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NOTE : Examples of leak detection fluids are
- bubble method,
- fluorescent method agents.
If a leak is suspected, all naked flames shall be removed/extinguished. If a leakage of refrigerant is found which requires brazing, all of the
refrigerant shall be recovered from the system, or isolated (by means of shut off valves) in a part of the system remote from the leak. Removal
of refrigerant shall be according to 7 removal and evacuation.
7. REMOVAL AND EVACUATION
When breaking into the refrigerant circuit to make repairs – or for any other purpose – conventional procedures shall be used. However, for
flammable refrigerants it is important that best practice be followed, since flammability is a consideration. The following procedure shall be
adhered to:
a) safely remove refrigerant following local and national regulations.
b) purge the circuit with inert gas.
c) evacuate. (optional for A2L)
d) purge with inert gas. (optional for A2L)
e) open the circuit by cutting or brazing.
The refrigerant charge shall be recovered into the correct recovery cylinders if venting is not allowed by local and national codes. For appliances
containing flammable refrigerants, the system shall be purged with oxygen-free nitrogen to render the appliance safe for flammable refrigerants.
This process might need to be repeated several times. Compressed air or oxygen shall not be used for purging refrigerant systems. For
appliances 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.Ensure that the outlet for the vacuum pump is not
close to any ignition sources and there is ventilation available.
8. 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.
9. 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.
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ARP-2410
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