Shielding Gas Mixing.....

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Hey guys,I'm kinda directing this thread to any of the members who mix their own shielding gas. I know SundownIII & I believe, Zapster, use them. My query is regarding the combination of gases that are/are not subject to mixing with a Smith Gas Mixer like the one I have listed below. The Smith data indicates (2) gasses such as AR/CO2, AR/O2, AR/He can be mixed with set proportions as to % needed. I bought one of these Smith mixers on a used equipment site that is in superb condition for less than $200. When I saw the price of a new one, I almost had a coronary. My main objective is to mix my own % of AR/O2/CO2/He to any combination if needed for something unusual. Is there any gas that would not be able to be used with the Smith mixer, such as Hydrogen? The reason I ask is because I believe the listing said it was used for AR/Hyd....not sure definitely. I did a lot of research of gasses & all indications were that it would not make a difference what the particular designation was(the one I got) even if it was different from what I want to mix. The primary concern dictated was that the mixer was setup with backflow valves so as not to bleed into a near empty or empty bottle that may cause issues with the original contents. I'll post the pics of it when it comes in. Thanks for any input.....DennyHere's the listing a new one I researched that is the same unit.....http://www.grainger.com/Grainger/SMI...ZP3?Pid=searchComplete Welding/Machine/Fab. ShopMobile UnitFinally retired*Moderator*"A man's word is his honor...without honor there is nothing.""Words are like bullets.... Once they leave your muzzle, you cannot get them back."
Reply:see link below (hobart forum) for discussion on mixers, including some revelations from Sundown IIIhttp://www.hobartwelders.com/weldtal...ad.php?t=33418Blackbird
Reply:yorkie,If that's the mixer you purchased, you will not have any problem mixing Ar/CO2 in any ratio from 100%Argon to 0%Argon, with the balance being CO2.Smith uses different orifices for different gases.  They are sized taking into account the specific gravity of each of the gases.My original/first Smith mixer was the model 299-011-1B which was designed for mixing Ar/Hydrogen.  After talking to the engineers at Smith, they gave me a formula where I could use my mixer for mixing Ar/O2.  The ranges on the display are no longer accurate.  Using the mixer in this way limited me to about 0-3% Oxygen in the mix.  This was fine, because I was primarily looking for a 98%Ar/2%O2 mix for spray arc welding.I later picked up two of the Smith 299-006-1B mixers which are designed for an Ar/CO2 mix.  I use one of the mixers for the Ar/CO2 and one for Ar/O2.  I now use the 299-011-1B for mixing Ar/Helium.My "main gas supply" for shop mig welding is the Thermco 3200.  Feeding that system is a 330 of Argon and a 50# cylinder of CO2.  I can go from straight Argon to straight CO2 or anywhere in between, with just a turn of the dial.  That unit supplies a 50' gas hose which has a Smith multigas flowtube (input pressure is set at 30 PSI) where I set my flowrate.  All my mig and tig welders have Western quick connects on them.With the High Capacity unit you purchased, I'd recommend you contact Smith Tech Support for recommendations for settings for the "non-designed for" gases.The only concern I would have for the High Capacity 2-Gas Mixer, is that it shows a flow rate of 20-700 SCFH.  You may have trouble dialing in a lower flow rate which would be applicable to a single user.  All my smaller Smith mixers have a flow rate of between 0-180 SCFH.You do realize that you need separate REGULATORS (not flowmeters) for each of your inert bottles or for your CO2 supply.  Cyberweld has the Smith regulators you need for about $100 ea.  Your LWS should be able to hook you up with the hoses you need.Hope that answered a few of your questions.  PM me if not.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Hey SundownIII,Thanks for your input..... & also thanks to Dave for the Hobart link.... good reading. I'll really give it a good going-over when it comes in & get in touch with tech-support at Smith. Since most of my applications will be with AR/CO2, I still want to be able to have other options available. I had a feeling there was an orifice parameter with flow & blend, just wanted to get any data to be sure I have it set up correctly. I know many don't need a mixer, although others may find this kind of information a good resource for future considerations, especially if setting up their own shop. I know that getting all the production runs I do, the mixer will make it more economical as I have several empty 330cf bottles waiting. Thanks again. Will post pics.....DennyComplete Welding/Machine/Fab. ShopMobile UnitFinally retired*Moderator*"A man's word is his honor...without honor there is nothing.""Words are like bullets.... Once they leave your muzzle, you cannot get them back."
Reply:Hey guys,Here's the pics of the Smith Gas Mixer I got from HGR Surplus in Ohio. When I opened the box, it looked like a new one....absolutely spotless. I'll post pics when I get it all set up.Denny Attached ImagesComplete Welding/Machine/Fab. ShopMobile UnitFinally retired*Moderator*"A man's word is his honor...without honor there is nothing.""Words are like bullets.... Once they leave your muzzle, you cannot get them back."