Qlima D210 Manuel D'utilisation page 96

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 recalibration.
(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 pipework.
lf a leak is suspected, all open flames shall be removed/extinguished.
lf 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: 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 "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 pipework are to take place. Ensure that the outlet tor the vacuum
pump is not close to any ignition sources and !here is ventilation available.
8 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 overfill 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.
9 DECOMMISSIONING
Before carrying out this procedure, it is essential that the technician is completely
familiar with the equipment and all its detail. lt is recommended good practice that
all refrigerants are recovered safely. Prior to the task being carried out, an oil and
refrigerant sample shall be taken in case analysis is required prior to re-use of
reclaimed refrigerant. lt is essential that 4 GB electrical power is available before the
task is commenced.
a) Become familiar with the equipment and its operation.
b) lsolate system electrically.
c) Before attempting the procedure ensure that: mechanical handling equipment is
available, if required, for handling refrigerant cylinders;
d) All personal protective equipment is available and being used correctly; the
recovery process is supervised at all times by a competent person;
e) recovery equipment and cylinders conform to the appropriate standards.
f) Pump down refrigerant system, if possible.
g) lf a vacuum is not possible, make a manifold so that refrigerant can be removed
from various parts of the system.
h) Make sure that cylinder is situated on the scales before recovery takes place.
i) Start the recovery machine and operate in accordance with manufacturer's
instructions.
j) Do not overfill cylinders. (No more than 80 % volume liquid charge).
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