How much Dry Ice do I need?

[ipressgo]

I am currently working on a production where we will be using two Aquafog 3300 Dry Ice machines. If we are looking to have a continuous low lying fog effect for 10 minutes, how much dry ice should I purchase for each machine per show?

Thanks a lot in advance!

 

[Wolf]

Its going to be quite difficult to have this affect for a full 10 minutes, it will start out strong but after the first 4 minutes the out put is going to drop quite a bit. This is going to happen because the water will cool and there is nothing you can do about that... The longest i've had the dry ice run in these foggers is about 5 minutes and I used about 3/4 of a 5 gallon bucket. Im not sure how much actually was in the bucket since thats how we measure it after getting the shipment of about 500 pounds. A full bucket maybe weighs about 7-10 pounds.

 

[Parker]

I am currently working on a production where we will be using two Aquafog 3300 Dry Ice machines. If we are looking to have a continuous low lying fog effect for 10 minutes, how much dry ice should I purchase for each machine per show?

Thanks a lot in advance!

We just used the Aquafog 3300 at my space...
It is going to depend on a lot of factors:
1. How hot you get the water... there is a temp gauge that you can adjust (the hotter the water, the more density of fog you will get... it will also use up the ice faster)
2. How much air you are forcing from the fan, through the tube, onto the stage... there is a metal plate (with two thumb-screws) inside the top ice bin that you can adjust to get the appropriate level on the stage.
3. How the ice is packed into the bin... (now we are getting very picky)... some techs prefer to have the ice crushed into smaller pieces and some prefer larger "bricks" of ice with this machine.
4. How much air movement do you have in your theatre? The more movement will mean faster dissipation.
Unfortunately... the only real way to determine these factors is to "test-run" the equipment during the rehearsals... it can get pricey to keep testing it until you get it right.

Some general coments... 10 minutes of full fog will be a stretch for even the two machines. Be mindful of the condensation on the stage floor (or wherever the hose comes onto the set). Also... you can never have too many old towels on-hand when using these machines... keep an eye on the area around the machines as well (everytime you open the lid, it will dump some condensation from the hot water onto the stage). Please keep in mind that you are mixing some dangerous materials here... HOT water/COLD ice/DEADLY electricity... be safe and have fun!

 

[MPowers]

Quick answer. Pellets or crushed, LOTS of fog FAST. Solid block, not as much or as fast but much longer lasting. You can also regulate the fog during the gag by several methods, turning the pump on and off is the method that will conserve the dry ice and increase longevity. That said, each stage and set is a bit different, I can not tell you exactly how much but I would hazard a guess that you will need at least between 30 and 50 pounds per machine if you use block or large chunks and more if you use pellets. The machines will hold 75 lbs. First time the action sequence on stage during a rehearsal with no stops or "LINE". Do a trial test with a full 75, full set, no actors, try to keep the fog level (amount) where you want it. compare with your action timing. If you have dry Ice left, be ready with gloves and a scale, weigh what is left. If you don't have any left, go to plan B. If you machines are located where you can reload during the action, load machine 1 with max dry ice, machine 2 with about 2/3rds. When machine 2 is empty, refill while machine 1 continues. for eternal fog, simply repeat as needed. The only real way to tell is trial and error. Plan your trials well and limit the number of errors. It will cost $$$.

Michael Powers, Project Manager
ETCP Certified Rigger - Theatre
Central Lighting & Equipment Inc.
675 NE 45th Place, Des Moines, Iowa, 50313

 

[MercyTech]

You have an advantage of having two fog machines. I did a show where I needed a longer time span of fog, and I used the machines one overlapping the other. If one will cover enough of the stage by itself, you can try and run the first for several minutes, then add the second and reload the first to try and keep the effect going longer.

But the previous post mentions th e biggest problem I had, and that was the condensation. The floor got really slick and was a problem for the dancers.

 

[DJNickyB]

I use the LeMaitre PeaSouper and 20lbs of dry ice pellets lasts about 8 minutes ... When I check, there is plenty of dry ice in the basket but it's the water temperature that is the problem. Since you are looking for a continuous flow for about 10 minutes, you may want to run your machines serially (i.e. turn on the first for 5 mins, then the second when the first slows its output). An alternative would be to use a cryogenic unit but then you're talking big bucks.

 

[ipressgo]

Thank you everyone for your answers, and I apologize for taking so long to give an update. Naturally it's been a busy season.

We ended up using a bag an a half (which in our case is 41lbs) of sliced bricks of dry ice per machine to create the desired effect. Each machine was set at 160degrees and provided a continual thick covering over the stage for approximately twelve minutes.

The two key tricks for us: a) Sliced bricks allowed us to find a happy medium between a thick density and losing the ice too quickly. b) Waiting until the last possible second to dump the ice into the machine. We were able to find an applause break approximately 35seconds to the effect beginning.

Unfortunately trial and error is not always an option (especially when working in a union house where the producers will only pay for 8 hours of tech), and this is why ControlBooth is such an important resource in our profession.