Publicité
4 - EXPLANATORY NOTE RELATING TO ATEX DIRECTIVE 94/9/EC
Published in the Official Journal of the European Community on April 19
NOTE FOR CUSTOMERS USING AUTOMATIC CUTTING MACHINES
1) Why this machine is not designed for use in explosive atmospheres
Cutting machines comprising an oxygen and gas torch or a plasma torch use a source of heat created by a flame or an electric arc.
Explosions can occur in explosive atmospheres when the following simultaneous conditions are met:
-
presence of combustible material
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presence of oxidant (air, oxygen)
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mixture of combustible gas and oxidant in the explosiveness range = for example, the mixture of (natural
gas) methane and air is flammable at an atmospheric pressure between 5% and 15%
-
presence of a source of ignition
The cutting process necessarily involves a source of ignition and molten metal slag is also a source of ignition. That is why the machine may
not be used in workshops in which an explosive atmosphere is created by processes other than cutting machines or similar
machines.
2) Why the ATEX Directive applies to this machine
The combustible gases used by flame cutting torches may be natural gas (methane), propane or acetylene.
The oxidant gas is oxygen.
The gases used in plasma torches may be neutral gases (nitrogen, argon), combustible gases (argon/hydrogen, methane), oxidant gases
(oxygen) or a mixture of some these gases.
Also, all theses gases are colourless and most of them are odourless and are therefore not even detected by the operator.
The gases are brought into the workshop close to the supplied machine and the machine includes a number of pipes and conduits. Leaks are
possible and can lead to the accumulation of combustible gases, which can in turn give rise to explosive atmospheres.
The machine and its gas supply may in themselves create explosive atmospheres.
For safety, it is therefore indispensable for the machine to be installed in a large well-ventilated area and the cut material must necessarily be
placed on a suction table that carries away burnt gases and also removes any unburned combustible gases that may be present near the
plasma or other torches as a result of a leak.
3) Safe machine design
All the circuits that carry gas are placed in the open air or in very well ventilated casings.
The electrical circuits are placed in closed cabinets or casings in accordance with the ATEX Directive.
No party other than the manufacturer or a party formally authorised by the manufacturer may modify the configuration of the gas
circuits or the electrical cabinets.
Otherwise, the manufacturer shall cease to be liable for the conformity or the guarantee. The covers of the casings must be kept closed, also in
order to keep out dust and slag.
4) Machine category
According to the criteria of the ATEX Directive, the machine is classified as follows:
Equipment group II
Category 3
That is, in short:
"Equipment intended for use in areas in which explosive atmospheres caused by gases are unlikely to occur, or, if they do occur, are likely to do
so infrequently and for a short period only. Equipment in this category ensures the requisite level of protection during normal operation".
"The manufacturer must, in order to affix the CE marking, follow the procedure relating to internal control of production".
"The manufacturer must issue a declaration of conformity."
"The manufacturer must take all the measures required to ensure that the manufacturing process ensures the conformity of the manufactured
equipment to the technical documentation..."
5) Declaration, quality assurance
The manufacturer has a Quality Assurance system under ISO 9001, and offers assurance that the design and manufacturing are in accordance
with the applicable process requirements. Each machine undergoes unit verification.
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8695 7050
th
1994
SAFETY
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