A gallery of home built hoods and fume scrubbers _hood_

[Emryst]

little video of home-made hood vent. made from simple 2x4 lumber, OSB, flex seal, lites, fan speed control, etc. love it! just need to finish with front roll-up plexi-glass cover and shelving doors.

Dang I'm just getting startered with this whole thing. Building my first hood myself. But are you in florida by any chance. I'll have to hire you to wire up my next hood. Unless I can lock down that large refiner to buy my castings for 98% of spot and buy one of those fancy deals like sreetips got.

 

[Emryst]

This is a larger hood in a commercial refinery but it still demonstrates one basic method to allow the NOx to be collected and sent through the scrubber. These beakers have had the watch glasses removed because they were ready for the next step. The watch glass directs the fume from the pour spout into the pickup tube.
View attachment 63659

Amazing idea I will work on incorporating that into my hood. I'm working on the scrubber atm. I am a wood working hobbyist so the hood build isn't that much trouble.

 

[Yggdrasil]

You have to have a fan powerful enough to compress the airflow through the taper because the air that expands back to its original volume is what draws the air from the hood. So keeping the resistance as small as possible for that flow of air out of the hood into the duct is critical and a strong fan is needed to compress that air. I do not think a bathroom fan will suffice.

I think this is how he thinks about bathroom fans, without the main fan no venturi.
They will fail relatively fast but will be inexpensive.
https://goldrefiningforum.com/threa...s-and-fume-scrubbers-_hood_.34601/post-378283

 

[Martijn]

What 4 metals said. Powerful enough, that depends per case. The bigger the restiriction, the more power you'll need to keep an acceptable air flow from the hood going, but also the more air you'll suck out. It's a balance which you will need to try out to stay economical, or over dimension it to be on the safe side.
And keep the pipes after the venturi free of too many bends and restrictions. The vacuum created by the venturi depends on easy flow from venturi all the way to the exhaust.
another thing to mind is keep your exhaust far from your fresh air inlet, to avoid sucking the fumes back in your lab.
but you'll have to try it yourself.
Even the position where the restriction outlet is in the Y-piece is critical to get the best vacuum generated. A little flow restriction through the fumehood (e.g. a closed fume hood window, vent openings almost closed) actually makes a venturi operate better, but give lower airflow.
Aren't physics great?
So you'll want to have the right ratio pipe diameter vs restriction opening vs fan power /output.

Good luck making something that sucks... air well enough