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Specialist's Manual
oxygen-free nitrogen 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 potential ignition
sources and that ventilation is available.
Charging procedures
In additon 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 in an appropriate position according to the instructions.
Ensure that the refrigerating 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 refrigerating 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 reuse 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.
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