used for purging re-
frigerant systems.
• For appliances containing flammable refrigerants, refrigerant purging shall be achieved by breaking
the vacuum in the system with oxygen-free nitrogen and continuing to fill until the working pressure is
achieved, then venting to atmosphere, and finally pulling down to a vacuum (optional for A2L). This
process shall be repeated until no refrigerant is within the system (optional for A2L). When the final
oxygen-free nitrogen change is used, the system shall be vented down to atmospheric pressure to
enable work to take place.
• Ensure that the outlet for the vacuum pump is not close to any potential ignition sources and that ven-
tilation is available.
Charging procedures
• In addition to conventional charging procedures, the following requirements shall be followed.
a) Ensure that contamination of different refrigerants does not occur when using charging equip-
ment. Hoses or lines shall be as short as possible to minimize the amount of refrigerant con-
tained in them.
b) Cylinders shall be kept in an appropriate position according to the instructions.
c) Ensure that the REFRIGERATING SYSTEM is earthed prior to charging the system with refrig-
erant.
d) Label the system when charging is complete (if not already).
e) Extreme care shall be taken not to overfill the REFRIGERATING SYSTEM.
• Prior to recharging the system. It shall be pressure-tested with the appropriate purging gas. The sys-
tem shall be lead-tested on completion of charging but prior to commissioning. A follow up leak test
shall be carried out prior to leaving the site.
Maintenance and Service Notes
18