Dry Ice quantitiy

[xllx]

I've got a job coming up in a few weeks where I am considering using a couple of Pea Soupers to do the classic dry ice over the stage look.

I've used pea soupers and dry ice plenty of times, but probably not in the last fifteen years!

 

I'm ok with storing, handling and using the product, just can't really remember how much dry ice I will need for my effect. Are there any good "rules of thumb" regarding quantity?

 

I will be covering a stage area roughly 16 feet x 8 feet. We need to keep an ankle deep cover for about 30 minutes, so the plan is to use two or possibly three pea soupers alternately to allow them time to reheat between batches of ice.

 

There will be the occasional person walking across the stage, so I would prefer not to use heavy smoke as I find that once disturbed it tends to rise and hang as a haze which is why I am planning to use old fashioned dry ice.

 

My dim memory suggests about 5kg of ice will give me about 5 mins of cover, is that realistic?

 

I appreciate that this might be a how long is a piece of string question!

[csg]

your 5mins / 5kg is pretty good - but continuous dry ice for 30 mins from pea soupers sounds really boring to me!

 

I appreciate noise may be an issue, but we have just taken delivery of a Look Solutions Cryo Fog unit which will give you 34mins from 1 full size bottle of Co2 at around £40 a go.

 

Much to our amazement, the output exhibits absolutely no rise or ambient hazing issues like most low foggers . The machine will run continuously - may be worth hunting out something similar from your local hire places. We are down in Luton so a bit of a drive, but possibly a much cheaper and more practical solution for the effect if you can find something similar locally.

 

If you are in the area, come in for a demo, and ill prove it does not rise etc...

[kitlane]

It's been a while since I've done this but are you sure the pea soupers will re-heat fast enough between 'shifts' if you have 3 of them?

[xllx]

It's been a while since I've done this but are you sure the pea soupers will re-heat fast enough between 'shifts' if you have 3 of them?

 

 

Likewise it's been a while here too!

 

I THINK I'll be ok with two machines, the possible third is just in case I'm wrong!

 

Anyone actually used Pea Soupers this century?

[Ynot]

Anyone actually used Pea Soupers this century?

Yep - we hve 2 in-house (though they're out in Liverpool with Blue Roomer IRW at the moment).

 

I've not actually tried to run them for lengthy periods, but from memory if they're producing fog for much more than 5 or 6 mins they WILL cool down enough to make the fog MUCH less efficient and what will happen when the water is not hot enough is the CO2 will begin to develop a layer of regular ice around the granules and that will impair the performance even more.

 

I have serious doubts whether you'll get a solid 30 minutes in a single run.

IF one machine will produce enough to cover your space, and I'd say a 16 x 8 foot space that's a fairly good chance, then running 2 machines in tandem MIGHT do you OK, but a third leap frogging them should do the job.

 

But no guarantees :)

[csg]

a trick that works for longer run time at lower output, but with less water cooling is to use big blocks or slices of ice - the bigger the pieces the smaller the contact area with the water, hence the longer run time / slower output. Probably needs a bit of experimentation for best results. To hire a londoner would be another option.

[xllx]

Anyone actually used Pea Soupers this century?

Yep - we hve 2 in-house (though they're out in Liverpool with Blue Roomer IRW at the moment).

 

I've not actually tried to run them for lengthy periods, but from memory if they're producing fog for much more than 5 or 6 mins they WILL cool down enough to make the fog MUCH less efficient and what will happen when the water is not hot enough is the CO2 will begin to develop a layer of regular ice around the granules and that will impair the performance even more.

 

I have serious doubts whether you'll get a solid 30 minutes in a single run.

IF one machine will produce enough to cover your space, and I'd say a 16 x 8 foot space that's a fairly good chance, then running 2 machines in tandem MIGHT do you OK, but a third leap frogging them should do the job.

 

But no guarantees :)

 

Yes, I'm not intending to run them all at the same time, I think five minutes or so per machine is about right. I think one at a time will be sufficient to cover the stage, and I'm hoping there is enough recycle time to keep the effect going by leapfrogging. One additional option is to have more boiling water on standby to top up if they are not reheating fast enough!

 

Might just be easier to go with heavy fog :-)

[Wizwam]

Just as a thought and if pennies will stretch but it will give you a firm solution to your quest.

http://www.mdgfog.com/en/ice-fog-compack

This unit will output long lasting dense fog which uses a 47 Litre Liquid Co2 (Air Products / BOC) feed which will last you the 30 mins non-stop (No stopping to re-heat required) Very low noise and no slippery surfaces.

Like I said, just a thought.

[xllx]

Just as a thought and if pennies will stretch but it will give you a firm solution to your quest.

http://www.mdgfog.com/en/ice-fog-compack

This unit will output long lasting dense fog which uses a 47 Litre Liquid Co2 (Air Products / BOC) feed which will last you the 30 mins non-stop (No stopping to re-heat required) Very low noise and no slippery surfaces.

Like I said, just a thought.

 

 

Slowly coming to the conclusion that something like this or the Look Solutions Cryo Fog will be the way I go. I'm just not sure if anything looks as good as proper old fashioned dry ice.

[alistermorton]

Slightly off topic, but how do the MDGFog and the CryoFog compare to the glaciator in terms of unit noise. I've only used a glaciator, and it hums hums away quite a bit.

[Wizwam]

Slightly off topic, but how do the MDGFog and the CryoFog compare to the glaciator in terms of unit noise. I've only used a glaciator, and it hums hums away quite a bit.

 

No humming from the MDG, you get a slight low rumble when Co2 enters the cooling chamber. You won't hear the fog machine part of it either. The liquid Co2 provides the chilling and output flow pressure, most of the noise is supressed within the cooling chamber.

Can't speak for the CryoFog. No idea.

[alistermorton]

Thanks - that's useful. We have limited wing space and getting the glaciator far enough from the acting area that it wasn't intrusive and the ducting wasn't in the way of entrances/exits/scene dock access etc was a problem.