17
ENG
Replace components only with parts specified by the manufacturer. Other parts may result in the ignition of
refrigerant in the atmosphere from a leak.
19.
Cabling
Check that cabling will not be subject to wear, corrosion, excessive pressure, vibration, sharp edges or any
other adverse environmental effects. The check shall also take into account the effects of aging or continual
vibration from sources such as compressors or fans.
20.
Detection of flammable refrigerants
Under no circumstances shall potential sources of ignition be used in the searching for or detection of
refrigerant leaks. Ahalide torch (or any other detector using a naked flame) shall not be used.
21.
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 % maximum) 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 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. Oxygen free
nitrogen (OFN) shall then be purged through the system both before and during the brazing process.
22.
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 flushed
with OFN to render 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 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.
23.
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.
Summary of Contents for TT37AF-1232IAW
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