Hkoenig KOL7812 Manual De Usuario página 20

6. Leak detection methods
The following leak detection methods are deemed acceptable for systems containing
flammable refrigerants.
Electronic leak detectors shall be used to detect flammable refrigerants, but the sensitivity may
not be adequate, or may need re-calibration. (Detection equipment shall be calibrated in a
refrigerant-free area.) Ensure that the detector is not a potential source of ignition and is
suitable for the refrigerant used. Leak detection equipment shall be set at a percentage of the
LFL of the refrigerant and shall be calibrated to the refrigerant employed and the appropriate
percentage of gas (25 % maximum) is confirmed.
Leak detection fluids are suitable for use with most refrigerants but the use of detergents
containing chlorine shall be avoided as the chlorine may react with the refrigerant and 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:
1) Remove refrigerant.
2) Purge the circuit with inert gas.
3) Evacuate.
4) Purge again with inert gas.
5) 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.
1) Ensure that contamination of different refrigerants does not occur when using charging
equipment. Hoses or lines shall be as short as possible to minimize the amount of refrigerant
contained in them.
2) Cylinders shall be kept upright.
3) Ensure that the refrigeration system is earthed prior to charging the system with refrigerant.
4) Label the system when charging is complete (if not already).
5) Extreme care shall be taken not to overfill the refrigeration system.