24
Installation and Maintenance
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 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 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.
1.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.
2.Cylinders shall be kept upright.
3.Ensure that the refrigeration system is earthed prior to charging
the system with refrigerant.
4.Label the system when charging is complete (if not already).
5.Extreme care shall be taken not to overfill the refrigeration
system.
Prior to recharging the system, it shall be pressure-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 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 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.
●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 flammable 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 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 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 shuto 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 all appropriate refrigerants
including, when applicable, 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 condition. 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
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