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Posted By GavinR
Hi Guys,
I need abit of advice regarding standard of equipment in relation to ATEX. We have a few dust extraction units for the collection of graphite dust and other such dusts which are of a fine nature and identified as a potential explosive dust. The main dust collection units with filters have been designed with explosion venting units but the info plate on the units only state the units are CE Marked and nothing else. The motor for the extraction unit has a info plate attached indicating it is EX and the necessary classification as identicated by our DSEAR assessment. The overall Declaration of conformity provides not information regarding the classification of equipment. I'm just a little confused to be honest why the extractor unit itself is not classified as ATEX only CE Marked. Our DSEAR Assessment identifies the inside of the unit as being Zone 20.
Can anyone share any experiences or their knowledge with me on this matter?
Cheers.
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Rank: Guest
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Posted By Peter How
Gavin
You correctly identify that you are under ATEX and you are handling flammable dusts. I also suspect that zone 20 is an appropriate zoning for the internals of the dustraction system. I also suspect the the external motor is supplied to a category meeting Zone 22. The motor will have an Ex nameplate.
The internals of the dustraction system are a different beast. There is a dust explosive atmosphere continuously present (fuel), there is air (oxygen) so safety must be provide by the "avoidance of effective ignition sources" [BSEN 1127-1:2007]. Ignition is the 3rd side of the fire triangle.
However most dustraction equipment suppliers cannot guarentee this absence of an internal ignition source. SO they rely on Para 6.5 of the BS1127 to "limit the effects of an explosion to a safe level" by 6.5.1b) Explosion relief.
Atex and the EPS Regs are about preventing ignitions using Harmonised Standards 60079 series. If you can't do this , then you can't put an Ex mark on.
hope this helps
regards
Peter
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Rank: Guest
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Posted By GavinR
Hi Peter,
Thanks for your response. That is a very helpful explanation and it makes prefect sense to me now. Thanks very much, i now do not feel as foolish as earlier this afternoon when trying to work the requirements out!
Cheers, Gavin
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