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  1. #1
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    Two tanks or dual out put flow meter for back purging?

    The regulator that I've been using for back purging is on its way out. Who is using a dual flow meter off a single tank? I was thinking of getting a Smith, or just replacing the single on my second tank with a Smith single.

    Are there any downfalls to a dual flow meter? It would be nice to have everything off one tank using the other as a spare so I never have to worry about running out completely.

  2. #2
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    Dual flow here

    Unless you already have a spare regulator sitting around, I think it's usually going to be better/cheaper to just run a dual-flow. If you do small jobs at remote sites and want a little tank around for mobility, that might be an added bonus, but the key is this: unless you can make sure you run dry on both tanks at the same time, you are going to be going to swap out tanks at the welding supply more often than you probably want.

    I get the biggest tank I can handle by myself so that I only have to go get a fresh one every 3-4 weeks, because it takes me 45 minutes or an hour to go do that, and I'd rather be hanging with the fam, riding, or doing work that I get paid for with that time.

    So IMO dual flow is the way to go.

    -Walt
    Waltworks Custom Bicycles
    Park City, UT USA
    www.waltworks.com
    waltworks.blogspot.com

  3. #3
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    Thanks Walt, this is the one I was looking at, local airgas quoted me about $170

    Smith® Dual Flowmeter/Regulator with Gas Hose Kit [SMI-33-50-580-GH] - $284.82 : Arc-Zone.com, The Welding Accessory Experts

    Do you have any particular ones that you like?

    I was hoping to find one with a slightly more accurate scale on one side (maybe a 0-10 cfh) but no such luck yet.

  4. #4
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    Looks good to me

    I have a Victor (appears to me to be identical to this: https://weldingsupply.com/cgi-bin/ei...EF:X:0781-1153) that I got about 8-9 years ago. It's been just fine over that time. I'm sure the Harris is good too.

    You don't need super fine scales in general, especially since you'll need to experiment anyway to see what flow rates work for you for different types of work. If you want to know the *exact* flow rates you can get a little gauge that actually measures at the torch, but I would not bother unless it's just inherently interesting to you. There are really only 3 levels you need to determine - too little, just right, too much. Once you know where on the gauge those are, you're golden.

    -Walt

    Quote Originally Posted by RCP FAB View Post
    Thanks Walt, this is the one I was looking at, local airgas quoted me about $170

    Smith® Dual Flowmeter/Regulator with Gas Hose Kit [SMI-33-50-580-GH] - $284.82 : Arc-Zone.com, The Welding Accessory Experts

    Do you have any particular ones that you like?

    I was hoping to find one with a slightly more accurate scale on one side (maybe a 0-10 cfh) but no such luck yet.
    Waltworks Custom Bicycles
    Park City, UT USA
    www.waltworks.com
    waltworks.blogspot.com

  5. #5
    DWF
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    Dual flow meter/regulator, Victor/MetalCraft. Mine's stamped DFM150FF. Smiths makes one too but the Victor is better at least from the perspective that the readings on both of the Victors site gauges face forward and on the Smith, one faces forward, the other backwards. I run one dual flow as above on two tanks daisy chained together....I just took a pic and posted it to my Flickr page....
    A man must have enemies and places he is not welcome. In the end we are not only defined by our friends but those against us.

  6. #6
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    Cool set up, I never thought about linking tanks. I will look into the Victor, thanks.

  7. #7
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    Quote Originally Posted by Walt View Post
    I get the biggest tank I can handle by myself so that I only have to go get a fresh one every 3-4 weeks,
    not to mention you get better pricing on gas with bigger tanks.

  8. #8
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    This is a timely thread for me. Trying to get up to speed with tig. Was thinking about the Harris 921DB double flow regulator here :

    http://www.rapidwelding.com/files/H1254.pdf (at the bottom).

    Can anyone confirm that this would do the job for setting up a regular shield gas with facility for back purging?

    Cheers

    Steven

  9. #9
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    Looks like it will work.

    As far as tank size goes, I have two 300's. They are as big as I would like to move by myself.

  10. #10
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    I have the Smith, and as Don said, the scales are a little weird. I just continued the Argon scale markings around the tube so that I could read them easier. $169.10 from Cyberweld with free shipping.
    Smith Dual Flowmeter Regulator - 30 Series

  11. #11
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    I will probably go with the Smith, just due to the fact that I am a creature of habit and once I find a brand that I like I have a hard time straying from it.

  12. #12
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    I took some pictures of my backpurge setup for Chris Dornbach awhile back. Here is the link if you are interested.
    Purge system Photos by zank1 | Photobucket

  13. #13
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    I love my Victor DFM150, it's dam simple. One tank, reach over to turn on/off. But I have accidentally left it on all night *twice* though...huge bummer. So I have wondered if anyone has heard of something that starts the backpurge as soon as you step on the pedal? I realize it wouldn't pre-purge all the tubes but you could have a separate smaller tank if wanted.

    Zank- nice setup! What is that Anvil-esqe purge hose splitter thingy? I have the want to get air hose fittings on my heat sinks that are easier to swap and have 90 deg angles like yours.

  14. #14
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    I'll get a parts list together for you.

  15. #15
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    Quote Originally Posted by zank View Post
    I'll get a parts list together for you.
    Thanks, but if you just sent me yours that'd probably be easiest

    If you're not being sarcastic, please don't bother listing the parts. Being inspired by your design to create something for/by myself is part if the fun!

