Dry Ice Calculations

Hansentd

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May 31, 2015
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Metro Boston
Hi All,

Working on a haunted house-type event, and they'd like to have a large room with a low-lying fog.
I'm trying to figure out how much dry ice we'll need to purchase and how often we'll need to refill. We'd love to be able to set and forget it for a bit, not have it attended for the whole of the 4-hour event.

Is there a good calculation for how much vapor you get from a block (by size), or pellets (by weight, I guess)?

Obviously there are a lot of variables here- size of room, ambient temp, humidity, etc,etc,etc.

The room has a sunken floor area (actually stepped sides, but same difference)- so we have that on our side.
Any advice or anecdotes for making the effect last longer would be appreciated.
 

TimMc

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Feb 15, 2017
When Wicked! flew in for a month of shows I was the SL deck electrician and dumped about 150lbs of dry ice into a City Theatrical fogger every night. You can't put 150lbs into the bin, it wont fit and even if it did, it won't vaporize like smaller quantities do because that much dry ice chills the water too much.

You may end up with an MGD or similar fogger that has a chiller to keep the fog on the down low...
 

macsound

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Joined
Jun 15, 2018
Location
San Francisco, CA
In order for it to last 4 hours, you're looking at a fog chiller, not a dry ice machine.
Dry ice machines rely on the temperature differential between the cold dry ice quickly sublimating in the boiling hot water. Like Tim said, the dry ice will chill the water faster than the heater will heat it, leaving you with a large vat of cold carbonated water.
 

egilson1

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Feb 25, 2009
Location
Boston, MA
Take a look at the Chauvet Cloud 9. Non dry ice low laying fogger. Has a continuous run time of 2 hours. Not sure what you would have to do at the end of that time to get another 2 hours. 4wall Boston has them in rental inventory.
 
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