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Wanted to explore the size and dimensions of a cartridge which might hold around .1 grams of CO2? Answered

Hi everyone,

I wanted to know how small a cartridge (probably made of steel) could be. If I wanted it to store 0.1 or even 0.05 grams of CO2, how small could it practically be?

Could such a thing be made easily, do you think?

If I wanted to move away from the standard cylindrical shape of my cartridge, toward a whisky flask shape perhaps (something a bit flatter) how much more size would the cartridge have to be and would that be a lot more difficult and dangerous as a container?

I would be much obliged for any kind of input.



16 Replies

verence (author)2013-09-20

First: Why?

Second: At what environmental conditions (pressure, temperature, ...)?

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chrisdarroch (author)verence2013-09-20

Couldn't really elucidate on your first question except to say that I have an invention in mind which may have a use for such a cartridge.

As to your second question. Standard pressure and temperatures of

0 to 30 degrees centigrade, but if difficult would have to limit this temperature range to around 10 to 25 degrees centigrade.

By the way. Thanks for your interest in my question.


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verence (author)chrisdarroch2013-09-20

Standard temperature, so solid CO2 (aka dry ice) would be no option.

But still: Why? - or better: What do you want to achieve / what can you spend?
- Just a cheap simple prototype for personal fun?
- A proof of concept for the next everyone-needs-it with millions of venture capital to burn?

A standard CO2 cartridge (to fill bike tyres, whip up cream, power paint ball guns, fizzle up beer/soda/water) contains 12 to 16 g of CO2. (Google "CO2 cartridges" of see here  [not affiliated, just the first link I found]) While you could shrink the inner size of the cartridge to reduce the volume, you would still need the same wall thickness (not sure, how thick they are, but I'd guess 0.1-0.2mm).

Given the dimensions of the cartridges on the page above (ca. 89mm length x 21mm diameter) you could probably use something in the 9mm length x 6mm diameter range (just a rough estimation). Can you machine something that small? Can you fill a canister that small? Can you create a small enough release mechanism (valve) to release the gas when you need it?

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chrisdarroch (author)verence2013-09-20

Thanks for the reply. I understand that it can be somewhat annoying to be asked advice but not supplied with a full problem space. I hope that you can understand that if my idea was of any consequence then fully explaining it here would likely invalidate any patent I might consider.

I do believe in attempting to think through all of the development and deployment stages that an invention may encounter in one integral whole and this would naturally include the patenting stage.

I would expect that the cartridge was filled with CO2 in the form that all small cartridges are. I am aware of the many of the cartridges now available and have found them as small as 1 inch with a diameter of 0.375 containing 075 grams of CO2.

I would not embark on an invention if I didn't think that it would infold as a large scale product release and so I am looking at the second of your suggestions as in "proof of concept".

So the wall thickness would likely be the same for my proposed cartridge as it would for the larger 8 12 16 gram ones, you reckon?

The three questions you asked at the end of your post are all questions on my list after I find that a canister that small could exist without some law of physics or something preventing it's existence, but you are right to bring them up.

I would have hoped that an experienced manufacturing designer may be able to lend support in answering some or all of those questions, but if I had to consider them on my own and find solutions on at least how to manufacture and fill the component then I will have to get my thinking cap on.


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verence (author)chrisdarroch2013-09-20

Hello chrisdarroch,

I do understand that you had a spectacular, ground breaking idea that will change the way we live forever! Well okay, there's a wee bit of sarcasm here, but the idea may be important for you or maybe even for all of us, who knows?

To answer your question, yes, it does not matter how much gas you enclose, just the pressure demands for the strength of the enclosure. Of course for a very large containment, it would have to carry its own weight, but for that itsy-bitsy mass you want you would be on the safe side.

What I found with an quick Google-Fu:
"The density of dry ice is about 1.5 g/mL, so 1 cc is about 1.5 g CO2."

I did not check that source, because it sounds plausible (1cc [i.e.1ml] of water is 1g [btw. it's "l" for litre, not "L"] - while a CO2 molecule is heavier than H2O, it is less polar so that little buggers pack more densely)

So, for 0.1g of CO2 you will need a cube of roughly 5mm. The wall thickness should be good with 0.2mm (for a steel container, alumin[i]um may be good as well).

So the questions stand: Can you produce a container that small, fill a container that small and control the release from a container that small? (And of course, the most pressing question: What kind of society shaking invention did you have?)

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chrisdarroch (author)verence2013-09-20

I am not assuming that my idea is groundbreaking or will work or will change anything, however as far as I can imagine (which may not be far enough) this invention, if workable, has potential to be a large scale product, otherwise I wouldn't bother because my first criteria for invention is whether I think that given the existence of that product, would anyone want it, want to buy it and could I make it for a good enough price? And at all times I am returning to these questions with the expectation that I could be absolutely wrong on any or all of these feelings.

If I elongated the canister then I could make it thinner? As long as I maintain the wall thickness, in your view?

As far as manufacture and fill. I hadn't spent much time on that but had a passing thought that a single continuous tube perhaps constantly filled with liquid CO2 passes along then a heavy shaping and cutting head cuts a little piece of the pipe sealing some co2 within (except happening hundreds of times per minute). Just a vague thought.

I am aware that seals in a pressurised vessel would not be as simple as a crimp.Though the seal would only have to last for a max of around 3 months for the most part.

The release would not be as much of a problem and it may not need much regulation if any.

Anyhow. Must go sleep as it is 1.30 a.m. here in Edinburgh, Scotland. Thanks all for your input.

