DC Inverter U-match Series Floor Ceiling Type Unit
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consideration. The following procedure shall be adhered to
：
(1) Remove refrigerant;
(2) Purge the circuit with inert gas;
(3) Evacuate;
(4) Purge again with inert gas;
(5) Open the circuit by cutting or brazing.
The refrigerant charge shall be recovered into the correct recovery
cylinders. The system shall be “flushed” with OFN to r
ender 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 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 pipework are to take place.
Ensure that the outlet for the vacuum pump is not close to any
ignition sources and there is ventilation available.
5.4.7 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 minimize the amount of refrigerant contained in
them.
(2) Cylinders shall be kept upright.
