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refrigerant leaks. A halide torch (or any other detector using an open flame) should not be used.
6.
LEAK DETECTION METHODS
The following leak detection methods are considered acceptable for systems containing
flammable refrigerants. Electronic leak detectors should be used to detect flammable
refrigerants, but the sensitivity may not be adequate or require recalibration (detection
equipment should be calibrated in an area without refrigerant). Make sure that the detector is
not a potential source of ignition and that it is suitable for the refrigerant used. Leak detection
equipment should be set to a percentage of the LLI of the refrigerant and should be calibrated
with the refrigerant being used and the appropriate gas percentage (25% maximum) is
confirmed. Leak detection fluids can be used with most refrigerants, however, the use of
detergents containing chlorine should be avoided as chlorine can react with the refrigerant and
cause corrosion of copper pipes. If a leak is suspected, all open flames should be removed /
extinguished. If a refrigerant leak requiring brazing is detected, all refrigerant should be
recovered from the system or isolated (using shutoff valves) in a part of the system remote from
the leak. The oxygen free nitrogen (OFN) must then be purged through.
the system before and during the brazing process. If a refrigerant leak requiring brazing is
detected, all refrigerant should be recovered from the system or isolated (using shutoff valves)
in a part of the system remote from the leak. The oxygen free nitrogen (OFN) must then be
purged through the system before and during the brazing process. If a refrigerant leak requiring
brazing is detected, all refrigerant should be recovered from the system or isolated (using
shutoff valves) in a part of the system remote from the leak. The oxygen free nitrogen (OFN)
must then be purged through the system before and during the brazing process.
7.
DRAINING AND EVACUATION
When entering the refrigerant circuit for repairs - or for any other purpose - use standard
procedures. However, it is important to follow best practices as flammability is a factor to
consider. The following procedure must be observed: drain the refrigerant; purge the circuit with
inert gas; clear out ; purge again with inert gas; open the circuit by cutting or soldering. The
refrigerant charge must be collected in the correct recovery bottles.
The system must be "flushed" with OFN to make the unit safe. It may be necessary to repeat
this process several times. Compressed air or oxygen should not be used for this task. Draining
should be accomplished by breaking the vacuum in the system with OFN and continuing to fill
until operating pressure is reached, then releasing into atmosphere and ultimately pulling
vacuum. This process should be repeated until there is no more refrigerant in the system. When
the last OFN charge is used, the system must be vented to atmospheric pressure to allow work
to be performed. This operation is absolutely vital for brazing work to be carried out on the
piping.
8.
CHARGING PROCEDURES
In addition to conventional charging procedures, the following requirements must be observed.
• Make sure that the various refrigerants are not contaminated when using charging equipment.
Pipes or conduits should be as short as possible to minimize the amount of refrigerant they
contain.
• The bottles must be kept upright.
• Make sure the refrigeration system is grounded before charging it with refrigerant.
• Label the system when charging is complete (if not already done).
• Care should be taken not to overfill the refrigeration system.
Before recharging the system, it should be pressure tested with OFN. The system should be leak
tested at the end of charging but before commissioning. A leak test must be carried out before
leaving the site.
9.
DECOMMISSIONING
Before performing this procedure, it is essential that the technician is familiar with the equipment
and all of its details. It is recommended, in accordance with good practice, to collect all
refrigerants safely. Before performing the task, an oil and refrigerant sample should be taken in
case analysis is required before reusing the recovered refrigerant. It is essential that the power
supply is available before the start of the task.
a)
Familiarize yourself with the equipment and its operation.
b)
Electrically isolate the system.
c)
Before starting the procedure, make sure that: mechanical handling equipment is
available, if necessary, for handling the refrigerant cylinders; all personal protective equipment
is available and used correctly; the recovery process is continuously supervised by a competent
person; recovery equipment and cylinders meet appropriate standards.
d) Pump the refrigerant system, if possible.
e) If vacuum is not possible, create a manifold so that refrigerant can be drained from
different parts of the system.
f) Make sure the bottle is placed on the scale before recovery.
g) Start the recovery machine, then operate according to the manufacturer's instructions.
h) Do not overfill the bottles (not more than 80% of the volume in liquid charge).
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