  16. #16
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    Zank, that is a nice set up. I'd be interested in a parts list too if you put one together.

    Thanks,

    Alistair.

  17. #17
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    $170!? Ouch You can get a CGA580 "tee" and put a second regulator on it for less. I had a spare already, but you can get a cheap one for the backpurge if you don't already. Or consider upgrading to a "ball" style for your welder and move the cheaper dial type that always comes in the kits to the back purge side. Probably where my spare one came from.

    Edit: Hmm, the picture is uploaded but not showing? Can't get another picture to upload. Hmmmm. Here is a link to what one looks like on amazon (though its for a different gas type but looks the same):
    CGA590 Male/Female/Female Brass Tee - Amazon.com

    Edit2: Corrected the CGA # to 580 to be correct for argon tanks.
    Attached Images Attached Images  
    Last edited by smdubovsky; 01-20-2013 at 05:04 PM.

  18. #18
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    Quote Originally Posted by smdubovsky View Post
    $170!? Ouch You can get a CGA680 "tee" and put a second regulator on it for less. I had a spare already, but you can get a cheap one for the backpurge if you don't already. Or consider upgrading to a "ball" style for your welder and move the cheaper dial type that always comes in the kits to the back purge side. Probably where my spare one came from.
    I have a thread going on the Google framebuildrs list right now where I asked about using a splitter or a "T" junction for running a purge line.

    The response I got recommended against it, because it could result in a vacuum being formed that interferes with the Argon flow to the torch, which obviously could be a bad thing.

    Is there a way of setting things up in the way you're suggesting that will avoid that?

    Alistair.

  19. #19
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    I think he is suggesting "T-ing" the tank to 2 regulators.

  20. #20
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    Whaaaaat? There is full tank pressure in the Tee (up to 4500psi.) 10-15 cfm out of each regulator won't cause squat. The dual regulator just has the T built in. Fundamentally they are no different.

    Ball flowmeters measure actual flow (its whats pushing up the ball in the cone.) I see no difference in flow when I turn the back purge regulator on/off. If you were getting less flow to the torch, it would show.

    Ohhhhhhhh, it just dawned on me they are probably talking about a low pressure Tee *AFTER* one regulator. That is a problem. You don't know how much flow is going out which hose. You need the high pressure CGA Tee + 2 regulators for it to work right. Each flow needs to be independently regulated.

  21. #21
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    Quote Originally Posted by RCP FAB View Post
    I think he is suggesting "T-ing" the tank to 2 regulators.
    Right, but I am being told that that is a no no. Maybe there is something I'm missing though.

    Alistair.

  22. #22
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    There is no problem running multiple regulators off one tank. Commercial systems often plumb multiple tanks into a common manifold and multiple regulators off that. No problem.

    Its the same as if you have multiple regulators drops in your garage off your air compressor. Can run multiple tools simultaneously no problem. Now, if you tried to Tee the hose after a single regulator into multiple tools everything would come to a crawl on your impact wrench when someone else stepped on the foot pedal to use the sand blaster

  23. #23
    DWF
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    Quote Originally Posted by A. Spence View Post
    I have a thread going on the Google framebuildrs list right now where I asked about using a splitter or a "T" junction for running a purge line.

    The response I got recommended against it, because it could result in a vacuum being formed that interferes with the Argon flow to the torch, which obviously could be a bad thing.

    Is there a way of setting things up in the way you're suggesting that will avoid that?

    Alistair.
    You'd have to run a second flowmeter anyway since the torch and the backpurge would/should be running at different flow rates. If you ran a splitter downstream of the regulator you might have to compensate for the fact you're tapping off the machine's/torch's flow with another flow meter but I don't see how you could induce a vacuum into the shield gas line unless you had it running WFO and even then, you'd just reduce pressure as long as it was the back purge running off the T and not the shield gas solenoid. More likely you'd have a hard time getting sufficient flow to the back purge.

    It's really a moot point though. The way to do is it to either run a dual flow meter or tap into a sufficiently sized manifold log prior the machine's gas line with another regulator/flow meter. At that point, a dual flow is looking pretty $ smart unless you already have a spare reg/fm laying around.

    edit: I just saw smdubovsky's post and he nailed it.
    A man must have enemies and places he is not welcome. In the end we are not only defined by our friends but those against us.

  24. #24
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    Quote Originally Posted by DWF View Post
    It's really a moot point though. ... At that point, a dual flow is looking pretty $ smart unless you already have a spare reg/fm laying around.
    The CGA580 Tee is $23 from sears:
    Western enterprises CGA580 Male/Female/Female Tee - Tools - Air Compressors & Air Tools - Air Compressor Accessories

    Another ball flowmeter is $30+ (ebay/amazon/etc.) So a $53 solution vs $170? I don't see how a dual flow is smart $

  25. #25
    DWF
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    Quote Originally Posted by smdubovsky View Post
    The CGA580 Tee is $23 from sears:
    Western enterprises CGA580 Male/Female/Female Tee - Tools - Air Compressors & Air Tools - Air Compressor Accessories

    Another ball flowmeter is $30+ (ebay/amazon/etc.) So a $53 solution vs $170? I don't see how a dual flow is smart $
    You make a solid point. The T from Western is the exact one I use. Am I the only one amazed Sears has them?
    A man must have enemies and places he is not welcome. In the end we are not only defined by our friends but those against us.

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