Making a smoke machine forcefully blast out the smoke.

[sanddrag]

I need to somehow make a small smoke machine give a powerful blast of smoke rather than the mediocre flow it has coming right out of it.

I thought I had the perfect system designed. You have your smoke machine. Right after it you have a sprinkler valve we'll call valve A. Then you have a little bit of line (hose/pipe) and then a T with a compressed air line coming into it. On the compressed air line you have a sprinkler valve B. Then coming out of the other inline part of the T you have a long length of line and then at the very end, a final sprinkler valve C. To emphasize, the compressed air and valve B are in between valve A and C.

To "fire" it, you would first keep valves C and B closed and valve A open. You would then produce smoke from the smoke machine and fill the line. When the line is filled with smoke, you would close valve A and open valve B to let in compressed air. You would wait about half a second for some pressure to build, and then open valve C to release a "blast" of smoke.

Well, I tried it and all I was able to do was make a pretty effective fog horn. The problem is this: the sprinkler valves take a miniumum of 10 or 15 psi to operate which the smoke sure as heck isn't going to be able to produce on its own. So, the smoke was never getting past valve A whether the valve was open or not.

What I'm trying to avoid is putting back pressure on the nozzle of the smoke machine. But any one way valve I believe is going to have a minimum operating pressure. Is there any sort of commonly available solenoid valve that is free flowing straight through and requires no minimum pressure?

If any of you have any ideas, please post them before 9AM Pacific time tomorrow. I need to build this thing tomorrow. I am open to other ideas, but I'm not going to hunt down anything that's not commonly available at a hardware store and I'm looking at a budget of maybe $100 max when it is done (including valves excluding a compressor).

Thanks so much.

Ever seen the design for an air-zooka? It would probably work to have your fog machine pump air into one of those, with some sort of large flap on the front, and fire it when you want to let loose a ball of smoke.

Another way to make that with household supplies would be to make a mini version of the firing mechanism of the airzooka ont he end of a bucket, and have the fog machine empty into there.

[Al Skierkiewicz]

Sanddrag,
Try dumping the smoke into a larger volume like an old bellows. Then you just presurize or squeeze the volume down to make the puff. Maybe a drum with a piston inside that you pull up to puff. I am assuming you are shooting for a "dragon breath" kind of effect. Compressed CO2 produces a nice effect, like from a fire extinguisher, too. If you already have compressed air, you may be able to use the first idea with the compressed air in a venturi type of vacuum that pulls the smoke out of the storage container. It might work but give significant turbulence.

[Steve W]

Things to remember:

1 - the fog machine must have unrestricted nozzle to allow it to work. If you cover the out put end and don't allow for outside air to mix with the fog, it won't work.

2 - The fog machine works with heated fluid. Any compressed air that is forced to mix will cool the fluid and cause it to liquid form faster, thus losing the fog effect.

3 - You could probably rent 2 or 3 units for $100.00 and give yourself more fog than you need.

As we are not sure of the use it is tough to come up with other suggestions. The old dump the dry ice fog might work if you have a large enough storage device.

[Mike AA]

Could you use some of the FIRST valves os your valves and plug the unused ports?

-Mike

[greencactus3]

Originally Posted by Mike AA

Could you use some of the FIRST valves os your valves and plug the unused ports?

-Mike

the FIRST valves are probably too small to use for this. for compressed air it lets air flow decently. but for a big "wad" of foggy air to go by... its a bottleneck. no need to be completeyl sealed like that. i think an "airzooka" with a big barrel might be the best way.

[lukevanoort]

Why don't you just feed the compressor from the fog machine, or a combination of the fog machine and atmosphere? I don't know what fog machines use to make fog, so please forgive me if this is a stupid idea because it'll destroy the compressor, or such.

[billbo911]

Originally Posted by lukevanoort

I don't know what fog machines use to make fog, so please forgive me if this is a stupid idea because it'll destroy the compressor, or such.

That is something I can actually help out with. There are two basic ways that "fog machines" operate. One is actually a smoke machine, the other is closer to a fog machine, but is actually a carbon dioxide ventilator.
The smoke generators use a heated chamber that has an oil based liquid injected into them. The resulting smoke is allowed to vent through a small jet or hole in the end of the machine. The rapid expansion of the smoke within the chamber is what forces it out the vent hole. This type of "fog machine" is usually used to permeate the air with smoke that has a fog like appearance. You can easily identify when this type fog machine is in use because the smoke usually has a fragrance associated with it, cherry is common, coconut is another variation. This "fog" usually appears suspended in the air.

