Concert sound/stage - what are these gas cylinders for?

I got restless last weekend and went to the Governor’s Ball at Citi Field in NYC mainly to see Big
Thief but Phoebe Bridgers played the next stage over right after Big Thief so I thought it would make a nice double bill and then I’d head out.

After the act before Big Thief, Pink Sweats, wrapped up (guess what, they all wore pink sweats) and the crowd cleared out I was able to get closer to the stage than I ever dreamed. I had to wait a while for Big Thief to set up and noticed all these gas cylinders between the subwoofers in front of the stage, then noticed more further back. What are they for?
https://i.imgur.com/FXmZEEL.jpg

Big Thief

https://i.imgur.com/AmnUHtm.jpg

I found it interesting that Adrianne Lenker, who does the heavy lifting, eschewed the ‘frontman’ position for a more equal position.

Did they have a pyrotechnics display?

No, but the band after them did (J Balvin). Some fire balls starting out from what I could see.

I suspect that’s your answer.
I couldn’t read the labels on the tanks, but they are probably acetylene. Which seems kind of dangerous, but does make huge balls of fire…

ETA: or maybe they are inert gas, used to pressurize some type of flammable liquid.

Here’s a super wild guess. Tanks with dark green shoulders indicate that they contain argon. Argon gas lasers are widely used for laser light shows. Where my connection is weak is that I have no idea if argon lasers of the kind they’d use need external pressurization or refilling.

Aye; I couldn’t quite make out the labels. Not sure why they were positioned between the subs and in front of the stage, tho; that seems like a precarious position. Those canisters aren’t anything I’d want attendees to be able to get their hands on easily.

Never seen a gas cylinder as a spectator of a concert. And I wouldn’t feel save If I did. This seems like a serious security risk.

I had some exposure to the industry 25 years ago and, even then, argon lasers were on the way out to make room for solid state YAG modules. They’re better in almost every way.

And, anyway, the argon stays in the laser tube, just like a neon lamp.

Well there you have it. That said, I still think those are argon tanks assuming the color is correct.

They did have a sturdy fence and several fit-looking fellows manning the space between the fence and the stage.

There were maybe 5 or 6 stacks of subs and batches of cylinders between the stacks, in addition to what was on stage. Whatever was in those cylinders there was a lot of it.

Argon isn’t flammable, and is heavier than air.

Kids, don’t try this at home, or anywhere else for that matter.

Could they be CO2 tanks for jets like this:

Aye; CO2 for a fog curtain was my first notion, but even then they are generally behind and under the stage so that techs can get to them in case of an emergency.

I like this theory a lot.

You’re right though, green normally indicates, if not argon specifically, another inert gas. Before I looked into it a bit ago after reading your comment, I’d have associated green with medical oxygen. It looks like there are different color codes for medical vs industrial or research cylinders but I can’t imagine needing either one in any significant quantity onstage.

Lasers (and relatedly, LEDs) have made incredible advancements in the last 30 years. DVD vs Bluray? Due to advancements in laser tech. Faster fiber optic? Similar advancements.

Here’s a full color system, turnkey for $2k:
https://x-laser.com/products/lasercube-wifi-by-wicked-lasers-2-5w?_pos=1
It includes software and the entire projector system (which moves the beam and changed color and blanks as needed) which used to be tens of thousands at least if you were lucky.

Here’s a bigger, club venue filling system for 2x $10, it would have been impossible 25 years ago and $100k 10 years ago. Note it’s turned down to 40% power:
https://old.reddit.com/r/lasers/comments/m8oqch/two_10w_units_from_kvant_in_a_dance_studio/

What I think of is some crackhead in the first row rushing to the bottles and opening every valve and causing maybe too much pressure in, well, something. I don’t know much about stage tech, but wouldn’t that be a concern?

That looks good. There was definitely a lot of smoke and fog effects.

Almost all concerts use fog/smoke/mist, especially indoors. It used to be when everyone smoked, they didn’t need them, but after smoking was banned in most indoor places, they realized their lights didn’t quite look right anymore.

I showed it to a friend of mine the other day but forgot to come back to the thread. He guessed compressed air for a confetti cannon.

You especially need them for lasers.

Usually but not always. If the audience is looking at where the beam terminates, fog or haze can be a distraction since they have to look through the visible beams to see the imagery on the screen or other surface. Often in these setups, the laser is the show. Like this for example:

But that’s not usually what entertainment lasers are going for. They’re usually performing beam effects where the bar of light moving through the air is the desired thing, frequently with other lighting.
You want the light to scatter and, like you said, particles in the air make that possible.

The laser system in that video is unreal for how much performance per dollar (or UK Pound, they’re not openly sold in the US) you get. Very impressive, their catalog page:
Shop the LaserCube WiFi, Pro, and Ultra Laser Light Show Projector