Sciencemadness Discussion Board

How/Where to start for the compressed-gas-naive?

Yell0wJ4cket - 12-5-2022 at 22:37

Being over the use of a gas-generator after only one use, I've been trying to figure what is needed for this area, and am at wit's end (which takes less and less nowadays). I know I need a regulator of some sort and a "needle valve" if I want a steady flow rate at varying fill levels in the cylinder, but that's about the extent of what I've understood after 2 weeks in google's libraries.

Because shipping compressed CO2 isn't legal(?), and every outlet locally that sells compressed gas wants to treat the process like it's B2B with the establishment of business relationships and plenty of paperwork just to buy a tank of N2 or CO2, I've started to look towards paintball CO2 as what was originally thought to be a convenient solution, but it brings it's own complications, such as: how the hell does one set it up, with it's pin valve already in place, for continuous flow and simple adjustments of said flow rate?

Tsjerk - 12-5-2022 at 23:02

Talking about legality without mentioning your location doesn't make sense.

Fantasma4500 - 12-5-2022 at 23:41

i have come across some very fancy CO2 extinguishers at an abandoned place, and at my old job we would get literally thousands of extinguishers in that went out of date, mainly powder but also many CO2
i have a couple times suggested freetime welders to simply get a CO2 fire extinguisher and plug onto their welding machine
in europe, buying pressurized oxygen wasnt a problem- sounds weird that CO2 would be a problem for you, they usually do rental but i was able to just buy one to keep private- theres size regulations for private ownership though. maybe look for some place that has firefighting exercises, and sneak an used fireextinguisher with you or maybe buy one, its worth zero to them when its empty. fill some dry ice into that. cryogenic fluids may be used to make your own dry ice, preferably with some CO2 forming reaction, and liquid nitrogen is oftenly used in the industry to shrink metal parts to fit into other parts

as for your use, if its just for plants yeast and sugar fermentation should do

Yell0wJ4cket - 13-5-2022 at 00:17

Quote: Originally posted by Tsjerk  
Talking about legality without mentioning your location doesn't make sense.


It was just an assumption, since nearly every listed item labelled "CO2 cylinder" or "CO2 tank" on the big auction site is sold empty, and the pursuit of filled-cylinders is suspiciously fraught with a lack of useful resultsand references to DOT code. USA here.

Primary use (at present) is a carrier/diluent/inert gas for use with a self-made tube furnace/catalyst tube; ketones from carboxylic acids. Since I've been curious about the use of dry CO2 in Grignard preps of carboxylic acids as a replacement for dry-ice, I figured CO2 gas the best one to choose.

Previously, a bicarbonate/acetic acid generator was used, but trying to balance the gas generation/flow rate by constant adjustment of the "CO2 acid" addition funnel simultaneously with the constant adjustment of the "ketonic acid" addition funnel is something that, while not the hardest job in the world, is certainly a nuisance that doesn't allow for even enough time to eat or use the restroom while operational.

[Edited on 13-5-2022 by Yell0wJ4cket]

[Edited on 13-5-2022 by Yell0wJ4cket]

[Edited on 13-5-2022 by Yell0wJ4cket]

draculic acid69 - 13-5-2022 at 02:05

Quote: Originally posted by Yell0wJ4cket  
Being over the use of a gas-generator after only one use, I've been trying to figure what is needed for this area, and am at wit's end (which takes less and less nowadays). I know I need a regulator of some sort and a "needle valve" if I want a steady flow rate at varying fill levels in the cylinder, but that's about the extent of what I've understood after 2 weeks in google's libraries.

Because shipping compressed CO2 isn't legal(?), and every outlet locally that sells compressed gas wants to treat the process like it's B2B with the establishment of business relationships and plenty of paperwork just to buy a tank of N2 or CO2, I've started to look towards paintball CO2 as what was originally thought to be a convenient solution, but it brings it's own complications, such as: how the hell does one set it up, with it's pin valve already in place, for continuous flow and simple adjustments of said flow rate?


Home brewing supply, restaurants,soft drink industry, welding supplies are where to look. Trying to get a full tank online sounds silly.

[Edited on 13-5-2022 by draculic acid69]

wg48temp9 - 13-5-2022 at 02:23

You can probably buy a sodastream bottle at big store.
You also find them, with the carbonating machine, at thrift stores.

You will need an adapter and ideally a regulator.

sodastCapture.JPG - 23kB

Yell0wJ4cket - 13-5-2022 at 06:16

Quote: Originally posted by draculic acid69  

Home brewing supply, restaurants,soft drink industry, welding supplies are where to look. Trying to get a full tank online sounds silly.

[Edited on 13-5-2022 by draculic acid69]


In a remote/rural area, 60+ miles to the nearest brick & mortar homebrew supply. I've checked different (online) shops related to homebrewing for N2 and CO2, the only welding supply around here locally doesn't have an online presence and would likely scoff at the notion. None of this would be an issue if the local businesses here were open past 6pm (not exaggerating) and my circadian rhythm was that of a religious farmer who doesn't believe in the evils of modern tech and excessive use of electricity's temptations.

