Dakota Instruments Precision Flowmeters - Ar, He, CO₂, O₂

[Oscar]

Just got these delivered. I plan on setting them up today as long as I can find enough of the 1/8" NPT→3/16" barb fittings. I paid ≈$240 for these shipped. Each one is about $56. For a hobbyist, heck of a lot cheaper to mix gases without a $1000+ gas mixer(s).

www.dakotainstruments.com

[ronsii]

Way cool!!!!

[Oscar]

I know what everyone is going to say, pressure this, pressure that, how will you control this, and that, blah, blah, blah, lol

Here is the setup





Here it is working. Repeatable consistent results, with each opening of the solenoid.

[Ingenuity]

Thanks for posting this. I have been curious about mixed gases. I am new to welding with gas, and was thinking I would go the mixer/s route, but had no idea they were that pricey @ $1000. I was trying to reduce the number of gas bottles I need, so just wanted 100% CO₂ and 100% Ar, and then "mix" to get C25 etc.

With your flow meter/s solution how do you achieve say C25? Adjust flow rates of each until you 3:1 ratio of flow (75% Ar:25% CO₂), assuming you do this based upon volume?

[Oscar]

Kind of sort of. I don't mix my own C25 because I have C25 tanks. I posted my spreadsheet-based Flowrate Conversion Calculator & Gas Mix Calculator in a separate thread. I tell the spreadsheet the desired final flowrate for the specific mixture, and it solves the equations I wrote and spits out the individual flowrates for each gas.

You can save your own copy as a Google Sheet if you use Google services, or you can download a copy as a Microsoft Excel. In either format, you can use either Google Sheets or Microsoft Excel app on your mobile phone to view/edit your own copy of the spreadsheet. I just added the cells/equations to give you individual flowrates for Ar/CO2 when you specify the final desired flowrate. (just don't mess with Sheet5 on the spreadsheet as that is the holding place for all the matrix equation solvers that calculate values).

Note for mixing your own C25, you'd need a CO2 flowmeter with a larger range than the one I got. You'd need the one with 15 CFH range to get up to a maximum of 60 CFH of C25, which should be plenty unless you're using a huuuuge nozzle with a 2" CTWD, lol.

Here is a screenshot of the cells I added for mixing C25




►Flow Rate Calculator Excel .xlxs◄

[John T]

Can we see the back side / connections.... ?

[Oscar]

Nothing fancy on the backside, just 1/8" NPT to 3/16" barbs for the gas hose that I'm using. Gas inputs on the bottom of the meter, outlets up on top. Them I tied the Ar, CO₂, and O₂ outlets into two Western 111 Y's like so (excuse the messy welds, I had painted it white only to realize I had it upside down after the fact, lol, so I just cut it apart and re-welded without cleaning much of the paint off )




The Helium is not connected since I'm not using it any time soon. But it's there just-in-case.




With this configuration, I can shut off any of the three gases, and do any binary Argon-based mix (C25 I don''t do since I have C25 tanks already; in this setup I'd be limited to 20CFH total flow since I can only dial in 5 CFH of CO₂ on that meter).

[davec]

Don't you need a check valve at the inlet of each Y tube? Otherwise if the cylinders are out of balance for pressure (and they probably always will be...) that gas could flow back into a line that has lower pressure? Perhaps your regs are stepping them down close enough to each other that it won't be an issue. Dunno, just wondering.

[Oscar]

Perhaps. They will be added. All regulators are set to 50 psi from the factory (I don't know how accurate that is), but I did order some basic check valves from Ebay so I can add them in-line to each hose at the outlet of each regulator. So far there have been no ill-effects.

[arcflash]

You should not need a check valve. The only way you will back flow is if the tank is empty. The gas is going to flow the path of least resistance which should be out the torch.

[Oscar]

You should not need a check valve. The only way you will back flow is if the tank is empty. The gas is going to flow the path of least resistance which should be out the torch.

I agree with you, but I still ordered some basic ones off eBay, as they won't hurt anything either.

[arcflash]

Have not had a problem doing it that way since 1973.

[Ingenuity]

Oscar:

Thanks for your spreadsheet and related info on this.

