Fog from 30 feet above stage.

[LXkat]

I am looking for suggestions regarding Fog machines. The creative team are hoping to have fog falling from the top of a drop to pool on the floor level, about 30 feet down. Only needs to be about 6 foot wide, but I am unsure of how to accomplish this effect. Not wanting to use dry ice, as this can get messy and hard to operate from a batten above the drop. We have an F-100 and looked into adding a rosco cold flow to it.
Has anyone ever made a fall f fog from a height like this? What did you do?
Any suggestions?

 

[Mac Hosehead]

It sounds like you need something like this:
http://www.reelefx.com/index.php?c=effect.view&id=126

The problem I might see with the chilled F-100 smoke is that if the smoke heats up on the way down it will start to drift anywhere the air currents will take it. How about a 30' hose down to a dry ice machine at stage level? The dry machine would need a builtin fan.

 

[TheaterEd]

I love working with this unit, but have never tried to get it to drop that distance. It's great for low lying fog without needing dry ice.

 

[sk8rsdad]

I think you're going to have to consider cryogenic fogs like a jet to get it to fall 30' and pool on the stage. We have a couple of the Antari ice units in our theatre and I highly doubt (pun intended) that chilled smoke will behave as you want.

 

[MNicolai]

I don't think you'll get the output from that F-100 that you would need for this, nor the chilling from the Coldflow. To make this effective you need to generate a lot of output and chill it way down so once it comes out of the spigots it stays cold enough to continue dropping all the way to the floor. If you don't chill it enough, it'll make it down 10' or so before just hanging in the air like regular fog/haze.

You may find these drawings useful, which describe what it takes to pump the from a G3000 using probably Molecular fluid through an LSG chiller. The chiller is driven off of a large dewars of liquid CO2 you would rent from Airgas or Praxair. FWIW, the chiller mechanism is very loud and you would probably have to put a sound absorptive fence around it leaving enough room for air intake, and maybe play some sound effects over it to avoid hearing it distinctly during a play.

 

[Van]

I'll echo what the others have said. A water based fog ain't gonna cut it. I see the only real option, for a drop that high, will be a Liquid Nitrogen system; even that may not make it 30'. Fighting ambient heat and air flow is going to be a killer.

 

[bobgaggle]

Don't know your show or design, but this may be a situation where projections and live fx can marry really well...