I HAVE checked inventory of the local W-M online, and they claim to stock SodaStream refills, (as well as another brand that I can't remember the name of at the moment) but over the past 3 months and 5 visits, they're always out of stock.

This still raises the question of how to connect one of these pin-valve-equipped smaller alternatives (CO2 from paintball or countertop soda carbonators) appropriately for use with lab glassware and a steady, consistent flow rate of roughly "1 bubble per second" or less than 5mL/min. Is there anyone with firsthand experience using these more compact sources for lab purposes?

Edit: Must've overlooked the mention of CO2 fire extinguishers. I've unsuccessfully searched for them in the past when first attempting to track down dry-ice, but didn't exhaust all avenues in that pursuit so should revisit. Are there any tricks to rigging one up for a low flow rate and hands-free continuous flow?

[Edited on 13-5-2022 by Yell0wJ4cket]

[Edited on 13-5-2022 by Yell0wJ4cket]

SWIM - 13-5-2022 at 07:38

There may be ways to better control your acid generator. Yeah, I know you're sort of through with those, but if things don't pan out with the tank Idea there are a few possibilities.
And the dosing pump idea could apply to CO2 canisters too, in a sort of half-assed, but cheap way. (see last couple of paragraphs)

Like peristaltic dosing pumps, or other low volume pumps, either for finer control of the acid addition, or to control the rate the gas itself enters the furnace at.

CO2 is pretty cheap to generate so your generator could be set to make a lot more than you need and the gas could flow into a flask with a bubbler acting as a vent to maintain a CO2 atmosphere at just over atmospheric from which you could pump into your furnace through an appropriately sized peristaltic pump. There are cheap ones in various sizes on Ebay.

If you want to get all fancy and blow some cash you could try a couple of constant addition funnels. These would be like $50 -$60 each delivered depending on where in the USA you are, but would also work for addition of all kinds of corrosive stuff and basically be like a very well-controlled version of the addition funnels you're probably using now.
They can be turned all the way down to 1 or 2 drops per minute and have a pretty constant rate regardless of how full they are.

Those funnels also have the advantage that they look really cool.

Regular addition funnels can be set up for a more or less constant flow rate as well if the variation in flow caused by the liquid level in the funnels is the main problem. It's just a clever venting trick that you don't see used often but I bet some of you older chemists and cooks would find it familiar if you saw it or maybe even know what I mean.

It involves venting the funnel through a tube in the top which goes to almost the bottom of the funnel so it vents gas into the funnel below the level of the liquid in the funnel. This requires either a non-pressure compensating funnel or one with a valve on the pressure compensating arm.

I kinda like the idea of using a peristaltic pump to pump the CO2 into the furnace from the generator.
Those little suckers act like positive displacement pumps, so one of the right size would be pretty simple and fail-safe as long as the generator produces at least enough gas to do the job. excess gas production would not be a problem.

Edit: just saw your latest post, which was made while I was rambling out my last post.
5 ml/min is a rate that you should be able to get cheap peristaltic dosing pumps for on ebay. Like $10 or less. Some of the cheap ones come with different heads for different flow rates that can be swapped.
You could even use one to pump the gas from a balloon you filled from a soda stream tank or other pressurized sources.
I doubt they could handle pressures much over 10 PSI. But of course the pressure in the tank you fill that balloon with doesn't matter.


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WGTR - 13-5-2022 at 10:13

A weldor’s supply store is your best bet to buy/fill gas cylinders. They typically sell up to the half size (125cf?) cylinders to private individuals. If you are truly saying that you can’t get yourself up early enough in the day to make it to a store that closes at 6pm, then you’re on your own here.

Deathunter88 - 13-5-2022 at 14:43

USA is literally the easiest country to get compressed gas cylinders for the individual since there are so many hobby welders. Go to any welding store (Airgas for example) and you can rent a cyclinder for not a lot.

SWIM - 13-5-2022 at 18:18

Quote: Originally posted by WGTR  
A weldor’s supply store is your best bet to buy/fill gas cylinders. They typically sell up to the half size (125cf?) cylinders to private individuals. If you are truly saying that you can’t get yourself up early enough in the day to make it to a store that closes at 6pm, then you’re on your own here.


If you can't get up before they close, maybe you can just stay up until they open.
I've been there myself for reasons I won't elaborate on, but you might be able to guess:D

draculic acid69 - 14-5-2022 at 05:13

Quote: Originally posted by wg48temp9  
You can probably buy a sodastream bottle at big store.
You also find them, with the carbonating machine, at thrift stores.

You will need an adapter and ideally a regulator.



Trying to makeshift an adaptor and a regulator for a highly pressurized vessel would take major engineering know how to do properly.cheaper to just go to a hardware store or welding supplier and buy/rent a small tank.

