Compress helium in a CO2 cartridge

[lfin]

TL;DR Summary

Is it possible to compress enough helium in co2 cartridge to fill a party balloon, or even something more?

Sadly my physics knowledge has rusted since high school, and i'm struggling to find an answer to my question.
would it be possible to compress helium in a standard 12g co2 cartridge? would it be possible to compress enough gas to fill a balloon?
If compressing any helium in a cartridge is possible at all, how much lifting capacity could it have?

I can't really find any helium filled cartridges as such on the market, and I found mentioned that the pressure required to compress helium is quite high, so it may exceed the cartridge pressure rating?
Could someone enlighten me on the subject and break down concepts as simply as possible?
Thanks

 

[russ_watters]

I would think you can Google the volume of uncompressed CO2 in a cartridge or the pressure and volume and go from there.

But are you saying you actually want to compress the helium yourself, to fill the cartridge? That's unlikely.

 

[Baluncore]

The molecular weight of CO₂ is 44 g/mole.
The molecular weight of He is 4 g/mole.
The same number of moles will fill the same volume at the same pressure.

12 g of CO₂, will have the same PV as; 12 * 4 / 44 = 1.09 g of He.

One mole of gas, at 20°C and 1 atm, has a volume of about 24 litres.
So the cartridge will hold about 24 * 1.09 / 4 = 6.5 litres of He gas for the balloon.

 

[phyzguy]

I don't think this is correct. The CO2 in a CO2 cartridge is liquid.

 

[Baluncore]

The CO2 in a CO2 cartridge is liquid.

Well spotted.
CO₂ is liquid at 73 atm and 31 °C.
Critical point of CO₂ = 7.38 MPa, at 31.1 °C
Density of liquid CO₂ is 0.771 g/cc, (at 20°C).
12 g of CO2 liquid has a volume of 12 / 0.771 = 15.56 cc.
So we assume volume of cartridge is 15.56 cc.
What quantity of He gas can be compressed into 15.56 cc at 73 atm ?
Pressure ratio is 73. Volume is 15.56 cc.
73 * 15.56 cc = 1135 cc = 1.135 litre.

 

[lfin]

thanks for all your replies.
So from the last answer it looks that only about 1 litre can be compressed in a cartridge, so not very useful at all, as as far i can understand, that could only lift less than a gram.

I was trying to figure out if it was possible to build a inflatable personal beacon for signalling/ rescue, but it looks unpractical at best..
it looks that the other alternative may be to use hydrogen, but it would be too dangerous for the average person to use.

I wasn't looking to compress the helium myself, but to find someone who would do it commercially.

 

[Flyboy]

thanks for all your replies.
So from the last answer it looks that only about 1 litre can be compressed in a cartridge, so not very useful at all, as as far i can understand, that could only lift less than a gram.

I was trying to figure out if it was possible to build a inflatable personal beacon for signalling/ rescue, but it looks unpractical at best..

Let's not discard it out of hand just yet. There's definitely some challenges here, but they're still worth looking at from a thought experiment/learning opportunity perspective.

Issue #1: Sealing the cartridge. Every CO₂ cartridge I've ever seen has a puncture disc as the seal. It's a single-shot option that works quite well. No moving parts to leak or fail, so it's great for extended storage. But it does make recharging the cartridge impractical. Any helium cartridge would not be able to make use of that kind of a system, unfortunately, as they seal the CO₂ cartridge at ambient pressure using dry ice pellets in the cartridge. So you'll need a valve system, or an alternate means of charging the cartridge. For your particular case, it will also need to be able to be triggered without needing to turn a valve multiple rotations, correct? That will also add to the challenge.
So, what could be your options to do this?

Issue #2: Pressure. As others have pointed out upthread, running at standard CO₂ cartridge pressures doesn't provide enough helium for a practical balloon. Unfortunately, the kinds of pressures needed to fit a reasonable amount of helium is going to be more than twice that of the cartridge, which will absolutely burst the cartridge casing. You'll need to have a dedicated cylinder to handle that. Probably a composite overwrapped cylinder for weight savings. I know from first-hand experience that bottles like that can fit 88 cubic feet of oxygen gas at 1800psi, coming in at the size of a large handheld fire extinguisher... about 1 foot in diameter and 2 and a half feet long without regulator. They do have a 5 year inspection cycle, though. Something to keep in mind for your design.

