Purging

[Aaron_]

In the near future I want to have a go at making a exhaust manifold I was wondering can I purge and weld from one bottle

 

[Aaron_]

Haha now how do I plumb it in

 

[Jim Davey]

Valved Y-connector two flow meters, two pipes and one regulator.

 

[Paul.]

You need a splitter, it just fits to the regulator outlet, then connect one to the purge line and the other to the welder.
http://www.weldequip.com/twin-outlet-valve.htm?cat2=24

 

[Tigman]

and watch your gas disappear rapidly

 

[Aaron_]

Cheers guys that's just what I was looking for but Google wasn't being my friend

 

[paceman1]

wont your purge need to be lower pressure than at your weld torch

 

[Paul.]

Here is my set up, you can make do without the flowmeters if you really have to,

 

[dobbslc]

I suppose it's just got to be enough to keep air out, so a small positive flow should do it.

 

[paceman1]

nice simple set up there paul

 

[Aaron_]

I'll order 2 flow meter too then

 

[addjunkie]

Restrict the outlet hole if you can saves gas.....your only purging what your welding not the workshop and universe

 

[chevy2]

Here is my set up, you can make do without the flowmeters if you really have to,
View attachment 80576

That picture could have easily been taken in my workshop,
My setup is identical to yours.

 

[Richard.]

wont your purge need to be lower pressure than at your weld torch

Lower flow rate slightly.
Set them individually on the tube valves.

 

[Brad93]

Purge it at say 10CFH/6LPM for say 2 minutes to remove the oxygen then you can lower it to say 2-3lpm and commence welding. Remember Argon is heavier than air.

 

[addjunkie]

You also dont live very long if you try to breathe it........so be wary in garage pits and such.

 

[Brad93]

Please note thats just for example, best thing to do would be calculate a rough volume of the pipe you wish to purge then aim to turn the volume over a number of times before welding to ensure all the oxygen has been evacuated from the tube/pipe/cavity. Once youve done a few experience will tell you how long you need to purge for then what flow rate you can get away with whilst welding. Professionals welding titanium and the like use inflatable dams and purge monitors measuring atmosphere in ppm etc.

 

[Paul G]

A couple of tips from an old codger whose been backing welds since time immoral.

Better to flow gas gently through a large pipe than to squirt it in at high velocity through a small orifice.

A ball of stainless wire wool over the gas entry point will gently defuse the flow, and providing gas enters at the low point
the object will gently fill, rather than having to "turn over the volume several times."

It's a bit like pouring cream over black coffee. Mmmm.


Paul G

 

[AndersK]

I like to use pneumatic mufflers as diffusor. Those and the push connectors are really cheap.

Some images to give some ideas.
The aluminum block are for purging inside corners.

 

[Richard.]

I like to use pneumatic mufflers as diffusor. Those and the push connectors are really cheap.

Some images to give some ideas.
The aluminum block are for purging inside corners.
View attachment 80805

View attachment 80806 View attachment 80807 View attachment 80808

The jobs your doing there Anders look top notch.
My purging set up is more similar to Paul's description. A fairly large diameter pipe with a push fit connection I have a few different brass ends to attach to it depending on where it's going from a very thin flattened pipe for getting behind backing bars etc to a funnel type for inside tubes. Wire wool is a great defuser as is scotch brite.