Any idea how I can fill a standard, airtight plastic storage box (45 litres) with Argon? The naive solution would probably to "pour" Argon into the box since it is heavier than air, but there must be a better way. Maybe punch two holes into the lid and place a valve in each one? If so, how would I install these valves without compromising the air-tightness of the box?

Any ideas are greatly appreciated. Also, please move my question to another board if this is not the right board; however, I couldn't find a better fit.

Edit: Follow-up-questions: IIRC winegrowers use candles to determine whether there is enough oxygen available to breathe in their cellars. What if I put an open box in a cellar deprived of oxygen, leave it there for a day and then put a lid on? Can I expect the box to be filled mostly with CO or CO2 or whatever is down there?

Edit 2: Consensus seems to favour the vacuum bag solution. Thank you for all the great answers so far!

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    Perhaps some background on why you're trying to achieve this would be helpful – Drew Aug 22 '18 at 17:27
  • @Drew Don't know if "self-promotion" is allowed, but this is the follow-up to a question I asked on the lifehacks stackexchange. Basically, I want to store my "stuff" away and while storing everything in plastic boxes in a safe and dry environment is certainly a good option, I thought about giving it this extra "twist" and filling the boxes with Argon to (1) prevent any chemical reactions from happening and (2) stop the spread of pests (moths, ...). – kratom_sandwich Aug 22 '18 at 17:31
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    If you have an airtight box, why are you worried about pests? Also, if the main goal is oxygen displacement, you could also consider CO2 or nitrogen, which would probably be significantly cheaper than argon. – kgutwin Aug 22 '18 at 17:38
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    Have you considered, rather than attempting to fill the container with an inert gas, using a vacuum container and evacuating the air from it? There are already consumer-grade means for this. And pure nitrogen gas is very inert (being a triple-bonded diatom). – Chris M. Aug 22 '18 at 17:45
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    I should add that they also sell vacuum bags for storing clothes and other items like comforters and blankets. I think those ones just use a vacuum cleaner to draw the air out. – Chris M. Aug 22 '18 at 18:00

Does it have to be Argon? Carbon dioxide is inexpensive, easy to find, fairly inert, and does a great job of killing insect pests (which you mentioned as a goal in one of your comments).

The simplest way to introduce CO2 into a container is with dry ice. Simply place a small amount of dry ice in the bottom, add the stuff you want to store, then place the lid loosely on the container. After the dry ice has had time to sublime, seal the lid. If your stuff is vulnerable to damage from contact with dry ice, you can cover the dry ice with a small amount of insulating material.

WARNING: If you seal your container too soon, it may explode. So, please be careful to make sure the lid is loose until all of the dry ice has turned to gas.

Estimate how many cubic feet of air will be in the container after your stuff is added, double that figure to provide a generous safety margin, then divide by 8.3 to get the number of pounds of dry ice you'll need.

You can read more about this technique and how it can be used for grain storage at http://www.thefoodguys.com/dryice.html.

  • Will this introduce humidity through condensation? – kratom_sandwich Aug 23 '18 at 9:00
  • @throwaway312 No, in fact it will likely decrease the humidity. Since dry ice doesn't contain any water, any humidity would have to come from the original air in the container or from other contents added to the container. The original air will be displaced by the very dry CO2. If the stuff you're storing is starting out wet, though, you'll be in trouble no matter what kind of gas you use. – mrog Aug 23 '18 at 15:58
  • @throwaway312 I failed to point out that improperly stored dry ice can have water ice accumulation on the outside which could cause problems. The water ice comes from contact with moisture in the air. As long as you keep the dry ice in the bag until you're ready to use it, it should be fine. – mrog Aug 23 '18 at 16:02

Note: This was based on insufficient information. I had no idea what this was for, and based on the initial information I came up with a way to effectively fill an empty box (with a balloon as a liner) with argon. Since the actual use is for storage of items within that box, as opposed to some scientific experiment involving small items placed into the box through an airtight hole or similar usage, the balloon method is not too practical as placing the items inside an uninflated balloon would not be easy. But since the answer still has some potential use, I am leaving it on the page.

I think you are going to have problems doing that. I will assume for the moment that it is really airtight - many times things are "basically" airtight but not 100%.

Start off by a common similar situation - filling a balloon with helium.

Do you start with a balloon full of air and push out the air with helium? No, because that would be very hard to do. In fact, if you tried to do that, you would actually end up with either the helium going in but no air going out - and end up with a 2x pressure mix of helium and air, or you would have to figure out a way to get the helium (which is lighter than air) in while getting air - and only air - to go out. Despite the difference in weight, that would not be an easy thing to do.

What do you do instead? You take an empty balloon and fill it with helium. There is no air to push out, so this works just fine.

With a hard plastic container (like a typical storage box), that just won't work - trying to push in argon would be similar to pushing helium into an air-filled balloon.

But that gave me an idea:

  • Get a LARGE latex balloon or similar airtight very flexible material. Large enough that filled/expanded it can fill the entire box but that initially it is empty.
  • Cut a hole in the lid of the box. Put a valve in the hole (bicycle tire valve?) and seal around it well.
  • Attach the empty balloon to the inside of the lid.
  • Put the lid on the box and make sure it is not sealed well. This is to allow the gas outside the balloon to escape as the balloon expands.
  • Attach your argon supply (tank?) to the valve and fill 'er up.
  • Seal the lid well. The balloon will be the primary airtight enclosure but the box, provided it is truly airtight, will be a secondary enclosure.

If you want to have a mixture - e.g., argon + air, or argon + helium or hydrogen + oxygen (not recommended!), use the same setup and fill up first with one gas and then the other.

  • Thank you for your thoroughly answer; indeed, I was afraid that this is the verdict on my situation. To follow up on your explanation: Let's say I put two valves on the box, on for air that goes out and one for Argon that goes in. Given the volume of the box and the amount of gas that goes in, is there a way to approximate the distribution of gasses in the box? E.g.: After pumping 10L of Argon into a 10L box, the distribution of air / Argon should be approximately 50-50 or 20-80 or whatever? – kratom_sandwich Aug 22 '18 at 17:39
  • @throwaway312 should be is the key. There are fairly simple physics equations that would tell you how this works. But I would be wary of relying on those equations for a one-off creation using consumer-grade materials - and I realize that going to lab-grade materials will really up the cost. I'll add some more suggestions though. – manassehkatz Aug 22 '18 at 17:42
  • @throwaway312 Seeing the intended usage, I would actually go with the "put everything in a heavy duty bag and suck all the air out with a vacuum cleaner" method. Easy, inexpensive, tried & true. – manassehkatz Aug 22 '18 at 18:02
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    I know this has an accepted answer but, We do chamber welding on titanium at our plant for some special parts, normally we pump the air out using a small vacuum pump, about a year ago our pump died and we needed to make a part right away, we opened the valve on top of the chamber that normally allows air to equalize. After that we slowly filled the chamber. (Argon is the gas used). We may have wasted some gas but our welder was able to make the welds and said it worked as well as the vacuum and refill method. – Ed Beal Aug 22 '18 at 18:28

I would go with the vacuum storage solution. If you're really adamant about surrounding your items with an inert gas, use the vacuum solution to remove all air, then fill it back up with Nitrogen or CO2...much easier than any valve contraptions requiring gas displacement. Gases behave like fluids and adding one gas in won't just push the other one out, but rather there will be eddies and interference and lots of mixing. Yes overtime density will reseparate them but not really what you need

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