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1. Safety precautions
• When breaking into the refrigerant circuit to make
repairs – or for any other purpose conventional
procedures shall be used. However, for flammable
refrigerants it is important that best practice is fol-
lowed since flammability is a consideration. The fol-
lowing procedure shall be adhered to:
- remove refrigerant
en
- 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
"flushed" with OFN to render the unit safe. This pro-
cess may need to be repeated several times.
Compressed 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 atmos-
pheric 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.
• 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. Hos-
es 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 al-
ready).
- Extreme care shall be taken not to overfill the refrigera-
tion system.
Prior to recharging the system, it shall be pressure-
tested with the appropriate purging gas. The system
shall be leaktested on completion of charging but
prior to commissioning. A follow up leak test shall
be carried out prior to leaving the site.
7
• Before carrying out this procedure, it is essential
that the 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 re-use of reclaimed refrigerant. It
is essential that electrical power is available before
the task is commenced.
a) 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 re-
quired, for handling refrigerant cylinders;
- all personal protective equipment is available and be-
ing used correctly;
- the recovery process is supervised at all times by a
competent person;
- recovery equipment and cylinders conform to the ap-
propriate standards.
d) If a vacuum is not possible, make a manifold so that
refrigerant can be removed from various parts of the
system.
e) Make sure that cylinder is situated on the scales be-
fore recovery takes place.
f) Start the recovery machine and operate in accord-
ance with manufacturer's instructions.
g) Do not overfill cylinders. (No more than 80 % volume
liquid charge).
h) Do not exceed the maximum working pressure of the
cylinder, even temporarily.
i) When the cylinders have been filled 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 off.
j) Recovered refrigerant shall not be charged into an-
other refrigeration system unless it has been cleaned
and check.
Continued to next page.
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