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Specialist's Manual
wed since flammability is a consideration. The foll-
owing 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. For appliances contain-
ing flammable refrigerants, the system shall be "fl-
ushed" with OFN to render the unit safe. This pro-
cess may need to be repeated several times. Co-
mpressed air or oxygen shall not be used for purging
refrigerant systems.
For appliances containing flammable refrigerants,
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 pipe-work are to take
place.
Ensure that the outlet for the vacuum pump is not
close to any ignition sources and that ventilation
is available.
Charging procedures
In addition to conventional charging procedures,
the following requirements shall be followed.
Ensure that contamination of different refrige-
–
rants does not occur when using charging
uipment. 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 pressu-
re-tested with the appropriate purging gas.
–
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.
Decommissioning
Before carrying out this procedure, it is essential that
the technician is completely familiar with the equipm-
ent 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.
a) Become familiar with the equipment and its ope-
ration.
b)
Isolate system electrically.
c)
Before attempting the procedure, ensure that:
mechanical handling equipment is available, if
required, 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 accord-
ance with manufacturer's instructions.
h)
Do not overfill cylinders. (No more than 80 % volu-
me liquid charge).
i)
Do not exceed the maximum working pressure of
the cylinder, even temporarily.
j) When the cylinders have been filled correctly and
the process completed, make sure that the cylind-
ers and the equipment are removed from site pro-
mptly and all isolation valves on the equipment are
closed off.
k)
Recovered refrigerant shall not be charged into an-
eq-
other refrigeration system unless it has been clea-
ned and checked.
Labelling
Equipment shall be labelled stating that it has been de-
commissioned and emptied of refrigerant. The label
shall be dated and signed. For appliances containing
flammable refrigerants, ensure that there are labels on
the equipment stating the equipment contains flamm-
able refrigerant.
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
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