I’m currently thinking about building a small fume hood out of melamine with acrylic for the front. In my research it seems there’s two common methods of exhausting fumes and I’m curious about input from the community.
I intend to build a 4x4x2 (HxWxD) fume hood, my original plan was to use a 3 inch inline blower fan on a PWM controller to create negative pressure within the fume hood to exhaust out of 4 inch PVC pipe out of a window.
I’m now wondering if this is going to be enough or not. A 10 inch explosion proof fan and ducting is moderately more expensive but I feel may be worth the trade off for a more proven/safety oriented design.
Two questions I’d like input on from the community. Is the size of the fume hood adequate? I primarily envision using the hood when messing with any noxious solvents, possibly place the SPD or DCVC column inside. Practically I’m curious about input from the community.
Second question is the Venturi enough to even bother with? Or should i bite the bullet on a 10 or 12 inch explosion proof fan with PVC ducting; and if so, should i size the fan to the room or the fume hood - mostly thinking if it can serve a dual safety purpose (buy once - cry once; hopefully).
Agreed, though I don’t think they’re tall enough for my desires which drove me to the DIY route. I think explosion proof fan and grounded ducting is the path forward. I appreciate the input @drake@cyclopath
I do kind of like the idea of a fume hood large enough to sit in… I’ve got a 24x72 stainless steel table; Maybe build something that encapsulates that area…
Or a California Style fume hood. They are pretty cheap considering what they do and you can find them at used equipment sales.
Building your own… when your life and the lives of the people who are near you and work with you. Brave soul.
How you get it to pass codes that way?
But really - if you need it to be giant - then the walk-in style is the way to go.
If you need it to be bigger than that - probably best to consider closing all your loop. If the equipment is that big, it doesn’t need to be open. And just put smaller exhaust units around the places you want to open things, with plenty of air changes per hour in the space around that.
PVC is used often for broad range of resistance to the fumes. Are you putting some acids and bases in there too? Or what?
So you want at least 6 air changes per hour - probably way more. I don’t know the size of your room - but you can calculate the total volume of the room and then times that by how many times you want the air to leave the space. And then you can buy an appropriately chemical resistance, potentially sparkless motor to fit your needs.
Don’t forget that you’ll need to put that much air back into the room/space as well. Or things like doors and stuff will be super hard to open.
If you are going with an enclosure with ventilation - you want the face velocity to be like 50fpm sometimes more (you’ll have a local code for this) and you can calculate that as well, so you know what size fan to get.
But really - you should be able to get one used or new for less than 10k. And it will be safer than just guessing.
Thanks for your input! I think you may misunderstand my scale. I’m doing this at a personal scale.
If this ever becomes a money making endeavor (and who knows, maybe it will), I would be more concerned with this.
At this time I’m trying to do something as safely as I reasonably can be in a home setting.
It appears 100-200 fpm is recommended depending on the chemicals in use, I’ll have to take this into consideration given the fan is rated for 55 cubic meters per minute. I have a PAPR with CBNR filters along with chemical resistant elbow length gloves (I haven’t committed to the full coverall just yet but will probably grab a pair…) for the really nasty stuff.
Total volume of the room is roughly 2016 cubic feet, which means the 10 inch fan would only be able to change air out for the entire room once per minute? Seems reasonable.
I appreciate you mentioning this, I’m aware and haven’t found an appealing solution yet. One that balances aesthetics in a home with function. Might just be time to pop a HVAC grate into the door…
As a side question. I’m getting 30 gallon safety cabinet to store all the chemicals in. Is it necessary to surround the cabinet with fire board? Not sure exactly what might happen in the event of a chemical fire inside the cabinet. Any reason i shouldn’t keep something like this in there?
Get one that is rated for 4 hours (they exist). Make sure its grounded and has appropriate venting (it will tell you if it needs it, you vent it through the same ducting). They are designed to keep the fire inside (they will get hot, so you know, don’t store stuff around it…) but you don’t need to surround it in other stuff. By don’t need I mean - if you were in a building that you were also not living in, this would not be a requirement. In your home… I’d probably put in the garage, assuming you have a to code garage, cause then you’ll have a fire wall between your house and the garage (but don’t add a vent to that door, cause then the fire wall will lose its integrity…)
I’ve found that an open window helps with air flow - you are pulling from the outside, so make sure its open enough. And if you cannot get an open window - then do the same size intake fan through a wall or ceiling port. You don’t have to leave it on all the time (cause you know heating and cooling) only when you have the “sash” open on your hood.
You can go 100-200 - but most places only require 50-60ish to meet codes.
I haven’t ever used on of those automatic discharge extinguishers, so I don’t know about that.
But really - if your flammable cabinet catches fire AND you cannot get a fire department to come and put it out in 4 hours… something is really wrong probably. Labconco has desktop sized hoods on the cheap, and there are used ones as well. And they come with fan specs, certification for flow rates, if you want those. I’ve used Hemco as well (midwestern brand, I like them.)
I cannot wait to see what you decide to go with. Please let me know. <3
I think you need to be more specific. What do you actually plan on producing? Judging by your first post you’re jumping to scrapping together a makeshift fume hood with a $50 fan before knowing what you actually plan on doing as far as solvents, volume, etc. What you’re handling makes all the difference on what you need to use for a setup. If a 12” spark proof fan is out of your budget then I’m going to go out on a limb and say that you probably should hold off on handling any solvents.
I’m not quite sure why you’re making all these assumptions when it’s largely already been addressed earlier in the thread.
What differences are the solvents going to make in the function of a fume hood? Storage is one thing, but we’re talking about evacuating the air in a ~64 cubic foot space, which per:
Again I don’t understand the assumptions made when inference should show you otherwise.
The 400lb explosion proof box with automatic discharge fire extinguisher is 7x the cost of the fan. I don’t know why you felt the need to bring up a point about money.
I take my safety very seriously, that should be obvious from the precautions I’ve outlined above (explosion proof cabinet, automatic fire extinguishers, originally a Venturi design - used in fume hoods, PAPR, chemical resistant gloves and clothing; unmentioned - eye washing station, SDS on the wall, chemical sensors for noxious gases). If I’m missing something please inform me, that’s why I’m here and why I posted the question. Truth be told I don’t see where you tried to help, it seems you wanted to end up on “budget” and to encourage me to stay away…
I just really don’t understand how you could read the conversation above and come away with your response.
<3