Gas Lens

I have a question regarding the use of a gas lens. I've read whatever I could find on the subject but so far have come across nothing other
then "sometimes they are better" sort of comments but my dealer tells me that they are a gas saver, i.e., you can turn the gas flow down when using them.
Does anyone have any definitive information about gas lens and their use, or reference to this information?
The welding in question is mostly 1 mm SS tubing, say 1" to 1.5" diameters.
Cheers,
John B. (johnbslocombatgmaildotcom)
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Always use one unless it is too bulky to fit in where you want. I would say that is the short answer. I am not so sure about the gas consumption but you can stick the tungsten out farther with the gas lens. Of course if you have a stock of non gas lens ones and have to buy the gas lens stuff you could factor that in. The cups that are kind of pinkish are superior to the ones which are kind of whiteish. There are quite selection of opening sizes on the ceramic cups.
Fran
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On Wed, 2 Jun 2010 11:06:42 -0400, "fran...123"

Not to be insulting, but that is exactly the sort of things I have been reading.
My questions were intended more to get information such as recommended gas flow per materials welded and when they are specifically recommended and when not, as most articles say "recommended in some cases...".
When I got the new torch, a WP-9, I also bought several sizes of lens and cups to try out.
Cheers,
Schweik (goodsoldierschweikatgmaildorcom)
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That would be a trial and error thing, as TIG torches are used for things so specific that each weldor almost has to make their own little record book for exacting uses. Like outside corner fusion welding of 16 ga. stainless. Yes, there are some guidelines, but a lot of it has to be arrived at by the weldor, and will vary from weldor to weldor.
There is no book you seek that has an encyclopedia of thicknesses, gas flows, gas lenses, etc, but only parameters, guesses, and general ideas. If you notice on most of them, they have a - inbetween numbers like 8-12, meaning 8 cfm to 12 cfm, but a lot don't have one specific number. Yes, there are encyclopedic books on these subjects, but if you have any real experience, you know they are only a starting point, and from there you fine tune.
HTH
Steve
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snipped-for-privacy@invalid.com says...

I've always used one because it not only allows more tungsten stick-out but also improves shielding gas flow. You'll get fewer rejects and burn up fewer tungstens.
When I say "improves flow," I mean there will be less turbulence (mixing of argon and air) created by the argon as it leaves the torch, providing better shielding.
If you get rejects while using a gas lens, first check the lens to ensure it is clean. Then check your flow rate to ensure it's not cranked up too high. IIRC, you would want around 25 cfm
Never use a wrench to tighten the gas lens and cup, just use your fingers. As the torch heats up, if those are wrenched on there they won't last nearly as long.
--
Tin Lizzie
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wrote:

The articles I've read were worded like "recommended in some cases...", "sometimes improve..." and so on. I was trying to figure when they are better and what sort of gas flow to use and things like that as frigging around with a bunch of 1 inch tubes seems to use a LOT of gas. I'll try the 25 CFM - err... that is 25 CFH, isn't it? I am using between 15 and 20 the moment.
Cheers,
Schweik (goodsoldierschweikatgmaildorcom)
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Schweik wrote:

Unless you are running a really long stickout on your tungsten or working outside, 15 CFH is probably enough.
BobH
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Yes, it's about 25 CFH. Sorry! I musta been off in la-la land. The flow rate I use varies depending on the configuration of the weldment. If I'm doing overhead, I'll use more gas. Welding flat, I'll use less. If I'm going around a stationary horizontal pipe I'll set my flow between the two and keep a close eye on the base metal to ensure it doesn't start popping and spluttering.
Too high a flow and you'll get rejects caused by the mixing of the argon and air (turbulance). Too low, and you'll get rejects from insufficient shielding gas (tungsten turning colors, smoking, base metal oxidation, porosity).
The range I'm used to is between 15 and 30 CFH.
I would recommend purging the pipe, too. If you are, use 100% argon to purge the pipe, set at a low flow (5 to 10 CFH), bearing in mind that argon is heavier than air. Imagine flushing the pipe with water- which way will it flow? Allow the argon time to gently push the air out of the pipe. Construct a dam on the uphill end of the pipe using a pipe cap with a small hole in it or a piece of tape with a small hole in it.
That'll keep the inside of the pipe from oxidizing ("sugaring") and will give you a much better / longer-lasting weldment.
--
Tin Lizzie
"Elephant: A mouse built to government specifications."-Lazarus Long
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wrote:

Yes I usually step on the pedal for a moment after I turn the machine on and it is also set to allow a preliminary pause before the current switches on so I don't think that there is a problem there and I've always used sponge disks in either end of the tube with a purge argon flow. The setups I learned on just had a valve in the line. When you weren't welding you hung the torch on the valve extension and that turned the gas off.
I learned the sponge trick from a Boeing project. They had a contract to remove every piece of stainless steel air conditioning and heating duct in the airplanes, clean and bead blast and repair cracks. Rather then a multitude of solid plugs they had a few circles of about 2 inch thick foam sheet cut and just stuck one in each end and then poked a purge line in one end. Perhaps it is a common trick but I had never seen it before.
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Schweik (goodsoldierschweikatgmaildotcom)
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The only reason to use a standard collet body is if you are still new to TIG and need to hide your tungsten inside the protective shield of your gas cup.
Standard rule is you can extend your tungsten 3 times the diameter of the tungsten beyond the cup. This places a 3/32" tungsten at 9/32" extension.
With a gas lens you can go 6 times the tungsten diameter which would be 9/16" for a 3/32" tungsten.
I use nothing but gas lenses, and I use the largest cups I can fit. On a #2 series torch that means a #8 cup (1/2" ID) On a #3 series torch you can go up to a #12 (3/4" ID)
This gives me the greatest coverage. A gas lens does allow a lower gas flow because the gas is coming out in a smooth lamilar column, rather than an erratic spurt of gas, like you get with a standard collet body.
Standard gas rates are about 20 - 30 CFH. With a gas lens you can go down to 10 - 15 CFH.
I especially like the super wide gas lens made by CK Worldwide. It uses a glass gas cup with a 1.25" ID.
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My short answer is that a gas lens narrows the flow of the gas so that your total length of the part of your torch that sticks out from the body is increased. This makes things a little better visibly, although it does narrow down the area that gets gas, so you have to be careful not to travel outside the gas path and get contamination. It might even cause one to use slightly less gas as the opening is narrowed. Am I right?
Steve
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What's that Lassie? You say that Steve B fell down the old sci.engr.joining.welding mine and will die if we don't mount a rescue by Sun, 20 Jun 2010 22:17:53 -0700:

The lens prevents turbulence in the gas, so it doesn't disburse as quickly. This allows for a longer stickout of the tungsten.
Usually the gas lens cup is larger than a plain cup rated for similar flow rate. This makes a wider zone protected by the shielding gas.
--

Dan H.
northshore MA.
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