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verence (author)chrisdarroch2013-09-21

A sphere is the strongest structural shape, a round pipe is still quite good. That's why commercial CO2 canisters are formed how they are.

A sphere is also the shape with the best surface/volume ratio - or weight/content ratio. If you go for a pipe form, the container will weigh more than a spherical one. As you only need 0.1g of CO2, weight may or may not be a problem - can't say more without more details.

Try to give more details without revealing your invention. Do you have size constraints and/or weight constraints? "happening hundreds of times per minute" sounds like mass production, so money is probably a concern. Does it have to bee food safe, maybe even by a medical standard? What do you need the pressurized gas for? Chemical reaction, the mechanical force, shielding some material from air, cooling something? Will people take the container with them? That may give a problem, when they take it on a plane.  

Your endless pipe idea could work (though liquid CO2 exists only in a heigh pressure environment), but you would end with a pipe crimped shut at both ends. How to release the gas?

I'd recommend you go and build a prototype of your idea with readily available parts. Don't care for size, shape, looks etc. just check that your principle works. If it does work (and there is some money to make, i.e. you can sell either the idea or the product), you can go and patent the idea - it's the idea that gets patented, not a special design. Then you can try to sell the idea to a company or build your own company to produce the thing. You may skip the patent at all, but then make sure that people know you had the idea first. Keeping it secret is (after some point) the wrong way. Someone else may either get wind of your work or have the same idea all by them selves. If they go public - boom, it's their idea and you are the copy cat.

Liquid CO2 is tricky, see here.

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chrisdarroch (author)verence2013-09-22

Hi verence,

Apologies for a somewhat late reply.

I am aware that a sphere is the strongest structural shape

and why canisters are chosen for their practicality and

other optimal proporties of spheres.

I would rather not use a sphere but it is not out of the


I would rather have a flatter shape but I understand that

this may introduce size constraints and other potential

technicalities which might be less acceptable.

I am not sure what you mean by: "money is probably a

concern" unless you expect that such mass production would

normally mean that I would have to minimise unit cost.

I am looking to do this however.

You think that crimping metal tubing could contain the

pressure of co2? Over 800psi?

Can I confirm with you, your belief that the thickness of

current cartridges should be 0.1 or 0.2 mm of metal?

If, as you suggested, aluminium might be used, would that

have to be a thicker wall? (aluminium would be more easily


I could build a prototype quite easily, however the size

and form are optimal aspects in my view, for a

buyer/licensee to be interested in it's application and

given a large scale prototype, I do not believe I could

convince buyers that the idea is definitely scalable to an

acceptable degree without developing a prototype closer to

expected size and near guaranteeing a final size forma.

This is why, I need to confirm that certain central

components are even tenable, financially and physically and

of course in terms of likely producability.

A crucial component is the cartridge. I need to make it as

small as possible. It can be made from almost any material

(obviously with cost being a foremost concern) Looking to

make them for cents at most. Should be flatter optimally,

But tiny tiny tiny as possible.

Of all the questions I have to deal with in potential

development I have to tackle this one primarily.The other

questions are pointless without realising this question


I need to fill around 20ml of space and so have estimated

around 0.1 0r 0.05 grams of co2 do contain that.

There is some variablity here as I could alter the design

potentially to accomodate.

I understand your reference to secrecy but of course I

understand that there is a reason for non-disclosure


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mpilchfamily (author)2013-09-20

The reason a cylinder shape is used is due to it's strength. If you change the shape the side walls will have to be much thicker and the overall weight will increase. It wouldn't be easy or cheap to make. You would need an engineer to design it. Then you would need several prototypes made to be sent off for testing and certification. Once that is done you can start having them manufactured and chances are you will have to order quite a few for a manufacture to even consider producing them. It's not something you'll be able to get 1 or 2 made.

When working on an invention it's best to start simple and use standard parts to build your first few prototypes and proofs of concept. Once you know your basic idea is solid and the thing will work as you want it then you can start working on ascetics and look into manufacturing custom parts.

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Thank you for your input mpilchfamily.

I wanted to determine likelihood of such a cartridge being built as well as dimension which is important.

There are unlikely to be any standard parts I could use as that would answer my questions (ie the cartridge would already exist)

It is not a vital technical necessity at the moment, that the cylinder differ from standard in shape.

I know that much of the basic idea is likely workable, but the size of the cartridge is important (it is not so much an ascetic consideration) and I do not know how small such a thing could be.

What size do you think a cartridge could be to hold 0.1 or even 0.5 grams of CO2? At standard ambient temperature and pressure?

If I know what might be possible for cartridge dimension then I can work that into the design.


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What do you hope to achieve with such a low amount of CO2?

As mentioned by verence, standard cartridge sizes are 12 and 16 grams. I'm not sure if that is total weight of the cartridge or just how much CO2 is in there.

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There is also an 8g standard and as I mentioned, I found an 0.75 gram one. I think that the weight refers to the volume of CO2.

As I have mentioned, It may be unwise of me to explain the function of the CO2 any further.

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Sorry, I meant to say 0.1 or even 0.05 grams of CO2.

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bwrussell (author)2013-09-20

How much pressure do you need from the cartridge?

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chrisdarroch (author)bwrussell2013-09-20

Hi bwrussell,

I am not sure about this aspect. I could say "not too much" but that might sound naive, however I need to fill a chamber on release of the cartridge contents with only the pressure lets say of something like a rather tight foil balloon..

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chrisdarroch (author)bwrussell2013-09-20

Hi bwrussell,

I am not sure about this aspect. I could say "not too much" but that might sound naive, however I need to fill a chamber on release of the cartridge contents with only the pressure lets say of something like a rather tight foil balloon..

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