Limiting Cryo-Jet plume

[whiteape]

Hi Folks,
I'm looking for the best way to reduce the size of a CO2 plume using either an inline valve or simply a lower PSI cylinder. What's happening is we are trying to create a smoke effect in a closed cylinder (about 33 cubic ft. of space) without leaving a residue on the interior wall. We tried the effect already with Unique Hazer but virtually constant cycling left too much residue. The current cycle is 1/min about 11hrs/day total triggers is 4500/wk for 4wks about 18,000 triggers.
Thanks

 

[Les]

An inline ball valve (make sure it's rated for cryogenics) might be your best bet, but note that you can also vary the flow using the valve on the tank. All cylinders carry a high PSI, the smaller cylinders just hold less, and with a much shorter useful effect. As an aside, I've had reliability issues with the smaller tanks, so we always go with a 50# tank minimum. One other "gotcha" is the fact that even a 50# tank will only get you about 1 minute max of constant effect (or about 30 "bursts"). Beyond that, it will still make a lot of noise but the effect may run clear.

For longer run time, you may want to see about using a dewar tank. They are actually lower pressure, but have a lot more volume. You'll definitely need to play around with the pressures. Co2 jets don't like giving a reliable effect at low pressures since it's that rapid escape that creates the desired effect. As far as residue, you should only get some ice/frost at the output nozzle, but that's about it. The 'fog' doesn't leave any traces behind.

For more in depth technical information regarding using cryo effects, their run times with any given tank, etc; there is a great supplier called Sigma Services that my company works with. They are very good resources.

 

[whiteape]

Thanks Les,
I'll let you know what happens after tomorrow. I've ordered a dewar and a 50# cylinder for prototyping. Gear and tech will be in the shop tomorrow and the we will see.
Thanks again.
CM