tig welding gas problem

[Mel]

I don't have room for the large gas bottle anywhere near my welder. So what i have is about 15-20 ft of 10mm bore hose fitted onto the regulator and a flow valve near the welder i can shut off and disconnect the welder. I figured doing this won't waste any gas when not in use.
The problem is, when the flow valve is turn off or you stop welding for a a few seconds the pressure of gas (even though it is regulated) builds up in the hose, and you get an instant surge of gas before it flows steady:confused:.
I reckon' the answer is to keep the gas in the hose regulated to around 30 psi (which one of my regulators will do easy) and the use a small regulator fitted near the welder to further reduce the pressure. This way the pressure and flow will have less chance of pressure build up. I have tried it out with the small regulator on the bottle with short and long lengths of hose and it does seem to make a difference.
Now, before i destroy a perfectly good regulator by getting the inlet fitting machined down so a hose will slip over the end, anyone out there think of a better solution? or of you have had the same problem or should i just carry on and put up with the gas surge?
(Did any of the above make sense? if not i'll try to explain further)

[Dannys Chevy Parts]

i'm using a tig welder but the bottle is strapped to a cart with the welder i don't experience any problems. you may like to check the following site out as i have found the guys on there to be very helpful here is the web address www.mig-welding.co.uk hope it helps
Danny

[rem]

30psi sounds a lot? You could pump your tyres up with that!

I have a dual gauge regulator on mine: one gauge reads bottle pressure up to 300 bar, and shows basically how much gas is left, and the other is a pressure gauge which I'm sure I run at around 10psi max (can't check 'cause I've just run empty). I'm not sure that gauge is working correctly anyway, so I intend to replace it with a (volume) flow gauge. Remember, you are only really keeping oxygen away from the weld pool and arc, not plasma cutting :)

[rem]

HP Books' Welder's Handbook says to use 10 - 25 cubic feet per hour - "..any less would not purge the weld...more than 20cfh would be wasteful and could cool the weld too fast..."

[Happydaze]

Mel. My setup is kinda similar in that i have a longish gas hose but it's 'only' 6mm id or so. I get what certainly sounds like an initial surge but until now haven't thought anything of it :rolleyes:.

What's the problem? It doesn't affect the weld as you've not started even by the time its gone (it is very momentary).

Wasted gas? Buy more ;):p.

But maybe your surge is bigger than my surge? You've got a much larger resevoir by virtue of the diameter of the tube. My small diameter (thick walled) tube delivers plenty o gas even when welding on higher power - mines admittedly only 150a but i've never found it necessary to be much over 110a, even for chassis work. Cleanliness, good prep, root, fill and cap on thicker stuff (eg 6mm) no problemo :cool:.

Chris

[Mel]

Rem
Yes, that around 10 litres per minute. 30 psi was just a figure i thought of because the second regulator would need a certain amount of pressure to work ( i guess). All i really want is a nice steady flow of gas (3-4psi) without the surge.
I've thought off using a flow meter , but it doesn't actually do much other than being an indicator. other than strapping the sodding great bottle on the back of the welder which means making up a trolley which i don't have room for, hence the problem.
Danny, useful link thanks.

Chris, that justs it, i really don't know if it's a problem or not, but i'm trying to fix up a setup that would seem better to work with.

[dustyrustee]

FYI: flow meters are different than gas regulators. they fix the pressure at a constant and allow only for very precise flow adjustment at constant pressure, without rise. They are more than just a regulator with an indicator. They are different internally.

you will not get the result you are looking for with an ordinary regulator....they are not designed for the purpose and will not yield the required result.

you need the right tool for the job.

[rem]

Yes, I believe the Argon flowmeters use a calibrated orifice to regulate the pressure at the specific flow rate setting?

If you have the correct set-up on the bottle, is the gas not switched on and off with the torch - as Chris said, is it really noticable during the start of the arc? Mine is scratch-start so I am sure the gas surge (if any) has gone by the time the weld starts.

[105e van]

dont think you`ve got any problems mel.i`ve always experienced an initial surge even when using a mig welder.the only time when i hav`nt had any gas surge is when the valve is on the torch itself(scratch start without footpeddle operation).the surge is probably due to the build up of gas in the pipe that passes thro the welder.the flow gauge will regulate a constant flow of gas but it wont stop the gaqs pressure building up after it when you stop welding.the welder itself will have a stop/start valve inside it(unless your using the torch with valve on it),the surge is most likely the build up of gas between the flow gauge and the valve inside the welder. hope this helps....stu

[langysrodshop]

Mel i use a Flowmeter on my TIG & MIG, They will save you a fortune in Gas.