Fume Extractoion & TIG Welding

[Jigantor]

Wanting a fume extractor has prompted us to test if shielding gas is influenced.
We tried getting images of smoke but gave that away as it is like photographing a ghost.
So we came up with this simple candle apparatus.
We are only using a small & cheap 10 year old shop vac for the test with very small amount of suck. I am not sure how strong the flow of gas coming out of the torch is that can be tested and filmed easily. That said we found in our smoke tests that the vac nozzle had to be within 200mm to catch say 90% of smoke.

The first image is candle with vac off.

Ji

[Jigantor]

The second image is with shop vac on.

Ji

[Jigantor]

Third image has the nozzle 450mm away from the flame.
This would not suck up much smoke from our tests.

Ji

[Jigantor]

The forth image has the nozzle at a 45 degree angle.
This in our smoke test was pretty poor at smoke removal.
But even at this distance and angle the flame is still bent towards the nozzle.
It seems that you get good fume extraction but deflection of shielding gas.
I am not sure if this would be a problem with welding but after we do more tests we may know.

Anyone had any issues with fume extraction and shielding gas?

Ji

[Jigantor]

Using a Kestrel wind meter I determined the air speed at the 100mm or 4" diameter nozzle. It was 8m/s.
Using my calculator I found out that the flow was 63 l/s or 3780 l/m or 133 CFM.
Miller's Filtair 130 has 62 l/s or 3720 l/m or 132 CFM.
They suggest that the nozzle should be less than 150mm or 6 in. with accys or Bernard™ FILTAIR Gun to the arc.
Wow that is close with that kind of flow.
Has anyone got one of these units that can tell me how that kind of flow effects the shielding gas when Tig welding?

Ji

[Ltbadd]

Has anyone got one of these units that can tell me how that kind of flow effects the shielding gas when Tig welding?

Ji

How about making a test weld, and see what happens?

[Jigantor]

I could make some test welds but need a measuring device.
The other day while testing wind speed with my Kestrel the propellers ripped off.
They are only rated at 60m/s and my shop vac produced 80m/s.
When the $50 replacement propeller turns up I can start testing again.
You see I need to find out what the flow is at 1", 2", 3" and so forth away from the nozzle. That way I will know at what distance the system will work every time, including those times when the filter blocks up reducing flow.

Ji

[Jigantor]

I tried smoke but that was too much to live with and then steam but that is impossible to get an image of.
I did notice with the smoke that the extractor did not get all of it. Some smoke went to the sides of the nozzle. I could see a low pressure vortex swirling around the side of the nozzle. These low pressure vortex issues may be resolved by a different shape nozzle. After a while the swirling smoke would be sucked up. A fog machine would give consistent results that could be photographed but they cost too much for me.
The candle flame test was the best and easiest to take pics of.
Interesting, that the wind speed varies depending on the inlet tube or nozzle size but the flow rate stays the same.

Ji

[Jigantor]

The Kestrel propeller turned up today so back on the fume extractor.

I wanted to see if nozzle shape played any part in extraction.
With a smaller nozzle diameter that is rubber I took an air speed reading. The rubber nozzle allows me to push it around into different shapes to see what happens.
I also took a reading at the outside edge to see if there was any air speed difference.
I found there was. Probably due to the stepped nature of this nozzle build, causing a shadow effect.
Then when I squeezed the round nozzle into an oval shape I found the air speed equalised.

Ji