This is the same
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A gallery of home built hoods and fume scrubbers _hood_
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The fan is the circle at the start of the straight pipe.
Like this:
That's it? NO exhaust fan to assist the extraction? I'll really have to figure out the placement of the fan though. Kind of tough with what I have in hand. It also means I'll need to have a really strong blower then right? What are the minimum specifications of the fan I should be looking at?
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I used one from these inflatable bouncing castles.
Of course the airflow can't be to restricted as the efficiency drops fast.
Any inline fan downstream will eventually die.
Edit for precision in language
Of course the airflow can't be to restricted as the efficiency drops fast.
Any inline fan downstream will eventually die.
Edit for precision in language
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Just checked, these jumping castle blowers are quite pricey and I'm way too tight on my budget for that. Don't you think a restroom exhaust be enough for the space I have? But that would eliminate the entire venturi setup.
Well, they will work for a few months, maybe....
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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.
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.
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.
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
Well-known member
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
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
These are not powerful enough to make nice airflow (and also generate poor pressure drop - meaning adding few kinks on the ducting and prolonging it and you practically make it useless) and thus unsafe to use with common size fumehoods. Of course, some fan is better than no fan, that is for sure. But I will not "cheapskate" this, since reliable hood is one of the most necessary things refiner should have.
You do not necessarily need to use venturi setup for fumehood, but be prepared that conventional radial or axial fans with unprotected metal parts inside will eventually die. Much much quicker than if they will suck normal air. I will upgrade the setup then and use fume extractor tube as 4metals shown - and this will be with venturi for sure. For this, less powerful blower would suffice - thus making it cheaper on this side.
Another benefit of using the venturi setup is by mounting the air intake for the blower outside your lab you will exhaust less air from your workspace but the air exhausted from the inside of the hood (where it matters) will give good fume exhaust. This really matters if you live in an area with cold winters where you need to heat the refinery.
@Yggdrasil is probably the member here who can appreciate this the most, while living in the Philippines heating of the airspace in the refining room is probably never done, but while he resides in Norway, it matters. Then again, if he made tons of money refining, he may air condition his refinery in the Philippines and then it does matter.
@Yggdrasil is probably the member here who can appreciate this the most, while living in the Philippines heating of the airspace in the refining room is probably never done, but while he resides in Norway, it matters. Then again, if he made tons of money refining, he may air condition his refinery in the Philippines and then it does matter.
Yeah, I can relate to this. We have rated hoods in our workplace, and it is hard to cool them down in the summer - as the AC unit try the best to cool the air in, which is in turn exhausted out...
Wasteful practice. We do have phase converters (or inverters? - basically the circuit that change the frequency of mains voltage - which in turn regulate the speed of the motor) paired with our fan motors, so we can adjust the power of the fans - not the best practice, but when I don´t work with toxic substances, I do not need the hood to be cranked to the max. One "lifehack" of our older colleagues was to use some harmless, but very smelly chemical as "flow indicator" - chemical you are able to smell below 1ppm levels or so. They usually opened some old bottle of mercaptane/thiophenol/dimethyl disulfide in the running hood, while executing the dangerous chemistry. If by any chance you will be able to smell it, crank the power to max and evacuate yourself
Sounds lowtech and pretty basic, but it works very well.
One basic thing I always try to instill in people I am trying to teach to refine is always have a clear path to run. When you need to evacuate quickly you don't want to be side stepping drums and buckets.If by any chance you will be able to smell it, crank the power to max and evacuate yourself
Well thanks to each and everyone of you for your useful and helpful responses since my last post. I'd actually been busy trying and experimenting this past week on the setup that I'd to make especially in orientation with the airflow being sucked by the venturi as well as a pc exhaust fan.
Something that I think may have missed out by the members is the video I'd shared earlier that my setup is basically in the alley outside my house, so its not an enclosed lab but also not very open to perform these tasks safely. I live in the lower portion, there are owners living above, and there are neighbours just about everywhere so the exhausting still needed to be taken care of. I personally wanted a scrubber setup with this cabinet but I really can't figure out how I can achieve it despite giving it many attempts. It was time consuming and already too much had passed so I decided to move on.
Henceforth, I built this
As marked :
1, BLUE : Pipe opening for the insertion of a blower
2, RED : Y-T as opening for the venturi air suction, tested over a beaker with hot water. Sucks good enough, but not much suction without the watch glass so some of it will escape and be caught by the exhaust
3, GREEN : 12v 4.5 amps blower with a PVC cup cut out on the bottom, to increase the length I tested it out with the tube of a tissue roll but that doesn't seem like a viable option when in full mode operation. Can someone give me a better idea for that please?
4, YELLOW : 12v 1.9 amps PC fan exhaust. (needs distance testing)
This setup will be enclosed with a glass or plexiglass from the front as doors. Although it just seems fine and not perfect per se, I'd like to see a feedback from you seniors.
