Midea MAP05S1AWT-A User Manual page 12

For units containing flammable refrigerants, refrigerants purging shall be achieved
by breaking the vacuum in the system with oxygen-free nitrogen and continuing
to fill until the working pressure is achieved, then venting to atmosphere, and finally
pulling down to a vacuum (optional for A2L). This process shall be repeated until
no refrigerant is within the system (optional for A2L). When the final oxygen-free
nitrogen charge is used. the system shall be vented down to atmospheric pressure
to enable work to take place.
The outlet for the vacuum pump shall not be close to any potential ignition sources,
and ventilation shall be available.
12. Charging procedures
In addition to conventional charging procedures, the following requirements shall
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 in an
appropriate position according to the instructions. 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.
13. Decommissioning
Before carrying out this procedure, it is essential that the technician is completely
familiar with the unit 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 unit 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 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
k) Recovered refrigerant shall not be charged into another refrigeration system
unless it has been cleaned and checked.
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