Tungsten stickout & pressure/ flow

By Lawrence (*****)

Date 09-18-2008 16:43 Edited 09-18-2008 16:57

Lots of charts online.

All the tungsten manufacturers have em.

For practice, a simple rule of tumb is... Stickout no longer than the ID of your cup.

10-15 CFH for very small cups... 15-20 for cups 3/8 to 1/2".... Slightly higher if your cup is a gas lens.

This is good and free
http://millerwelds.com/education/TIGhandbook/
and
http://www.diamondground.com/HowtoPrepareElectrodes.pdf

and
http://www.diamondground.com/downloads.html

and
http://millerwelds.com/pdf/gtawbook.pdf

By seagull369 (*)

Date 09-21-2008 05:46

Thanks, Lawrence. Looked over some articles and what you said seems right on.

I didnt notice, however, any mention of what the regulator pressure should be in any of them.

If any of you wouldnt mind checking it out, the regulator/ flowmeter setup I have looks similar to this one:

http://store.rilandusa.com/images/argonregulator.jpg

Sorry about these Mickey Mouse questions, but is the dial gauge there showing the pressure in the tank or what the regulator is set to? Also, is the regulator adjustable? I noticed a threaded cap on mine with an Allen-type set screw inside, which makes me think it might be.

By aevald

Date 09-21-2008 06:38

Hello seagull369, the particular regulator/flowmeter that you have posted uses a regulator to take the pressure contained in the cylinder down to a much lower working pressure, I can't recall the exact pressures but I believe they may be as low as 15psi and possibly range to a high of around 35 psi. The "flowmeter" portion of this combo is the part that actually regulates the flow seen at the torch. The flowmeter is the portion that has the glass/plastic tube which contains the "ball", by adjusting the valve on the side at the base of this part you are allowing more/less gas to pass from the regulator portion of the assembly through the flowmeter portion where you can view the appropriate scale to determine the level of gas flow that will then enter the hose leading out to the torch assembly. You may also notice that there are possibly different scales identified on the tube inside, one might refer to argon, another helium, yet another might say Ar75/Co2,25, you will also notice that they are different in their position and their scale measurement increments. The ball inside this portion of the assembly is a certain diameter and the scale tube is a different diameter, depending upon the viscosity or thickness of the gas being regulated the ball will rise a different heighth. Argon is a heavier gas than Helium and will require a different scale and also probably be found closer to the base than the helium scale which will probably be located higher on the tube and the scale spacings will be further apart. Hope this explanation has helped somewhat with your understanding. One other thing that can sometimes help with understanding all of this is to know that there is a difference between pressure and flow. You don't need to adjust the part of your regulator/flowmeter that has the allen/nut, that is the part that determines the working pressure of the unit. The only adjustment you need to concern yourself with is the adjusting valve that is at the base of the tube/ball assembly. I could probably go through a bunch more information to explain this but I'm pretty sure you've got the idea. Best regards, aevald

By seagull369 (*)

Date 09-21-2008 07:03

Though I have a pretty good handle on pressure and flow differences, aevald, thanks for going through the trouble of explaining. Having seen the flowmeter in action, I figured that was what the ball was doing bobbing around in there, but it's good to know about the different scales for different gasses. I hadn't taken that close a look at it yet to notice that, but I'm sure once I did I would've been on here again asking about that too, so thanks for saving me the trouble!

By aevald

Date 09-21-2008 08:56

Hello seagull369, I generally qualify my explanations by saying: "if you are already aware of this information forgive me for including it", guess I forgot it this time. A few other general information type pieces that apply would have to do with the cup sizes. As the cup sizes decrease so do the flow requirements of them, that is where I really meant to include the pressure/flow stuff, because if you don't allow for the necking down and thus increased gas velocity you may end up with excessive turbulence in the shielding gas or possibly a venturi effect that will draw surrounding atmosphere into the weld area. There is also generally a difference with the flow rates for various cup sizes when they are being used in conjunction with gas lenses, or not. Gas lenses will allow for slightly higher flow rates than non-gas lens applications. I believe there are also some past threads that go into fairly decent detail discussing things such as stick-out, tungsten selection, tungsten tip preparation(angles,points,flats,rounding,etc.), torch angles and direction of travel and a whole host of other pretty decent suggestions for successful GTAW welding. If you haven't already, try using the search function to locate some of these. Enjoy your machine and keep us posted on how it's going. Best regards, aevald

By 522029

Date 09-21-2008 13:40

FLOWMETERS for argon have the pressure pre-set at (usually) 15 psi. The pressure is not readibly adjustable. The float ball or the flow gauge indicate CFH of flow. The tank gauge will show PSI left in the bottle.

Griff

By seagull369 (*)

Date 09-21-2008 17:26

No worries about the lack of "forgive me for including it" blurb. I usually end up learning something new even about topics I thought I knew everything about, so it all works out.

I actually did (believe it or not) do a search before posting but didnt find much that 'readily' appeared to answer the questions I had.

Good to know about what that gauge shows, Griff. I'm more used to setups like on air compressors, where the pre-regulator gauge shows pressure in the tank and the post- one shows pressure afterwards, so it threw me for a loop.

Ill def let you know how things works out, and thanks for showing an interest. =)