11
CAUTION
7.
Removal and evacuation
When breaking into the refrigerant circuit to make repairs – or for any other purpose – conventional procedures shall be used.
However, it is important that best practice is followed since flammability is a consideration.
The following procedure shall be adhered to:
• remove refrigerant -> • purge the circuit with inert gas -> • evacuate -> • purge again with inert gas ->
• open the circuit by cutting or brazing
The refrigerant charge shall be recovered into the correct recovery cylinders.
The system shall be purged with OFN to render the appliance safe. (remark: OFN = oxygen free nitrogen, type of inert gas)
This process may need to be repeated several times.
Compressed air or oxygen shall not be used for this task.
Purging 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 pipe work are to take place.
• Ensure that the outlet for the vacuum pump is not close to any potential 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 minimize 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 over fill the refrigerating system.
Prior to recharging the system it shall be pressure tested with OFN (refer to #7).
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.
Electrostatic charge may accumulate and create a hazardous condition when charging and discharging the refrigerant.
To avoid fire or explosion, dissipate static electricity during transfer by grounding and bonding containers and equipment before
charging/discharging.
9.
Decommissioning
Before carrying out this procedure, it is essential that the technician is completely familiar with the equipment and all its details.
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 instructions.
h)
Do not over fill 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.
Electrostatic charge may accumulate and create a hazardous condition when charging or discharging the refrigerant.
To avoid fire or explosion, dissipate static electricity during transfer by grounding and bonding containers and equipment before
charging/discharging.
10.
Labelling
Equipment shall be labelled stating that it has been de-commissioned and emptied of refrigerant.
The label shall be dated and signed.
Ensure that there are labels on the equipment stating the equipment contains flammable refrigerant.
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