Welding Tips and Tricks

Is there really an issue leaving the gas up on the TIG unit? All the stuff I weld is really tiny - Seems like I waste more gas than I use purging out the gas. Nobody goes into my shop so there's no chance for somebody to fool with anything.
Z

Z,

If I understand you correctly, you think leaving the gas on saves gas over what it takes to purge your lines?

That depends entirely on how tight your system is, but you don't have to purge lines just because the gas was off. If there's still pressure showing on the gauge, you're not "leaking air in" to your lines.

The safer bet is to close the argon when done. Even if you lose all line pressure, it takes less than a half-second to purge your lines unless you have some unusual setup.

Welcome to the group!

Steve S

Steve, Thanks for getting back to me. I watch the gauge drop from 1500 and it seems like a lot of waste. System is killer tight.
Someplace I thought there was supposed to be some kind of potential for a problem if you left the Tank pressure against the System.

Good to have place to ask this kind of thing - the experience is a treasure trove!

Z

turn off your bottle but just don't bother to bleed the lines. that way you will never lose more gas than what is in the lines. and if it really tight, you won't have to purge next time.

I also always close the bottle and leave pressure in hoses. Next day I will check the pressure and if it have dropped I then know that system leaks.

Steve I have to disagree with purging time. Of course it depends that how long your gas hose is, but in orbital welding I have noticed that cleaning all the moisture can take one full weld before system is 100% clean. Even if lines are prepurged.

Little off topic, but it's also good to keep in mind that inpurities goes trough your hose. Gas atoms are relativily small and will penetrate hose. Even if gas hose inside pressure is greater than atmospheres.

Welcome to forum

Zondfive wrote:Steve, Thanks for getting back to me. I watch the gauge drop from 1500 and it seems like a lot of waste. System is killer tight.
Someplace I thought there was supposed to be some kind of potential for a problem if you left the Tank pressure against the System.

Good to have place to ask this kind of thing - the experience is a treasure trove!

Z

Actually, the only thing that sees tank pressure is the regulator. All the hoses downstream see the regulated pressure, usually 50 or 75 psi on a "ball" type flowmeter, and quite a bit less on a two-stage regulator style.

Markus has a point about moisture and air infiltrataing unpressurized lines, and I'm used to having only 25' of 1/8" line on teh thorch side of the gas solenoid, so usually a second of pre-flow is plenty. However, when I get out my dry-rig, I have to assemble it and purge 125' of 1/4" hose, so I purge it a couple minutes, but this is at work and I'm not buying the gas.

There are also several ways to reduce "gas surge" at start-up, for further gas savings, and there's a topic somewhere in the TIG forum about it. I'll see if I can dig it up.

[EDIT] Topic on gas surge here: http://forum.weldingtipsandtricks.com/v ... f=5&t=4561

Steve S