A5P | 01
MAINTENANCE
13.Leak detection methods
The following leak detection methods are acceptable
for systems containing ammable refrigerant.
Electronic leak detectors shall be used to detect
ammable refrigerants, but the sensitivity may not
be adequate, or may need recalibration (Detection
equipment shall be calibrated in a refrigerant-free
area.) Ensure that detector is not a potential source of
ignition and is suitable for the refrigerant used.
Leak detection 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 pipe-work.
If a leak is suspected, all naked ames shall be
removed/extinguished.
If a leak of refrigerant is found which requires brazing,
all of the refrigerant shall be recovered from the
system. Oxygen free nitrogen (OFN) shall then be
purged through the system both before and during the
brazing process.
14.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”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 ll until
the working pressure is achieved, then venting to
atmosphere, and nally pulling down to a vacuum.
This process shall be repeated until no refrigerant is
within the system. When the 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 pipework are to take place. Ensure that the
outlet for the vacuum pump is not close to any ignition
sources and there is ventilation available.
15.Refrigerant Charging procedures.
In addition to conventional charging procedures, the
following requirements shall be followed.
-Ensure that contamination of dierent refrigerants
does not occur when using charging equipment.
Hoses or lines shall be as short as possible to
minimize 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 overll 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 commissioning. A
follow up leak test shall be carried out prior to leaving
the site.
16.Decommissioning
Before carrying out this procedure, it is essential that
technician is completely familiar with the equipment
and all its detail. It 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 reuse of
reclaimed refrigerant. It is essential that electrical power
is available before the task is commenced.
Become familiar with the equipment and its operation.
b) Isolate system electrically.
c) Before attempting the procedure ensure that:
mechanical handling equipment is available, if repaired,
for handling refrigerant cylinders; all personal protective
equipment is available and being used correctly;
the recovery process is supervised at all times by a
competent person; recovery equipment and cylinders
conform to the appropriate standards.
d) Pump down refrigerant system, if possible.
e) if a vacuum is not possible, make a manifold so that
refrigerant can be removed from various parts of the
system.
f) Make sure that cylinder is situated on the scales
before recovery takes place.
g) Start the recovery machine and operate in
accordance with manufacturer’s instructions.
h) Do not overll cylinders (No more than 80% volume
liquid charge).
i) Do not exceed the maximum working pressure of the
cylinder, even temporarily.
j) When the cylinders have been lled correctly and the
process completed, make sure that the cylinders and
the equipment are removed from site promptly and all
isolation valves on the equipment are closed o.
k) Recovered refrigerant shall not be charged into
another refrigeration system unless it has been cleaned
and checked.
17.Labelling
Equipment shall be labelled stating that it has been
decommissioned and emptied of refrigerant. The label
shall be dated and signed. Ensure that there are labels
on the equipment stating the equipment contains
ammable refrigerant.
18.Recovery
When removing refrigerant from a system, either for
servicing or decommissioning, it is recommended good
practice that all refrigerants are removed safely.
When transferring refrigerant into cylinders, ensure
that only appropriate refrigerant recovery cylinders are
employed. Ensure that the correct number of cylinders
for holding the total system charge are available. All
cylinders to be used are designed for the recovered
refrigerant and labelled for that refrigerant(i.e.-special
cylinders for the recovery of refrigerant). Cylinders shall
be complete with pressure relief value and associated
shut-o values in good working order. Empty recovery
cylinders are evacuated and, if possible, cooled before
recovery occurs.
The recovery equipment shall be in good working order
with a set of instructions concerning the equipment
that is at hand and shall be suitable for the recovery of
ammable refrigerants.
In addition, a set of calibrated weighing scales shall
be available and in good work order. Hoses shall be
complete with leak-free disconnect couplings and in
good condition.
Before using the recovery machine, check that it is in
satisfactory working order, has been properly maintained
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