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English
4. 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 speci
fi
ed
by the manufacturer. Unspeci
fi
ed parts by
manufacturer may result ignition of refrigerant
in the atmosphere from a leak.
5. 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.
6. Detection of
fl
ammable refrigerants
• Under no circumstances shall potential
sources of ignition be used in the searching or
detection of refrigerant leaks.
• A halide torch (or any other detector using a
naked
fl
ame) shall not be used.
7. Leak detection methods
The following leak detection methods are
deemed acceptable for all refrigerant systems.
• No leaks shall be detected when using
detection equipment with a capability of 10
−
6
Pa·m
3
/s or better, for example, a helium
sniffer.
• Electronic leak detectors may be used
to detect
fl
ammable 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 con
fi
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.
OFN = oxygen free nitrogen, type of inert gas.
8. 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
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 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.
Safety precautions
ACXF55-17110_YA0518-0.indb 27
ACXF55-17110_YA0518-0.indb 27
3/8/2018 9:44:42 AM
3/8/2018 9:44:42 AM