Fantasma4500 - 15-5-2022 at 02:48

renting in my country costs about 0.5 dollars a day. multiply that by 365
"just go buy it" is a neverending haunting on this forum
to add salt to injury you didnt even bother reading the original post on this thread where he explains difficulty in even getting to rent compressed gas flasks

Rainwater - 18-5-2022 at 01:12

With limited access to the equipment normally used, may I suggest storing the gas inside of a balloon(for dry gas) or water tower so you can more easily control the flow rate

https://youtu.be/Cm46KAPLZpQ time index 5:45
https://youtu.be/5hfznunVzKY

This may also be useful
https://youtu.be/2cWa5ENWxAg

Herr Haber - 18-5-2022 at 08:51

Quote: Originally posted by Yell0wJ4cket  

This still raises the question of how to connect one of these pin-valve-equipped smaller alternatives (CO2 from paintball or countertop soda carbonators) appropriately for use with lab glassware and a steady, consistent flow rate of roughly "1 bubble per second" or less than 5mL/min. Is there anyone with firsthand experience using these more compact sources for lab purposes?


Not direct experience in doing what you want to do but actual experience in paintball.
Just ask your local club / refill station. Sometimes we had to change the type of valves so I'm certain they had too and will have first hand experience and probably find you parts if needed.
I wish I remembered more myself about different valves... I got 3 big N20 containers I picked up on the sidewalk that will be awesome steel containers for distillations.

Also, if your local B&M doesnt have an online presence why dont you just give them a call ?

WGTR - 18-5-2022 at 10:06

OK. Here is an idea for storing and metering various gasses:

https://www.sciencemadness.org/whisper/viewthread.php?tid=71...

It doesn't have to be implemented in this exact way. The idea is that there is a (large) container that is air-tight. A piece of tubing is sealed to a plastic bag, and the bag is stuff inside of the air-tight container. Air is supplied through another piece of tubing to the container, this causes the bag to collapse and force gas from the bag through the exit tube. This way the gas can be compressed a bit, but the two gas streams never mix. Also, a flow-meter can be used inline with the compressed air input. This is a handy option if the process gas is corrosive to the flow-meter components.

If you just want simple (mildly) compressed gas storage, then the gas can be stored in a bag, with the bag placed into a much larger (by volume) container. The greater the ratio between the container and bag volumes, the less pressure change between a full and empty gas bag.

If a gas being stored is fairly inert, then a bladder tank can be used:


pressure tank.jpg - 10kB

[Edited on 22-05-18 by WGTR]

Mateo_swe - 20-5-2022 at 11:23

CO2 and Argon is used for welding and gas flasks are easy to buy, i think they are even sold on ebay.
I bought my Argon flask for my TIG welder online with home delivery to the door.
A one time use 8L flask isnt so expensive but if you want a refillable flask they cost more but are cheaper to refill in the long run, especially if you use a lot.
Argon is a nice inert gas that can be used as a replacement gas in most nitrogen atmosphere reactions if that is what you are looking for.

Yell0wJ4cket - 28-5-2022 at 03:15

I THINK I've gotten the necessary stuff figured out for my needs, but wanted to pop in and relay info gathered during my time spent reading.

For anyone looking to use paintball or soda carbonator CO2, or are a complete newbie to compressed gases and needle valves and whathaveyou, communities dedicated to aquariums and aquacultures (?) (with living plants and fish, [many of whom use improvised CO2 bubbler setups at a comparable rate of flow (a couple bubbles per second)]) are great sources of information on both improvised/adapted CO2 sources as well as reviews on needle valves. I found myself visiting the same board time and time again (plantedtank [dot] net).

I also sent in an application to airgas and will be making the special trip to the nearest one, since overall it seemed the least painful option, even with the longer-distance being a factor. Now I can also have several other gases and dry ice delivered to my door for an extra fee.

I would like if someone who's confident in their understanding of basic gas cylinder setup could check over my choices here and let me know if all looks right or if there's an obvious mistake in choices made. If linking to the shops where I plan to buy the specified part(s) is against the rules, let me know and I'll remove the links.

Cylinder, regulator, needle valve, and adapter fittings for inline usage of needle valve; everything look right to the knowledgable here?

First off, 50lb Industrial-Grade CO2 (CGA320 thread) :
(Should guarantee that I don't have to make the trip out anytime soon)
@airgas

(Since airgas regulators are ridiculously high priced, around $500 USD, I opted to find a higher-rated option via a third-party for now.)

MrBrew CO2 Regulator, CGA320 threads, 5/16" barbed outlet, 4/5 Stars

Fabco NV-55 "Micro-Fine" Needle Valve :
(Highly praised in the aquarium scene, this will be used "in-line" so it is connected via the tubing and 2 barbed fittings instead of connecting to the regulator; inline seemed the obvious choice.) 10/32" threads.

Two adapters for 10/32" threads to 1/4" barbed fitting:
(Enables "inline" usage)


[Edited on 28-5-2022 by Yell0wJ4cket]

[Edited on 28-5-2022 by Yell0wJ4cket]