INVENTOR V7KI-18WiFiR/U7RS-18 Installationshandbuch Seite 33

11. 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. Intrinscially safe
components are the only types that can be worked on while live in the presence of a flammable atmo-
sphere. The test apparatus shall be at the correct rating.
Replace components only with parts specified by the manufacturer. Other parts may result in the igni-
tion of refrigerant in the atmosphere from a leak.
12. 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.
13. 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.
14. 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 sensi-
tivity 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. 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 or extinguished. If a leakage of refrigernat 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.
15. Removal and evacuation
When breaking into the refrigerant circuit to make repairs of 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. Com-
pressed 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.
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