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Thread: Activated Charcoal not working

  1. #1

    Activated Charcoal not working

    I have a 40 watt epilog mini that is hooked up to a do-it-yourself fume extractor. After replacing the activated carbon there is no odor for about 8 hours of machine operation then the odor becomes increasingly detectable. So why isn't it lasting longer? I've heard other people say the same amount of charcoal lasts them an entire year.
    So the system is: machine-pipe-wooden filter box (prefilter, prefilter, 12" empty space, 5" tray (12"wide 24" long 5" deep) of loose activated carbon) pipe at bottom of box- blower - pipe then goes outside of building.
    It's the same story for:
    General Carbon C40 bituminous coal 4mm pellets
    Virgin Coconut Shell
    Thank you for any ideas or advice
    Last edited by Misty Smith; 06-09-2018 at 10:43 AM.

  2. #2
    You didn't mention what you are doing for those 8 hours (engraving powder coat, engraving or cutting wood/mdf, engraving or cutting acrylic, etc.) but cutting most stuff will typically clog up AC faster than engraving, and cutting plastics such as acrylic will definitely use up your AC faster than engraving powder coat or typical wood such as BB. Another thing is, you say you are using C40, which is a pelletized carbon in a 6x4 mm nominal size. I'm using 4x8S which is derived from coconut and is considered a granular carbon in a 4x8 mesh size, which is about 4.8x2.4 mm. Not sure what differences you would see between coal and coconut, but the GC rep recommended coconut to me for laser filter applications. As a guess, I would think the granular format would also last longer than pelletized due to higher surface area exposing more of the AC pores. Speaking of which, you also didn't mention what your prefilters are... They should be fairly high MERV to filter out smoke particles and smaller. Otherwise (e.g., if they are common furnace filters) they let way too many particulates through to the AC, and that will fairly quickly clog the AC, rendering it useless. Ideally, the only thing the carbon should have to deal with is odors, so a HEPA filter is usually recommended ahead of the AC bed. If your old carbon pellets look dirty gray or dusty rather than like new, then your prefilters are inadequate for what you are doing.

    I think I replace my HEPA filter 2-3 times before I replace the AC, and I replace my prefilters 3-6 times before I replace the HEPA, depending on how much BB and acrylic I'm doing. I monitor the pressure drops across each filter stage to determine when the different media get replaced. With something like cutting really smokey wood, you can clearly see the pressure drop rise across the prefilters over a matter of 15-20 minutes.

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