8 (48)
10. DETECTION OF FLAMMABLE REFRIGERANTS
Under no circumstances shall potential sources of ignition be used in the searching for detection or refrigerant leaks.
A halide torch (or any other detector using a naked flame) shall not be used.
11. LEAK DETECTION METHODS
The following leak detection methods are deemed acceptable for systems containing flammable refrigerants. Electronic
leak detectors shall be used to detect flammable refrigerants, but the sensitivity may not be adequate, or may need re-
calibration. (Detection equipment shall be calibrated in a refrigerant-free area.) Ensure that the detector is not a potential
source of ignition and is suitable for the refrigerant used. Leak detection equipment shall be set at a percentage of the LFL
of the refrigerant and shall be calibrated to the refrigerant employed and the appropriate percentage of gas (25 % maxi-
mum) is confirmed. Leak detection fluids are suitable for use with most refrigerants, but the use of detergents containing
chlorine shall be avoided as the chlorine may react with the refrigerant and corrode the copper pipe-work. If a leak is sus-
pected, 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. Oxygen free nitrogen (OFN) shall then be purged through the system before and during the brazing process.
12. 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 the best practice is followed since flammable is a consideration. The following proce-
dure 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 chare shall be recovered into the correct recovery cylinders. The system shall be “flushed” with OFN to ren-
der the unit safe. This process may need to be repeated several times. Compressed air 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. Then the final OFN charge is used, the system shall be vented down to atmosphe-
ric 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 ignition sources and there is ventilation available.
13. 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 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. They 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.
14. 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.
1. Become familiar with the equipment and its operation.
2. Isolate system electrically.
3. Before attempting the procedure ensure that:
3.1. Mechanical handling equipment is available, if required, for handling refrigerant cylinders.
3.2. All personal protective equipment is available and being used correctly.
3.3. The recovery process is supervised at all times by a competent person.
3.4. Recovery equipment and cylinders conform to the appropriate standards.
4. Pump down refrigerant system, if possible.
5. If a vacuum is not possible, make a manifold so that refrigerant can be removed from various parts of the system.
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