Something I don't understand or make it out is as you can see the exhaust piping starts with a 6 inch coupling=>pipe=>6-4inch reducer=>4inch pipe=>then the Y-T. How come the air is still blown of the angled section of this T? (I hope I'm getting this right because I forgot to mark it.) When I tested earlier with a different DIY contraption, the air blew right out a 3inch pipe without any issues. In fact earlier, it was a 90 degree elbow only in the middle of the contraption, that too sucked the air but this one having given it so much space, it still blows out. What could be wrong here? This is also a concern as the piping of the blower and the exhaust connect here. A 45 degree will connect with the blower to the main exhaust piping and then the piping blow continues.
Many thanks for your time again
Something that I think may have missed out by the members is the video I'd shared earlier that my setup is basically in the alley outside my house, so its not an enclosed lab but also not very open to perform these tasks safely. I live in the lower portion, there are owners living above, and there are neighbours just about everywhere
so the exhausting still needed to be taken care of. I personally wanted a scrubber setup with this cabinet but I really can't figure out how I can achieve it despite giving it many attempts. It was time consuming and already too much had passed so I decided to move on.Henceforth, I built this
As marked :
1, BLUE : Pipe opening for the insertion of a blower
2, RED : Y-T as opening for the venturi air suction, tested over a beaker with hot water. Sucks good enough, but not much suction without the watch glass so some of it will escape and be caught by the exhaust
3, GREEN : 12v 4.5 amps blower with a PVC cup cut out on the bottom, to increase the length I tested it out with the tube of a tissue roll but that doesn't seem like a viable option when in full mode operation. Can someone give me a better idea for that please?
4, YELLOW : 12v 1.9 amps PC fan exhaust. (needs distance testing)
This setup will be enclosed with a glass or plexiglass from the front as doors. Although it just seems fine and not perfect per se, I'd like to see a feedback from you seniors.
Something I don't understand or make it out is as you can see the exhaust piping starts with a 6 inch coupling=>pipe=>6-4inch reducer=>4inch pipe=>then the Y-T. How come the air is still blown of the angled section of this T? (I hope I'm getting this right because I forgot to mark it.) When I tested earlier with a different DIY contraption, the air blew right out a 3inch pipe without any issues. In fact earlier, it was a 90 degree elbow only in the middle of the contraption, that too sucked the air but this one having given it so much space, it still blows out. What could be wrong here? This is also a concern as the piping of the blower and the exhaust connect here. A 45 degree will connect with the blower to the main exhaust piping and then the piping blow continues.
Many thanks for your time again
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I really do not understand your plan.Well thanks to each and everyone of you for your useful and helpful responses since my last post. I'd actually been busy trying and experimenting this past week on the setup that I'd to make especially in orientation with the airflow being sucked by the venturi as well as a pc exhaust fan.
Something that I think may have missed out by the members is the video I'd shared earlier that my setup is basically in the alley outside my house, so its not an enclosed lab but also not very open to perform these tasks safely. I live in the lower portion, there are owners living above, and there are neighbours just about everywhere
Henceforth, I built this
As marked :
1, BLUE : Pipe opening for the insertion of a blower
2, RED : Y-T as opening for the venturi air suction, tested over a beaker with hot water. Sucks good enough, but not much suction without the watch glass so some of it will escape and be caught by the exhaust
3, GREEN : 12v 4.5 amps blower with a PVC cup cut out on the bottom, to increase the length I tested it out with the tube of a tissue roll but that doesn't seem like a viable option when in full mode operation. Can someone give me a better idea for that please?
4, YELLOW : 12v 1.9 amps PC fan exhaust. (needs distance testing)
This setup will be enclosed with a glass or plexiglass from the front as doors. Although it just seems fine and not perfect per se, I'd like to see a feedback from you seniors.
Something I don't understand or make it out is as you can see the exhaust piping starts with a 6 inch coupling=>pipe=>6-4inch reducer=>4inch pipe=>then the Y-T. How come the air is still blown of the angled section of this T? (I hope I'm getting this right because I forgot to mark it.) When I tested earlier with a different DIY contraption, the air blew right out a 3inch pipe without any issues. In fact earlier, it was a 90 degree elbow only in the middle of the contraption, that too sucked the air but this one having given it so much space, it still blows out. What could be wrong here? This is also a concern as the piping of the blower and the exhaust connect here. A 45 degree will connect with the blower to the main exhaust piping and then the piping blow continues.
Many thanks for your time again
Where are you going to scrub your fumes?
What is the point with the opening in yellow and the pipes here?
The feed through pipe is what should have the main large fan with high through put.
On the outside on the left.
This do not make much sense for me at all.
Like I said earlier, I gave the setup too many tries but I just couldn't get the blower to bubble even the water bottle... let alone the other setup for it, so I decided to give up on that
The yellow opening is the fumehood exhaust other than blower. Since the blower wasn't that powerful for entire fumehood suction and just from the opening of the pipe as marked in red. I decided to install another fan for any fumes that don't go through the overhead opening. Both these pipes will connect where the Y-T can be seen and then an extension of the pipe will further go upward 9 feet for clearance. Hope this clears
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