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Idiomas disponibles
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● Repairing intrinsically safe components can be done while they are live in the
presence of a flammable atmosphere.
However, before applying any permanent inductive or capacitance loads to the circuit,
ensure this will not exceed the permitted voltage and current for the equipment in use.
Also, ensure the test apparatus is rated correctly. Do not work on non-intrinsically safe
components in the presence of a flammable atmosphere.
● Only replace components with parts specified by the manufacturer. Non-specified
parts could release flammable components into the atmosphere.
● Keep cabling away from sharp edges, vibrations and excessive pressure. Check for
damages and wear and tear to the cabling.
● Never use sources of ignition (halide torches or other naked flames) to search for
refrigerant leaks. It is acceptable to use the following leak detection methods for
systems containing flammable refrigerants:
- Electronic leak detectors: Be aware, the sensitivity of electronic detectors may need to
be recalibrated. Ensure the equipment is not a potential source of ignition. Equipment
must be calibrated in a refrigerant-free area and set at a percentage of the LFL of the
refrigerant, with a maximum of 25% gas.
- Leak detection fluids: These can be used, but detergents with chlorine should be
avoided to prevent corrosion of copper pipework.
- If a leak is suspected, all naked flames must be removed and extinguished. If a
refrigerant leakage is found that requires brazing, it must be removed from the system
or isolated using shut-off valves in a remote part of the system. Oxygen-free nitrogen
(OFN) should then be purged through the system before and during the brazing
process.
● When accessing the refrigerant circuit for repairs or any other purpose, it is crucial to
follow proper procedures with safety in mind. To ensure the safety of the personnel
involved, the following steps must be taken:
1) Remove refrigerant.
2) Purge the circuit with inert gas.
3) Evacuate the circuit.
4) Purge again with inert gas.
Open the circuit by cutting or brazing.
The refrigerant must be removed and collected in the correct cylinders. The system then
needs to be flushed with oxygen-free nitrogen (OGN) until no refrigerant remains. This
is done by filling the system with OFN, venting into the atmosphere and repeating until
no refrigerant is left. Do not use compressed air or oxygen. This flushing process must
be repeated several times and the charge of OFN must be vented into the atmosphere.
It is important to make sure the vacuum pump outlet is not near any ignition sources and
that there is enough ventilation available. Flushing is crucial before brazing the
pipework.
Charging procedures
When charging a refrigeration system, it is important to follow these additional
requirements:
● Use charging equipment that prevents contamination of different refrigerants. Keep
hoses or lis as short as possible, minimising the amount of refrigerant they contain.
● Keep cylinders upright.
● Before charging the system with refrigerant, ensure the refrigeration system is
properly grounded.
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