Issue #3: Size. Do you know how much your beacon is going to weigh? That will help size your balloon, which then determines your gas volume that you need to store. Furthermore, is the lift gas canister intended to stay on the ground, or go aloft with the beacon? That weight would need to be accounted for if it's going aloft, too. Otherwise, it can stay on the ground and be your anchor weight.
How compact are you trying to make the assembled package?

it looks that the other alternative may be to use hydrogen, but it would be too dangerous for the average person to use.

Certainly an option, and a fairly valid one, actually. You'll get about double the lifting force out of hydrogen, from my understanding, and it should be noticeably cheaper, too.

The biggest issue would be leaks through whatever seals are used... molecular hydrogen is a slippery bastard, willing to straight up diffuse into and through certain metals. Helium isn't quite as bad, as it's not going to diffuse through the metal quite so aggressively, but it will absolutely slip through seals if not done extremely well.

I wasn't looking to compress the helium myself, but to find someone who would do it commercially.

Probably for the best. I've worked with 1800psi nitrogen and oxygen before, and it does require specialist equipment to reach those pressures, as well as care in setting things up, especially the oxygen. But that was on equipment designed for easy use, such as recharging the emergency oxygen on business jets and the emergency nitrogen bottle for the landing gear and brakes on same. I'm not familiar with helium or hydrogen handling, so that would require some research.

 

[lfin]

So the idea was to have a compact device that could be easily wearable, like a bulky bracelet, that would deploy a balloon with 10-50m line carrying a light and maybe a lightweight radar reflector.
The idea is to help rescue operations in remote location/sea.

Even with personal GPS beacons rescue can be difficult as the person can be hidden by vegetation, or waves, and the position could be still off by several meters, so having a flashing target that can be seen by people and radar as well could probably help speed up the 'last mile" rescue operations immensely.

Plus it would promote rescue operations by "bystanders" in the wilderness or at sea, as you don't need any special equipment to be informed of a person in distress that is relatively close (no need of radio-gps-satellite communications in case of someone deploys a PLB).

A flashing balloon in a valley or over the waves in your line of sight would be sufficient to trigger a call to rescue with precise info on the position, or for a boat to turn and head toward the target avoiding time consuming search grids, or the risk to loose sight of the person in choppy waves.
Plus no need of subscriptions, it would be a wear and forget item until it needs to be deployed.

So the idea was to design something portable like a bracelet or something that be clipped/integrated into backpacks and life jackets.

The size of a co2 cartridge would be ideal, because the whole thing would only consist of a small bottle, a striker/valve assembly, a small reel for a lightweight thread, and the ballon.
Led nowadays can be very small and lightweight and with some engineering the balloon could contain a collapsible mylar radar reflector, or it coul simply be attached below the ballon.

So the cartridge doesn't need to be rechargeable, and it needs to be an industrial product .
It needs to be a intrinsically safe product and foolproof (that would exclude hydrogen being flammable)
It needs to be light, carrying something the size of a small fire extinguisher is just impractical.

Diffusion of the gas through the balloon shouldn't be a huge issue, the balloon would probably need to stay afloat for a couple of day, max a week, there's probably no point to have it deployed for longer than that.

 

[Baluncore]

A radar reflector close to the surface would work at sea, but not in the clutter of forested hills. Flashing LEDs would need a more reliable power supply. An optically retro-reflective balloon would be easily visible by spotlight at night, and during the day, but not in a snowfield.

What is the lifetime of a balloon beacon, before it must be replaced, and will it still work when it is needed?

Will the package cover its investment, when compared to an emergency radio beacon with GPS, detectable from a satellite, an aircraft, or by a walker.

 

[bobob]

Just get a small cylinder of helium from a welding supply. You can ususlly rent the cylinder and helium is dirt cheap. Use that to fill whatever industrial quality container you can use (using a regulator, of course).

Alternatively. make your baloon out of a polyurethane coated fabric. Polyurethane coated fabrics are impenetrable by helium.

Don't use hydrogen. If you are not experienced using hydrogen, you could become a statistic.