Ruby AFC-9001 Manual De Instrucciones página 48

preventing the ingress of fl ammable atmospheres. Replacement parts shall be in accordance with the
manufacturer's specifi cations.
NOTE The use of silicon sealant may inhibit the effectiveness of some types of leak detection equipment.
Intrinsically safe components do not have to be isolated prior to working on them.
3 REPAIR TO INTRINSICALLY SAFE COMPONENTS
Do not apply any permanent inductive or capacitance loads to the circuit without ensuring that this will
not exceed the permissible voltage and current permitted for the equipment in use.
Intrinsically safe components are the only types that can be worked on while live in the presence of a
fl ammable atmosphere. The test apparatus shall be at the correct rating. Replace components only
with parts specifi ed by the manufacturer. Other parts may result in the ignition of refrigerant in the
atmosphere from a leak.
4 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.
5 DETECTION OF FLAMMABLE REFRIGERANTS
Under no circumstances shall potential sources of ignition be used in the searching for or detection of
refrigerant leaks. A halide torch (or any other detector using a naked fl ame) shall not be used.
6 LEAK DETECTION METHODS
The following leak detection methods are deemed acceptable for systems containing fl ammable
refrigerants. Electronic leak detectors shall be used to detect fl ammable refrigerants, but the sensitivity
may not be adequate, or may need recalibration. (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
confi rmed. Leak detection fl uids 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 fl ames 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.
7 REMOVAL AND EVACUATION
When breaking into the refrigerant circuit to make repairs – or for any other purpose – con- ventional
procedures shall be used.However, it is important that best practice is followed since fl ammability 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 "fl ushed" 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 fi ll until the working pressure is achieved, then venting to atmosphere, and fi nally
pulling down to a vacuum. This process shall be repeated until no refrigerant is within the system. When
the fi nal 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 pipework are to take place.
Ensure that the outlet for the vacuum pump is not close to any ignition sources and there is ventilation available.
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