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building dry ice fog machine

Discussion in 'Special Effects' started by godd2, Apr 27, 2009.

  1. godd2

    godd2 Member

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    hello....Next year my school is planning on doing Les Mis for the musical...therefore i am going to have to try to come up with some fog. Right now I am leaning on building 2 machines out of metal trash cans. I figure i need to make the lid sit on top more snuggly than normal but then build in escape valves so pressure doesnt build up.

    My question is on whether or not i need a fan unit inside it to make the fog come out better or but one on the end of tubing or what....

    I guess i want the fog to be able to shoot out kinda quickly to fill that stage.

    Ideas??
     
  2. Van

    Van CBMod CB Mods Premium Member

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    Somebody's not using their freind the search button!
    :mrgreen:

    There are multiple threads on here about construction of and implementation of Dry Ice fog machines. I suggest using a 55 or 35 gallon drum as opposed to a trash can but I guess a trash can would work. It's much easier to mount hot water heatre elements to a 55 gallon drum as it has flatter/ more planar sides.
     
  3. cprted

    cprted Active Member

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    How about renting a fog machine? Because I really think that is the way to go.

    1) You won't have to weld anything.
    2) Fog juice is much easier (and cheaper) to acquire than dry ice.
    3) Fog juice is much easier to store than dry ice.
    4) Fog juice is safer to handle.
    5) Fogger is easier to operate than the dry ice.
    6) You'll have more control and consistency with a fogger.
     
  4. godd2

    godd2 Member

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    will fog juice give you the same heavy look as well as not filling the air with fog? would i have to have some sort of chiller unit to make the fog stay down?
     
  5. godd2

    godd2 Member

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    i agree with the 55 gal drum but i am not sure where i would get one so thus trash cans...second i didnt see anyone else asking about a fan system so that is why i did ask...but maybe the fog just rolls out quickly....i dont know.
     
  6. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    The hose IS your escape valve. Yes, you need a fan, and a powerful one, usually a squirrel cage type mounted on the lid. Once the solid CO2 hits the hot water the pressure increases, then decreases rapidly after the initial burst, which is another benefit of pumping the hot water over the ice, rather than dropping it in a basket.

    As with all atmospheric effects, trial and error in the actual space, under performance conditions, is the only method for success.

    A couple of good threads: http://www.controlbooth.com/forums/special-f-x/10395-dry-ice-question-4-2-million.html, http://www.controlbooth.com/forums/special-f-x/9225-dry-ice-fog-machine-tips.html, http://www.controlbooth.com/forums/special-f-x/3555-liquid-nitrogen.html. Yes, we've covered the topic a lot, but always come to very few agreements as there are too many variables. Most agree that the Peasouper, AquaFog 3300, and LN2 are all good, but pricey, solutions. See also the glossary entries for the distinctions between fog, haze, and smoke.

     
    Last edited: Apr 27, 2009
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  7. godd2

    godd2 Member

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    i had read that entry but didnt really understand it but i think maybe i do now, so if i am correct i would put a water pump in the hot water at the bottm and then run it up onto the dry ice cage. so when the water pump is on, the fog is made. where is the exhaust tube come out then, above the ice or below?

    I still dont know what a squirrel cage fan is though....

    How loud are these fans?
     
    Last edited: Apr 27, 2009
  8. BillESC

    BillESC Well-Known Member Premium Member

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    Here's a 463 CFM squirrel cage fan

    [​IMG]
     
  9. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    I'm a little confused about your reason for making dry ice machines in the first place. I've seen the Les Mis official tour many times and it seems to me to use far more chemical fog than dry ice. I think there's a little dry ice in the prison scene and maybe some in the sewer scene. But the main point you want smoke is the battle and that's all done with chemical fog (and maybe some flash pots) no dry ice that I remember. You want smoke up in the air in the gun battle, not hugging the ground.

    Alex, when you did it did you use any dry ice?
     
  10. godd2

    godd2 Member

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    interesting..i honestly have never seen it on stage...my director told me we would need these so i have started working on it....we have a problem with fog machines since our fire detectors seem to be ultra sensitive....maybe the director is thinking we can avoid the particle problem with the detectors by using dry ice.....

    thanx for posting the squirel fan...does that go inside the barrel to suck gas into the tubing or outside in the gas tubing??
     
  11. icewolf08

    icewolf08 CBMod CB Mods

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    We didn't use any Dry Ice fog in the show at all. I could see possibly using it for Javert's Suicide as it can make a pretty decent looking river, but for the rest of the show it was pretty much just running two hazers almost all the time (just not in the indoors scenes).

    Consider this, the original Broadway production of Les Miserables is the show that spawned the Actors Equity Association (AEA) to start to look into possible health concerns with the use of chemical fog and haze. The original production used more chemical fog and haze than any other show to that date. I don't know offhand if/how they used dry ice, but I do know that AEA does not regulate it's use like chemical fog (because it stays low to the ground and you don't breathe it unless you are in it).

