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Author: Subject: Fume Hood Construction
CouchHatter
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[*] posted on 27-6-2019 at 17:45


Here is my completed fume hood. I finally installed the stack on the roof and it is functional! I am done painting for a while, something like 10-15 sessions to get all the parts covered. Ugh.

Sometime I'll make a thread to showcase all the bells and whistles and its construction.

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Ubya
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[*] posted on 28-6-2019 at 03:18


@CouchHatter pretty cool, and big! but what about that horizontal sash? never seen a fumehood using this type of design, is it effective?




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Abromination
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[*] posted on 6-7-2019 at 14:44


Nice hood, but strange sash design.

Anyways, I am working on my own hood right now and would like to know what y’all would suggest I do for baffle dimensions. My hood is 30 inches wide, 28 tall and 18 inches from the front of the actual opening to the very back. Sorry for using inches, I would have preferred not too.
I am using a 500cfm fan.

I’m not sure how much it matters with such a strong fan but it would be nice to have them anyways.



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CouchHatter
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[*] posted on 7-7-2019 at 17:39


It's 5' x 5' x 2'. No one ever said "I wish I made it smaller!":D I haven't seen a horizontal sash in use either, but it was addressed in Laboratory Fume Hoods: A User's Manual. I already owned the tempered window panes and simply cut another frame I had to size. So even if it goes in the bin I'm not out much... I can work around the large panes without sticking my head in, but qualitative testing will determine if it gets replaced with a more conventional solution, or not.

That was only one of the resources I used to design my hood. It was written in 1993 and I didn't really cross-check the horizontal sash thing with other books, so I will surely test it before using it much. Water is pulled 3/8" through a 3/16" ID tubing though, and the face velocity seems to be excellent. It completely removed the smoke from a tiny smoke bomb ~8 inches outside the hood. Now that firework season is over, I have a supply of bigger smoke bombs to really put it to the test. Just need some extra time.

Abromination, how wide is your duct? Look at page 21-22. The only dimension I would change would be the middle Slot B, to make it more close to the bottom third of the hood.

back baffle design p16-23

sash varieties p22-27


I made the pages barely too big so I'm just linking them in lieu of the 8MB attachment limit here.
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Abromination
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[*] posted on 8-7-2019 at 12:57


Quote: Originally posted by CouchHatter  
It's 5' x 5' x 2'. No one ever said "I wish I made it smaller!":D I haven't seen a horizontal sash in use either, but it was addressed in Laboratory Fume Hoods: A User's Manual. I already owned the tempered window panes and simply cut another frame I had to size. So even if it goes in the bin I'm not out much... I can work around the large panes without sticking my head in, but qualitative testing will determine if it gets replaced with a more conventional solution, or not.

That was only one of the resources I used to design my hood. It was written in 1993 and I didn't really cross-check the horizontal sash thing with other books, so I will surely test it before using it much. Water is pulled 3/8" through a 3/16" ID tubing though, and the face velocity seems to be excellent. It completely removed the smoke from a tiny smoke bomb ~8 inches outside the hood. Now that firework season is over, I have a supply of bigger smoke bombs to really put it to the test. Just need some extra time.

Abromination, how wide is your duct? Look at page 21-22. The only dimension I would change would be the middle Slot B, to make it more close to the bottom third of the hood.

back baffle design p16-23

sash varieties p22-27


I made the pages barely too big so I'm just linking them in lieu of the 8MB attachment limit here.


Here are the two real blower options I am looking at:
https://www.amazon.com/Fasco-A455-Centrifugal-Blower-Bearing...

https://www.amazon.com/gp/aw/d/B01MTFZSP5/ref=cm_cr_arp_mb_b...

I probably wont get the seaflow one, and the first fasco one doesn’t give me the input or output diameters.


The information on the baffles was super useful, that will be the next step after I install the sash.
Thank you, mate




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Abromination
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[*] posted on 19-7-2019 at 09:55


The first baffle and lighting has been installed and I have decided on what blower I want. I know that in professional labs that the blower is connected directly to the outside plenum, but is this better then installing it directly onto the hood body?

I put some regularly used equipment in to get a better feeling about space inside of the hood.

Next project is the sash and the control panel.

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List of materials made by ScienceMadness.org users:
https://docs.google.com/spreadsheets/d/1nmJ8uq-h4IkXPxD5svnT...
--------------------------------
Elements Collected: H, Li, C, N, O, Mg, Al, Si, P, S, Fe, Ni, Cu, Zn, Ag, I, Au, Pb, Bi, Am
Last Acquired: Bi
Next: B
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CouchHatter
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[*] posted on 20-7-2019 at 09:16


Looking good Abromination! Though I fear for that sep funnel's life, never seen one held that way:P

There is a chapter about duct work... I think ear comfort, multiple hoods, and vibration are why it's done that way professionally. The most important reason I can think of, though, is so that there's no positive pressure in your duct.

Having the blower directly after the hood means that any tiny hole or crevice in the duct after the blower will push air into the room and not be exhausted.

Having the blower as close as possible to the end of the duct means that everywhere before the blower is under suction, and that even if there are small gaps in your duct, it will only imperceptibly lessen your air velocity.

As long as you're certain that everything after the blower is airtight, and are certain the dB levels won't be an issue for constant use, and don't set loose things in the hood that might vibrate around, I'd say it's an option.

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Abromination
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[*] posted on 20-7-2019 at 13:54


Quote: Originally posted by CouchHatter  
Looking good Abromination! Though I fear for that sep funnel's life, never seen one held that way:P

There is a chapter about duct work... I think ear comfort, multiple hoods, and vibration are why it's done that way professionally. The most important reason I can think of, though, is so that there's no positive pressure in your duct.

Having the blower directly after the hood means that any tiny hole or crevice in the duct after the blower will push air into the room and not be exhausted.

Having the blower as close as possible to the end of the duct means that everywhere before the blower is under suction, and that even if there are small gaps in your duct, it will only imperceptibly lessen your air velocity.

As long as you're certain that everything after the blower is airtight, and are certain the dB levels won't be an issue for constant use, and don't set loose things in the hood that might vibrate around, I'd say it's an option.



Don’t worry, it’s quite stable and easier to manipulate with the clamps I have, there is a wide joint at the bottom :)
I will be putting the blower on the end of the duct, which will also help with noise. Thanks again for your help!




List of materials made by ScienceMadness.org users:
https://docs.google.com/spreadsheets/d/1nmJ8uq-h4IkXPxD5svnT...
--------------------------------
Elements Collected: H, Li, C, N, O, Mg, Al, Si, P, S, Fe, Ni, Cu, Zn, Ag, I, Au, Pb, Bi, Am
Last Acquired: Bi
Next: B
--------------
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