I came across the attached regulator/flowmeter (for two gases only) on Amazon for $65, incl delivery: https://www.amazon.com/dp/B07112PFVJ...xpY2s9dHJ1ZQ==





Would this work work my application of CO₂ and Ar gasses only?

Happy New Year.

[Oscar]

That's not what that flowmeter regular is for. That attaches to only one tank and has two output (of the same gas). Such would be the case for example when someone is welding stainless steel, and needs to purge the inside while still having argon going to the torch.

Argon flowmeter
CO2 Flowmeter

Those are the same exactly ones attached to my tanks upstream of the Dakota flowmeters. I just discard the adapter and the 5/8-18 nipple since I use 9/16-18 → 3/16" hose barbs that I get from my LWS for a direct hose connection. Western Enterprises 312-18, and 312-7 are the nipple/nut that go right onto my regulator. Those parts are meant for oxygen, but they seal up to 200psi, and they have worked just fine for me.

[Country Metals]

I have been thinking about this for a couple years. Makes no sense having 15 bottles when 4 works for everything. I like your regulators, perfect for mixing just a little short on the CFH like you said.



Sent from my SM-G960U using Tapatalk

[Oscar]

I have been thinking about this for a couple years. Makes no sense having 15 bottles when 4 works for everything. I like your regulators, perfect for mixing just a little short on the CFH like you said.



Sent from my SM-G960U using Tapatalk

Yea, I had contemplated something like this years ago, but I just barely got around to it. These regulators aren't short on the CFH as a product short-coming; the low-CFH capabilities were specifically chosen due to the resolution needed to dial in very small quantities. You can get them in any "scale" you want, up to and over 80CFH if you wanted. One acquaintance liked my setup so much, he has commissioned me to make him a dual-setup, for Argon-Helium for when he welds thick aluminum.

[Oscar]

Update.

The whole setup is still working, and with the pressure-reduction regulator, the whole-setup is even better, for me.

Right now I'm on the 3rd "Frankenmixer" build that I'm making for a customer in South Carolina, and just got commissioned to make a 4th one, just for Ar-He.

This is the 3rd one here that I'm working on. Strictly for MIG, with Argon, O₂, and dual CO₂ flowmeters.






Contact me if you would like one built for you to your specifications!

[Welder Dave]

When your making gas mixers and have different types of gases do you still qualify as a hobbyist?

[Oscar]

When your making gas mixers and have different types of gases do you still qualify as a hobbyist?

Why not? I'm not a professional welder, as I have full-time job. Think of it like an over-grown hobby.

[rexcormack]

Hi Oscar,
Really nice setup!
Are you sure that hose is rated for Oxygen service?

Rex

[Oscar]

No but it seems to be working fine.

[N2 Welding]

Interesting

[metalmagpie]

Great work, Oscar! I made up a gas mixer from individual flowmeters once just like you did. Here's a picture:



I convert all the flowmeter outputs to CGA-022 if needed, using a Western Enterprises adapter, part number AW-403. Then, I use oxygen check valves, also made by Western Enterprises (or others), part no. CV-32R. This assures that the shielding gas only flows out of the flowmeters, so no mixing can occur inside the cylinders, which would make your welding gas supplier very unhappy indeed! Then I use a simple 'Y' fitting, Western 101, and a pair of short hoses with CGA-022 compatible (oxygen) fittings to join the outputs of the flowmeters. Finally, I use a Western AW-28A to convert back to inert gas. Simple, eh? Here is a legend describing the items in the above photo:

NO. .....ITEM
1 .....CGA-022 (9/16-18RHM)
2 .....CGA-032 (5/8-18RHF)
3 .....Western AW-403
4 .....Western CV-32R
5 .....Western 101
6 .....Western AW-28A
7 .....CGA-580 nipple/nut

I don't use that setup any more, but when I did, it worked. I have a different setup now. I do have one practical tip: when you are using gas from multiple cylinders, be SURE to turn them all off afterwards! (ESPECIALLY if it's a helium cylinder!)

metalmagpie

[Oscar]

Nice setup.

[Oscar]

Finished the 3rd Frankenmixer. Headed out to South Carolina tomorrow.



Now to start on the 4th one.