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Thread: Fog Screen

  1. #1
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    Default Fog Screen

    I saw one of these on the weekend, at Melbourne's "Federation Square".

    Interesting, although didn't look that flash coz the lights were on.

    Didn't look terribly complicated to build either....
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  2. #2
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    The description sounds a little confusing, it's made with only water but is completely dry, and you can stand beneath it without getting anything on your clothes.
    I've sent them an email for a price though.

    Jim

  3. #3
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    You know, Fred and I were talking about something like this the other day, and after reading the description on the web page I'm really starting to wonder... Hmmmmm...

    Fred was thinking about using those little ultrasonic fog generators to create a sheet of fog for a laser show. (Sort of a set-up-anywhere-scrim, if you will.) You've no doubt seen these tiny fog generators sitting in fountains and "Feng-Shui" gazing ponds... They use ordinary water as the working fluid, and they make a fog/haze that looks a lot like the classic "dry ice fog". It doesn't last very long, and if you put your hand in it you don't feel any moisture. (Like you would if it was a misting nozzle or something.) They are really cheap too - like 10-15 bucks or so, and most any novelty shop sells them.

    Anyway, Fred's idea was to gang 15 or 20 of these things togther in a shallow trough of water, and then mount a wide squirrel-cage blower about 6 feet above it. The blower would suck the fog up from the trough, creating a vertical wall of fog that was roughly as wide as the blower suction. Presumably the fog would dissapate as it passed through the blower, so the only area where you'd have fog would be in the rising sheet between the trough and the blower.

    At the time, I didn't think the ultrasonic fog generators would make a fog thick enough to work in an application like this, but now that I've seen that website I'm not so sure. It certainly sounds like the same sort of technology. (Using water as a fluid, delivering short-lived fog that doesn't make you feel wet when you touch it, etc...) Maybe they make larger units that would do the trick?

    Damn Fred - you might have been on to something there! Aijii - did you get a good look at the unit you saw in Melbourne? Could you tell what was making the fog? (Sounds like an experiment is in order here...)

    Adam

  4. #4
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    There are ready units available from china at about $10000. I've been looking into this before when I was looking for waterscreens. The secret of the screen is really in the honeycomb at the output. It's the same technology that is used in windtunnels to get a smooth windstream.

    I calculated that you need something like 20-30 of these foggers to get the amount of fog used in fogscreen. Look at the waterconsumtion and compare it to that of the small foggers.

    But have no fear, there are large foggers that could be used. Something like these Large fogger
    You know, I have one simple request. And that is to have sharks with frickin' laser beams attached to their heads!

  5. #5
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    I know that its definetly the ultrasonic fog/water thingies. I can't remember how i know, i read it somewhere.

    The units do indeed have a "honeycomb" grating on the underside. I'd say, the middle 10% of hte "honeycomb" was where the fog was getting blown out from. The 45% either side of this was just blowing air. There is a row of fans on the top on both the front and the back of the thing. Thats about all I could see.

    I'd say internally, there would be a section in the middle where the fog collects.... and the +ve pressure from the fans is divided between this section and the other sections. I think the other secret is to have stronger air currents either side of hte fog, to "trap it" in between. The fog was very narrow, way less than an inch deep IIRC.

    Another lasershow guy in melbourne has also created a fog screen, although it doesn't seem to work as well... maybe the pics are just bad ?

    What was funny was that there was a bit of a "breeze", so the fog screen was getting pushed forward. Looked pretty cool. Need a LOT of fans I'd say. I'd be willing to have a play with the idea though.
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    I dont know how relevant it is but in commercial refrigeration, the cabinets that are used in supermarkets have honeycomb filters at the top of the cabinet that blow downwards, that makes an air curtain which helps keep the cool air inside the cabinet.

    Jim

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    I have been looking at these for a while. Lets build one at the pre selem meet. I will by the parts.

  8. #8
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    I wonder which fog-screens came first, the "finnish" one from fogscreen.com or the chinese ones...
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  9. #9
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    Quote Originally Posted by JimBo
    I dont know how relevant it is but in commercial refrigeration, the cabinets that are used in supermarkets have honeycomb filters at the top of the cabinet that blow downwards, that makes an air curtain which helps keep the cool air inside the cabinet.
    Jimbo:

    Spot on! Those "air curtain" blowers are exactly what we were thinking of. I didn't know that they had a honeycomb filter on the outlet though. (I guess that helps keep the air flowing straight?)

    If you had one of those things blowing up, and one at the top sucking up, do you think the combination of the two would be enough to make it work?

    Paul: Do you have some of the ultrasonic fog generating things?

    Adam

  10. #10
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    nope.

    just need to let the fog "go" in the middle of the air curtain....
    Now proudly stocking and offering the best deals on laser-wave

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