Daikin FTXZ25NV1B Service Manual page 10

Safety Cautions
Under no circumstances shall potential sources of ignition be used in the search for or detection
of refrigerant leaks. A halide torch (or any other detector using a naked flame) shall not be used.
The following leak detection methods can be applied for systems containing R-32.
Electronic leak detectors shall be used to detect R-32, 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 that it is suitable for the
refrigerant used. Leak detection equipment shall be set to the percentage of the lower
flammability limit (LFL) of the refrigerant and calibrated to fit the refrigerant employed. The
appropriate percentage of gas (maximum 25%) shall be 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 piping work.
If a leak is suspected, all naked flames shall be removed or extinguished.
If a refrigerant leakage which requires brazing is found, 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 point of the leakage. Oxygen free nitrogen (OFN) shall then be purged through the system
both before and during the brazing process.
When breaking the refrigerant circuit to make repairs or any other purpose, conventional
procedures may be used. However, flammability must be taken into consideration. The
following procedure shall be adhered to:
The refrigerant shall be recovered into the correct recovery cylinders. The system shall be
cleaned with OFN to render the unit safe. (= Flushing) This process may need to be repeated
several times. Compressed air or oxygen shall not be used for this task.
Flushing shall be achieved through breaking the vacuum by filling the system with OFN until the
working pressure is achieved, then venting the OFN into the atmosphere, and finally pulling the
system down to vacuum again. This process shall be repeated until no refrigerant remains
within the system. After the last OFN charge is finished, the system shall be vented down to
atmospheric pressure to enable work. This operation is especially important if brazing
operations on the piping work are to take place.
Ensure that the outlet for the vacuum pump is not close to any ignition sources and that there is
ventilation available.
In addition to conventional charging procedures, the following requirements shall be met.
Ensure that the charging equipment to be used is not contaminated by different refrigerants.
Hoses or lines shall be as short as possible to minimise the amount of refrigerant contained in
them.
Before recharging, the system shall be tested for leakage with OFN. On completion of charging,
the system shall be tested before commissioning. Follow up leakage test shall be carried out
before leaving the site.
ix
Detecting of R-32
Leak detection methods
Removal and evacuation
• Remove refrigerant;
• Purge the circuit with inert gas;
• Evacuate the inert gas;
• Purge again with inert gas;
• Carry out cutting or brazing of the circuit.
Charging procedures
• Cylinders shall be kept upright.
• Ensure that the refrigeration system is earthed before charging the system with refrigerant.
• Label the system when charging is complete (if not already).
• Extreme care shall be taken not to overfill the refrigeration system.
SiMT041311E