[jakeru]

I am getting my TIG setup ready for doing back gas purging, to do stainless steel tubing like headers, containers, etc. (Without relying on solar flux.)

I wanted to share what I've done so far for this, and get some advice on how I should finish setting this up.

So far I bought an extra outlet valve / fitting for my HTP flowmeter, and fit it into the flowmeter using a 1/4" NPT air tee fitting I got from the hardware store. I now have two adjustable outlets on my flowmeter - one for the back purge hose, and one for the TIG torch.

The hose barb ends off the flowmeter nipple are 3/16", and I still need to buy some purging hose. Is some kind of special material recommended for this (such as heat resistant silicone rubber?) I'm wondering what is the likelihood that the end of the hose would touch a very hot part and should be heat resistant. Otherwise, perhaps just some 3/16" rubber oxygen type hose, or some other type of flexible hose I can find at the hardware store will work?

I was thinking to start off trying the back purging, I might just stick the hose into an open end of a part I am going to weld (such as a piece of stainless tubing), and bunch up some aluminum foil and stuff that in around the tubing to seal in the inert purge gas.

Any other tips for how to get setup and use inert gas back puring for TIG welding would be appreciated. Or maybe see some pictures of other people's back gas purging setups? Thanks

[Rugar]

How are you going to know how much working pressure is coming from each outlet? I suppose as long as you get a decent seal on the work piece, and can just purge and then shut the valve off it would work. If you require constant purging flow, I cant see this working because of no way of knowing the flow rate from the torch nozzle.
I suppose the hose material would depend on the size of the work piece, how far away the hose needs to be from the heat of the weld, and how long the heat would be applied to the material be welded.
Ive never tried any of this as Ive only had my TIG machine for less then a month. Kinda just thinking out loud here. Looking forward to see how this works out for you.

[kermdawg]

Rugar is right, your going to need some way of knowing how much flow you actually have going into the piece that your purging. A seperate flow meter I think would be best, but you can also get one of those oxygen analyzers and test near the outlet of what your purging to see if you have a truly inert atmosphere inside the piece.

I think if I was going to do it, I'd get a completely seperate setup, a whole seperate bottle of argon, flowmeter, the works. Thats just the way I'd do it. I would think your going to be changing out that single bottle of argon an awful lot, what with the back purge AND the shielding gas on your torch. I just think 2 bottle would be alot easier. Again, just my opinion.

edit: Ya know what might work for ya too, depending on how your shop is set up, is a manifold system. A basic one wouldnt be that difficult, or expensive to set up. Just need some copper pipe, brazing rod, and you can completely customize it depending on your work too. THAT would be how I'd do it, again depending on space/how much you wanted to big deal it. You could even get an alarm that would go off when the inlet pressure starts getting low, so you dont run out of gas when in the middle of a critical weld.

[Rugar]

This would be the easiest.



http://store.cyberweld.com/viredfm150du.html

[gurew]

unfortunately..for the cost of that regulator, you can buy a tank, full with argon, and a cheap regulator and bam dedicated tank for purge/backup for main tank....thats what i did and i now have a backup for each..total of 4 tanks

[jakeru]

Hey guys - thanks for giving me your attention on this.

I think my setup is going to work fine for setting and controlling flows individually out each outlet; in fact I have already tested it (just for setting flows so far- not for actually doing any welding yet) and the flow adjustments seem to work great and seem completely independent of each other. The way these flowmeters work internally, is there is a pressure regulator that tries to maintain a set constant pressure. (In the case of this particular flowmeter, that internal pressure is 50 psi.) Then all flow out the regulator goes through the floating ball gauge, and on to a needle valve (which is above the outlet, and under the knurled knob), which restricts the flow to a finely controllable amount.

All I've done is added a second needle valve and outlet, in parallel with the first one. As long as the regulator can still maintain a constant 50 psi internal pressure, each output flow should be adjustable independently.

Of course, since there is only one "floating ball" gauge, (which reads the combined amount of the flows,) sometimes math is necessary to determine the flow out of just one outlet. But I don't think its going to be any problem. Here is a very simple heuristic I can use to tell what each individual flows would be when I am using both outlets:
1. While not welding (and not in pre or post flow), the solenoid in the TIG machine is closed. Read the flowmeter. It will indicate the back purge flow.
2. Next, trigger the pre-flow and read the flowmeter again. When the solenoid is triggered, the total flow will increase. The difference between the second and first read is the TIG cup flow.

...Easy as pie.

As a side benefit of it all going through one floating ball gauge, I can now set a very small flow much more accurately than I could in the past. By creating a "controlled leak" to put the flowmeter into a readable range, I can then set a second flow so it causes a very small increase. (Let's say, 2 cfh.) Then I shut off the leak, and the remaining flow should be 2 cfh (which would by itself not be enough to get the floating ball of its seat.) Without the leak, the lowest the flowmeter reads is about 10 cfh. I've set < 10 cfh before by kind of "winging it." Being able to set a very small flow might be useful for backpurging - I don't know yet though. I think it will be useful for setting a precise, useful flow out of a very small TIG cup, such as a #4 cup.

[Rugar]

I guess that would depend on what size tank you get. The larger you get, the cheaper it is per CF when you refill it. It would also depend on how often your needs are for purging. I use 300CF bottles for both MIG and TIG.. Sucks when its time to load the heavy beasts in the truck for a refill, but on the other hand I dont have to get refills as often.

[jakeru]

By the way, here is a picture of what the flowmeter looked like before I modified it with a second outlet.

The parts for the conversion so far are only about $23.

[tigmaster]

use foil folded in half and a hoseclamp tightend around the end of the tube....remeber topoke a hole about 1/8 in diamter for a vent hole....and tape up the other end with the hose in it

[Poland308]

I have used this method of both off of the same flow meter. It isn't optimal but it does work. I can do a lot of welding off of a 125 cf tank like this. I use my scratch start rig and shut down the torch flow. Then set the first needle valve for the purg flow befor I open up the flow to the gun. If i know I need to do more than a few welds like this I just rent another tank for the project.

[LtBadd]

We have a lower cost option for a dual flowmeter:

http://www.usaweld.com/Dual-Flowmeter-w ... 1&CartID=0

We also sell bulk hose. It is the same hose we build our gas hoses out of. Our P/n is 20340. It is a reinforced vinyl hose. 3/16" ID with a 5/16" od.

Thanks for the post w/link, this is a great option and price!

Richard

[Braehill]

Mr. HTP,
I'm not sure if you took the time to read the forum rules when you joined, but if you haven't, please do. You can place your website in the signature line, but advertising isn't permitted. This isn't a place for promoting your sales.

If you feel you can add to the conversation without promoting your products feel free, we're all ears. I'm sure you can find something to add with your knowledge of the equipment available without making a sales pitch.

Len


Sent from my iPad using Tapatalk

[weldin mike 27]

This is the guy who got warned off a while back.

Sent from my ZTE T83 using Tapatalk

[LtBadd]

Mr. HTP,
I'm not sure if you took the time to read the forum rules when you joined, but if you haven't, please do. You can place your website in the signature line, but advertising isn't permitted. This isn't a place for promoting your sales.

If you feel you can add to the conversation without promoting your products feel free, we're all ears. I'm sure you can find something to add with your knowledge of the equipment available without making a sales pitch.

Len


Sent from my iPad using Tapatalk

Oops, I didn't know

[Braehill]

Richard,
That's not on you, all him.

Len

[nathan]

Got this setup right now, and that original part is hard as HELL to get apart. What's the trick to doing this without breaking everything??