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Idiomas disponibles
Idiomas disponibles
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 flammable
atmosphere. The test apparatus shall be at the correct rating. Replace components only with parts
specified 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 flame) shall not be used.
6 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 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 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.
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 "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 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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