Daikin ARXC20BV1B, Installation Manual

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1-22
● Repair to intrinsically safe components
Do not apply any permanent inductive or capacitance loads to the circuit without ensuring that this will
not exceed the permissible voltage and current permitted for the equipment in use.
Replace components only with parts speci
fi ed by the manufacturer.
● Leak detection methods
Ensure that the detector is not a potential source of ignition (for example a halide torch) and is suitable
for the refrigerant used. Leak detection equipment shall be set at a percentage of the LFL of the
refrigerant (for R32, LFL is 13%) and shall be calibrated to the refrigerant employed and the appropriate
percentage of gas (25% maximum) is con
fi rmed.
Leak detection fl uids 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 pipework.
If a leak is suspected, all naked
fl ames 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.
● 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
fl ammability is a
consideration. The following procedure shall be adhered to:
● remove refrigerant;
● purge the circuit with inert gas;
● evacuate;
● purge again with inert gas;
● open the circuit by cutting or brazing.
The refrigerant charge shall be recovered into the correct recovery cylinders. The system shall be
“
fl ushed” 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
fi ll until the working pressure is achieved, then venting
to atmosphere, and fi nally pulling down to a vacuum. This process shall be repeated until no refrigerant is
within the system. When the fi nal 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.
● Labelling
This unit shall be labelled ‘de-commissioned and emptied of refrigerant’. This label shall be dated
and signed. Ensure that there are labels on the equipment stating the equipment contains
fl ammable
refrigerant.
● Charging procedures
In addition to conventional charging procedures, the following requirements shall be followed.
– Ensure that contamination of different refrigerants does not occur when using charging equipment.
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 prior to charging the system with refrigerant.
– Label the system when charging is complete (if not already).
– Extreme care shall be taken not to over fi ll the refrigeration system.
Prior to recharging the system it shall be pressure tested with OFN. The system shall be leak tested
on completion of charging but prior to commissioning. A follow up leak test shall be carried out prior to
leaving the site.