    On the other hand, since you are in school, you don't have to worry about AEA fog and haze guidelines, so you can run as much fog and haze as you want/can afford to. I have a feeling that the most beneficial effect for your show will be haze, and I would concentrate your funds/effort on either buying or renting a good hazer for your show. Not knowing how big your venue is, it is hard to make a great recommendation, but there are a lot of good machines out there. The Look Solutions, Unique2 is a great machine and very fluid efficient. The Le Maitre Radiance is very similar in characteristics to the Unique2. If you have the big bucks or a bigger space you might also consider the MDG Atmosphere. The Atmosphere requires a CO2 canister, so make sure that you know where you can get it filled if you choose to go this route.

    If you NEED the low fog look, dry ice is a good solution. However, and this may just be my opinion, I think that the show calls more for haze and fog than for low fog.

    Dry Ice is fun and building a machine can be fun and educational, however it requires a pretty big skill-set, proper tools, proper supervision (for the non-pros), and proper safety precautions. Lets just start with the well known tidbit: electricity and water don't mix well. One of the things that really gets brushed under the carpet in all the threads about making dry ice machines is the safety aspect. We are talking about working with 30-50 gallons of near boiling water, heated by electricity, on a stage with a dimming system. We are talking about then putting a dangerous compound capable of giving you near instantaneous frostbite into said water, causing the release of a dangerous gas. Anyone out there who is building their own dry ice machine, please make sure that you include appropriate fail-safe devices!
     
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  12. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    All good points, Alex, especially the safety concerns. To reiterate:
    The squirrel cage fan goes outside the barrel, usually mounted on the lid, and blows air into the drum, forcing the fog though the ducting an out onto stage.
     
  13. Les

    Les Well-Known Member Premium Member

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    We rented a haze machine for ours and ran it through the entire show.
     
    Last edited: Apr 28, 2009
  14. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    If I were you I would be talking to the local fire officials about disabling the smoke detectors in the theater and going on "fire watch". This is fairly common practice and will probably require you to have an off duty fireman on site. Then get yourself a hazer and go for it.

    Picture the scene in your mind: Here's a big gun battle, bang, boom, people die on the barricade, look at that gun fire, there goes Gavroche down, then Eponine... and here comes all the smoke from their guns, rolling down the barricade, crawling across the floor, and into the orchestra pit never more than 18" above the floor. :confused:

    Depending on where the characters die you might end up with their bodies disappearing in the pond of fog. AND you also have the possibility of them not being able to breathe for real once they are in that fog. Dry Ice fog has the nasty habit of displacing the Oxygen in the air around it... if you lay in it very long you may find yourself passing out or dead.
     
  15. BillESC

    BillESC Well-Known Member Premium Member

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    You would mount it to the lid of the drum to force air into the machine. The resulting pressure sends the fog out the tubes.

    Edit: Oops, didn't see the second page and the same answer already given.
     
    Last edited: Apr 28, 2009
  16. Van

    Van CBMod CB Mods Premium Member

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    went overboard. It's a quick an dirty SKP but it might answer most questions. Follow Dereks caveats. The electrical should only be done by a qualified individual. Sealing everything is incredibly important. Remember water weighs approx 8 pounds a gallon. Even a little weighs a lot.



    Ok I lied it's a jpg of an SKP. SKP's are being deemed invalid at the momment. I'll ask Dave if we can fix that.
     

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  17. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    Back to the original post. I question the safety of the garbage can. Seems to me metal garbage cans would be flimsy when loaded with the weight of all that water. I've seen some garbage cans where the bottom is only crimped into place not welded so it would leak. Plus you need to metal work and welding again doubt it can take that... get a steel drum. Won't cost much more and it wont crumple under the weight of 40 gallons of nearly boiling water.
     
  18. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Good point, [user]gafftaper[/user]. Many years ago in Chicago, I just looked in the yellow pages, went to an industrial part of town, and was able to buy used (but clean) 55-gal. drums for I think, $5 or $10 each. Today, a quick Google search shows one vendor has them new for ~$64.

    Edit: This just in. Some possibly (likely) pertinent information from the ESTA Standards Watch newsletter:
     
    Last edited: Apr 28, 2009
  19. Van

    Van CBMod CB Mods Premium Member

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    I have to agree with the Gaff and Derek, a 55 gal. drum is really the onlyway to go. A galvanized 35 gallon trashcan is usually only rolled together then hot dipped. Your only reall water seal is the zinc hot dip coating, which will deteriorate when exposed to water and the current induced by the heating elements plus the piping etc. I know that right next to the Penske place here in Portland is a 1 acre lot covered in 55 gallon drums all of which have been safely decommisioned and are ready to sell to the public.
    Be sure to know that the barrel you get is clean and safe to use. Nothing worse than starting to cut into a drum with a plasma cutter then read the sticker that say " racing fuel", 'couse then there is the other extreme where everytime we made fog it smelled like " Simulated Strawberry filling Concentrate".
     
  20. BillESC

    BillESC Well-Known Member Premium Member

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    When we were building fog machines we ordered our 55 gallon drums lined with an epoxy phenolic compound that prevented rust. Secondly we had a bung installed at the bottom of the side. A bung allows you to install a threaded valve to which you can attach a hose for draining.

    Instead of a plastic milk crate we used a galvanized wash tub (I forget which size, but one of them fits inside exactly and can be bolted in place.) We drilled a series of 1" holes in the bottom of the tub and lined the bottom with screen to prevent small bits of dry ice from falling through.

    Our "Fog-It Super" could hold 150 pounds of ice.
     

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