The other type of "fog machine" usually makes use of dry ice as it's source of carbon dioxide. Honestly, I do not know what process is used to cause the dry ice to evaporate quickly enough to generate the blanket of "fog" that hugs the ground, or stage, that this type of machine generates.

[Steve W]

Originally Posted by billbo911

The other type of "fog machine" usually makes use of dry ice as it's source of carbon dioxide. Honestly, I do not know what process is used to cause the dry ice to evaporate quickly enough to generate the blanket of "fog" that hugs the ground, or stage, that this type of machine generates.

It is done by submersing the dry ice in hot water. This causes a rapid change in state that allows for a lot of "fog" to roll onto the stage in a short period of time.

[Al Skierkiewicz]

Originally Posted by lukevanoort

Why don't you just feed the compressor from the fog machine, or a combination of the fog machine and atmosphere? I don't know what fog machines use to make fog, so please forgive me if this is a stupid idea because it'll destroy the compressor, or such.

As the above discussions mentioned, the oil type suspends particles in the air. (It is pretty cool when you see the first time but after the fiftieth it kind of wears on you.) The oil particles would be filtered out by the compressor intake filter. The dry ice type dissipates as it reaches temperature (the melting point of the frozen moisture particles) As the fog/air passes into the compresoor it's temperature skyrockets leaving you with hot but moist air.

[sanddrag]

The right way to do this I believe would be with liquid nitrogen, but the special hoses, fittings, and valves that won't freeze up I hear are quite expensive. The smoke machine doesn't look like it is going toi work out. It seems like if it is confined at all, it just turns back into an oil and makes a big mess. So, no smoke this time I guess.

[ChrisH]

Originally Posted by sanddrag

The right way to do this I believe would be with liquid nitrogen, but the special hoses, fittings, and valves that won't freeze up I hear are quite expensive. The smoke machine doesn't look like it is going toi work out. It seems like if it is confined at all, it just turns back into an oil and makes a big mess. So, no smoke this time I guess.

At work we deal with LN2 all the time. While choosing appropriate materials is required, I don't think they are all that expensive. Of course I work in Aerospace and not on a student budget. Our financial pain threshold is a little different. Flexible tubing of the sort you need runs between $5 and $10/ inch. But much of the run could be stiff pipe which would be much cheaper.

I will go look around our LN2 tanks and see what I can find out about manufacturers. Also it might be possible to rent a big dewar for storage. I know one of our suppliers used to do that for their N2 supply.

Don't give up yet! I hadn't thought about LN2 when you brought up the problem, but I think the pressure relief on our systems has about the effect you want.

ChrisH

[sanddrag]

But here's the question now. Even if we could get a dewer of LN2 and a solenoid valve and some line and some fittings, would it be practicle and safe to mount it 15-20 feet above the ground in the moving head of a dragon. Or would we mount it closer to ground level and run a flexible line all the way up? ($$) Also, would it freeze all the flowers if it blew back on them? (yes this is for the tournament of roses)

Can you get LN2 from Airgas that is high pressure or whatever so when you relieve it, it comes blasting out?

Also, the system would have to remain in there, and probably filled too (unless we can install a filling valve) from now all the way until after the end of the parade.

[Alan Anderson]

Originally Posted by sanddrag

But here's the question now. Even if we could get a dewer of LN2 and a solenoid valve and some line and some fittings, would it be practicle and safe to mount it 15-20 feet above the ground in the moving head of a dragon. Or would we mount it closer to ground level and run a flexible line all the way up? ($$) Also, would it freeze all the flowers if it blew back on them? (yes this is for the tournament of roses)

It sounds like a blast of CO2 will have the effect you want. You might be able to replace the existing hose on a fire extinguisher with a longer one and have someone squeeze the trigger/handle manually.

Of course, dragons are supposed to belch fire, not snow.

[lukevanoort]

Originally Posted by Alan Anderson

Of course, dragons are supposed to belch fire, not snow.

Oooh, how about N2O? You'd get the fog effect with the ability to do fire effects too. Or how about a big tea kettle? It's ghetto, it's not explosive, and it's not hazerdously cold.