welding vent and effects on sheilding gas

I am looking to build a vent to exhaust welding fumes ouitside. I have
a 600 cf Fan and will vent it directly outside. My question is with
the sheliding gas? I would think that the same draft for removing the
fumes would also effect/remove the shielding gas. Application is for
tig mig and plasma.
Thanks in advance for all resposes.
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You have to create quite a wind to disturb the gas. As a guidline the air should not be moving much faster than one meter per second. A big fan blowing can do that but a vacuum hose would have to be within an inch of your weld arc to influence it. In the shipyard we had two inch vacuum hoses with a funnel mouth about six inches in diameter. You could put that within a foot of the arc and not have any effect. If that same hose was blowing air out it would have been a problem. Randy
Reply to
Randy Zimmerman
Drafts can indeed affect your weld if they disturb the shielding gas over the molten metal. This is why processes which use shielding gas aren't generally considered appropriate for use outdoors when the wind exceeds about 5 MPH unless some short of shielding is erected around the work.
In my experience, there doesn't seem to be much of a problem if the air flow is minimal and pretty much straight up. OTOH, when the draft is from the side, sometimes I have to put up shields to cut the draft around the work. Sometimes it may seem like there is not enough of a draft to cause problems until you get to a particular point on the work, usually near the top.
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I do a good amount of my welding outside. I carry one of those great big rolls of aluminum foil that the sell at Sams Club that is something like 100 yards X 24 inches. Gas flow is set high and I make a wind screen out of the foil. I can shape it to how I need it, reuse it or throw it away as required. It beats always setting cardboard and paper screens on fire
Reply to
Diamond Jim
Sounds like a ring. I was in a rush to get my Plasma CNC machine up and running. I put a slice of plywood on the floor (to protect it) and nothing to the sides. I noticed some spray coming out and naturally 'balls of fire' - so I simply put up a folded box - cardboard. Not a tiny burn mark on the cardboard - only when the chunks and drops of metal sat on the wood did it burn the wood.
So lightweight material on the sides to protect is logical as the time spent touching is very short.
I plan to simply put a shallow box on the floor and determine what is useful for the two sides that need help. I want to create a tunnel for airflow out the building.
Reply to
lionslair at consolidated dot

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