building dry ice fog machine

[godd2]

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??

[Van]

Somebody's not using their freind the search button!


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.

[cprted]

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.

[godd2]

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?

[godd2]

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.

[derekleffew]

Originally Posted by godd2

... 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.

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/s...2-million.html, http://www.controlbooth.com/forums/s...hine-tips.html, http://www.controlbooth.com/forums/s...-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.

Originally Posted by BillESC

...Back in the late 70's and early 80's,...We...built well over a thousand units... Our best machine was based on a 55 gallon drum and contained two 1500W 120V heater elements, a fixed galvanized basket, a domestic hot water pump and two 420cfm squirrel-cage fans. There were also three 4" PVC outlets. The machine could cover a 30' x 40' with three feet of fog in about 15 seconds.

[godd2]

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?

[BillESC]

Here's a 463 CFM squirrel cage fan

[gafftaper]

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?

[godd2]

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??