8
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 press-
ure 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 there is ventilation available.
13.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.
14.Decommissioning
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 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 accordance with manufacturer's instructions.
h)Do not overfill 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 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.
k)Recovered refrigerant shall not be charged into another refrigeration system unless it has been cleaned and checked.
15.Labelling
Equipment shall be labelled stating that it has been de-commissioned and emptied of refrigerant. The label shall be dated
and signed. Ensure that there are labels on the equipment stating the equipment contains flammable refrigerant.
16.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 is avail-
able. All cylinders to be used are designated 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 valve and associated shut-off
valves 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 flammable refrigerants.In addition, a set of calibrated weighing scales shall
be available and in good working order. Hoses shall be complete with leak-free disconnect couplings and in good cond-
ition. Before using the recovery machine, check that it is in satisfactory working order, has been properly maintained and
that any associated electrical components are sealed to prevent ignition in the event of a refrigerant release. Consult
manufacturer if in doubt.
The recovered refrigerant shall be returned to the refrigerant supplier in the correct recovery cylinder, and the relevant
Waste Transfer Note arranged. Do not mix refrigerants in recovery units and especially not in cylinders. If compressors or
compressor oils are to be removed, ensure that they have been evacuated to an acceptable level to make certain that
flammable refrigerant does not remain within the lubricant. The evacuation process shall be carried out prior to returning
the compressor to the suppliers. Only electric heating to the compressor body shall be employed to accelerate this process.
When oil is drained from a system, it shall be carried out safely.
