Daikin CTX Series Service Manual page 11

Safety Cautions
Safety Checklist (con't)
 Leak detection methods
 Removal and evacuation
 Charging procedures
6
The following leak detection methods can be applied for systems containing R410A.
Electronic leak detectors shall be used to detect R410A, 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:
 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.
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.
 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.
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.
DAMA-SM-21-003
Introduction