UFESA DH5010 Manual De Instrucciones página 40

If a leak is suspected, all naked flames shall be removed/ extin uished.
If a leaka e of refri erant is found which requires brazin , all of the refri erant shall be recovered from the
system, or isolated (by means of shut o valves) in a part of the system remote from the leak. Oxy en
free nitro en (OFN) shall then be pur ed throu h the system both before and durin the brazin process.
Removal and evacuation
When breakin into the refri erant circuit to make repairs-or for any other purpose-conventional proce-
dures shall be used. However, it is important that best practice is followed since flammability is a consid-
eration. The followin procedure shall be adhered to:
• remove refri erant ;
• pur e the circuit with inert as;
• evacuate;
• pur e a ain with inert as;
• open the circuit by cuttin or brazin .
The refri erant char e shall be recovered into the correct recovery cylinders. The system shall be
"flushed"with octafluoronaphthalene (OFN) to render the unit safe. This process may need to be repeated
several times. Compressed air or oxy en shall not be used for this task.
Flushin shall be achieved by breakin the vacuum in the system with OFN and continuin to fill until the
workin pressure is achieved, then ventin to atmosphere, and finally pullin down to a vacuum.
This process shall be repeated until no refri erant is within the system. When the final OFN char e is
used, the system shall be vented down to atmospheric pressure to enable work to take place. This oper-
ation is absolutely vital if brazin operations on the pipe-work are to take place.
Ensure that the outlet for the vacuum pump is not close to any i nition sources and there is ventilation
available.
Char in procedures
In addition to conventional char in procedures, the followin requirements shall be followed.
- Ensure that contamination of di erent refri erants does not occur when usin char in equipment.
Hoses or lines shall be as short as possible to minimise the amount of refri erant contained in them.
- Cylinders shall be kept upri ht.
- Ensure that the refri eration system is earthed prior to char in the system with refri erant.
- Label the system when char in is complete (if not already).
- Extreme care shall be taken not to overfill the refri eration system.
40