cryogenics and co2?

[JahJahwarrior]

Hey...I was thinking recently that using co2 to produce jets of smoke would be pretty simple, and reasonably safe. As long as you are a few feet from thenozzle, there should be no problems with freezing (I have a little bit of experience with liquid co2, from playing paintball. Once upon a time, I managed to get a valve stuck, venting co2 right onto my wrist. 3rd degree burn, biggest blister I've ever seen, and becuase it was on my wrist, for months afterwards the burnt area would bleed just a bit--everytime I'd flex my wrist, it'd crack the scab a bit. but if you are even a foot away, it shouldn't harm you, I'd think), and bulk tanks of co2 aren't that much to rent. Does anyone know much on them? I cannot find tons on google....has anyone used them? am I wrong about how safe they are? Can I build a system myself/has anyone here done it, or can I buy one cheaply?

Thanks!

[Mayhem]

Motley Crue had CO2 ‘smoke’ for their last tour and although I didn’t get a good look at the system, it seemed fairly simple in design. There were several “nozzles” across the front that were about 2” in diameter and 4” long. I’m guessing that the feed pipe was about 1/2.

During the gig I was side of stage and the CO2 jets were loud but also very effective. However, long duration blasts did result in hail falling down on the stage!

Unfortunately I never got to see how the system was controlled but I imagine that all the valves and couplers would have to be fairly large to reduce the risk of icing up.

All in all, a cool look but very noisy and definitely something that you do not want to be too close too.

[len]

http://www.effectsco.com/index3.htm is one place that makes CO2 jets, etc. They have a couple moving heads which are dmx controllable. The key to the system is the oxygen sensor. Even though CO2 won't do much damage to skin if the jets are far away, they can force all the oxygen out of a room, which is a bad thing. I've never worked with them, but they are cool looking in the video.

[Mayhem]

Originally Posted by len

Even though CO2 won't do much damage to skin if the jets are far away, they can force all the oxygen out of a room, which is a bad thing.

Excellent point and one that is of upmost importance. This is one reason that CO2 is very good in fire extinguishers.

Wonder if those little DMX units could find a function as a remote fire control unit. How cool would you look if you were to put out a stage fire from the comfort of the booth!

[koncept]

Originally Posted by Mayhem

Wonder if those little DMX units could find a function as a remote fire control unit. How cool would you look if you were to put out a stage fire from the comfort of the booth!

that would be amazing, but would probaly require large ammounts of co2 depending upon stage size and size of the fire. all in all i think it would be a very cool effect for theatre if you did not need to worry about actors being injured by it.

[JahJahwarrior]

Eh, should be easy enough to calculate and have a wide safety margin to keep enough oxygen in the room. Plus, a few doors culd be opened and fans put in place before hand to circulate. I've got a chem teacher who might could help me figure out how to make sure we keep o2 in the room

[Radman]

Hehe or the actors could wear SCBAs (SCUBA minus the underwater) hehe I bet the costumer would love figuring out how to hide that under the costume... :D

[koncept]

if you do get to use these, please take pictures and post comments. i would be very interested in thier performance. I think it is safe so long as actors are not directly breathing the streams in.

[len]

The only place I've seen them used is in nightclubs, but that's probably because I don't go to the theatre as much as I'm in nightclubs. There is also a nitrogen system that chills the air. It's pretty intense.

[MHSTech]

Originally Posted by Mayhem

Wonder if those little DMX units could find a function as a remote fire control unit.

If you can get DMX to control a servo motor...we're in business.

Just as long as the working area doesn't reach over 426 PPM of Co2, you're good. I may be wrong, but I believe 426 PPM is the most Co2 you can take without getting poisoned.