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.
A gallery of home built hoods and fume scrubbers _hood_
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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.
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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
Attachments
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
You really do not understand this.
The bottles are NOT used with blowers but a vacuum source.
The vacuum source are supplied by either a mechanical pump or an eductor (Venturi system).
https://marineengineeringonline.com/operation-maintenance-eductor-ships/
https://en.wikipedia.org/wiki/Vacuum_ejector
For creating a proper venturi system you need a powerful high volume fan that blows past the suction pipe.
And there are no upsides on letting it go through the hood as it will occupy a lot of space.
Let it go behind the hood or what ever fits the area.
But since you are on the "street" you NEED a scrubber and a stable power source, you and the surroundings need to be safe if the power disappears.
Different possible configurations:
Different routes different color
Edit one illustration was wrong
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I'll admit it, you're quite right I did not. Since we use an air bubbler for aeration I thought this was just supposed to be an extension of the same concept. This means that I wasted a lot of my time after something that wasn't going to work in the first place. A HUGE conceptual error. lesson learnt. But on the other hand I also do not understand ; do we connect the blower pipe directly to the bottle and then the vacuum extracts it from the other end? Is that how it goes?
The piping goes as long as 14ft, post blowing. SO I read the fumes would dissipate by the time it reaches the clearance point by 15-20 ft. Hence the plan. Below is the diagram of my plan, although I directly shared the real life picture but I thought Ill share this one too. It is somewhat close to your 3rd image.
The suction works fine through the single inlet inside the hood. This is how the end result would be
Attachments
That depends entirely on what you do.
A Cupric Chloride leach or simple HCl it will do.
For NOx it is not sufficient, that is why I suggested the flask train.
Or you need a scrubber of sorts.
The flask train is driven by by a proper vacuum system, either with an e-ductor system or a real vacuum pump.
The e-ductor system is cheapest and will last the longest.
It can be driven by a sufficient water flow either directly or if that is not available, a tank with a water pump circulating the water.
I still do not understand why you plan a dual system.
You either use a Venturi system or a direct system, both are not necessary.
The rest fumes from the flask train will go into the water tank, if there is any fumes at all.
It may require some time for further flask train experimentations, bearing in mind the technique you have mentioned.
I cant refill the holes again. Please let me know if it still seems feasible. And there are too many scrubber posts, which of those would help me in this situation?
Thanks
I hadn't thought a small venturi setup could take care of an entire hood given the size so a dual system was always in play. Be it with a scrubber or without, Now Ive already carved a couple of holes as can be seen... Is a scrubber with only the blower (overhead pipe) still an attachable/ operational option? If yes, I'll hold onto my current venture as that is my first priority. Will carry out experiments for an understanding and proceed from there.
I cant refill the holes again. Please let me know if it still seems feasible. And there are too many scrubber posts, which of those would help me in this situation?
Thanks
I'd start looking in the build your own equipment section.
Hello sir,
My mind this past week had been so clogged that I completely missed this one and now I think this is probably the closest of how I can imagine my setup to be like given what I have already built.
I do have questions here :
1, The overhead blower does not seem to be connected to the red pipes, so what is its main purposes here? the regular fumes of the hood only?
2, The red pipe does not have any suction or blowing therein as can be seen, so is the science of the entire unit being taken care of by that lone pump at the bottom right end only?
3, 'The blue line is vacuum and is selected at the valve by the vacuum generator. Each 1/2" vacuum port needs a shut off valve and a PVC barbed fitting.' I really don't understand if this would be needed... I would be highly grateful for your response as I'm brain cooked at this point of trying to make this thing work properly.
Many thanks in advance.
The overhead pipe (black in the drawing) is for what the EPA refers to as fugitive emission, it is separate from the scrubbed emission which is indicated with the red pipes.
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The red pipe is powered by a venturi (actually a water powered venturi also called an eductor). The eductor is powered by the pump which recirculates water through the eductor to generate suction which transferred into the red pipe.
