Metal cutting - oxyfuel cutting, plasma cutting, machining, grinding, and other preparatory work.
drummerdimitri
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    Sun Oct 04, 2020 7:57 am
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    Beirut, Lebanon

So I'm planning to purchase a CNC plasma table for my metal fabrication shop, and I need to know a few details in order to budget for the installation of the unit.

Firstly, as I have decided on going for a downdraft table to clear the relatively small shop of toxic fumes, I am faced with two options: Fume extraction without any filters to the roof of the building or a filtered fume extractor that re-circulates the filtered air back into the shop.

I'd rather go extract directly out of the workshop as that will be the cheaper solution on the long run as I will not have to be constantly facing the inevitable filter change.

That being said, does anyone have any idea how long these filters last? I know it's almost impossible to say with any amount of certainty so lets take a worst case scenario of 8 hours/day of cutting aluminum sheets with a thickness of 20mm.

Also, are plasma cutting fumes hot? The reason I ask is so that I can price the ducting work accordingly. Might have to insulate the pipes from heat to prevent any potential skin burns.

Finally, if I decide to go for the fume extraction on the roof method, can I reduce the ducting diameter if it goes straight up for about 10 meters? My plasma table has an airflow requirement of 3500 m3/h and the outlet diameter is 310 mm. Will it be ok to reduce that directly to say 200 mm and go up from there?
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    Thu Dec 26, 2013 12:41 am
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    Laredo, Tx

The smoke has a lot of particles that I think will clog up filters fast. It also creates a lot of Carbon monoxide that will set off detectors real fast. I think it would be best to dump directly outside your shop instead of filtration. I'm also getting ready to set up a cnc table, and will definitely be ducting outside my garage while drawing in fresh air.
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Toggatug
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    Sat Mar 25, 2017 12:06 pm
  • Location:
    Ontario, Canada

I see alot of tables setup with a waterbath underneath, not sure if that's all there is too it, perhaps there's a smoke extraction ring around the table like a indoor bbq restaurant has built into the tables.

Might be something to look into since water is cheap and would catch the particles
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