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DrewFlu33

Handling Plastisol Fumes - Will my fume hood plan work?

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I did a lot of searching and could not find any discussion that quite gets at what I'm planning.  If I missed it please let me know!  Apologies in advance for the length of this as well, and many thanks to anyone willing to help a newbie!

The TL;DR (too long; didn't read) version: Will a 4" 203 CFM rated fan (6" 440 CFM rated fan)  adequately move fumes out of a 12 cubic foot "fume hood," and will I need to vent outside or will a charcoal filter would take care of those fumes?

After years of waffling, some discontinued baits have pushed me over the edge and I am getting into the soft plastics game.  I am in the process of planning out my setup right now.  I'll only be making baits for myself and friends, so I'm not going big by any stretch.  I have done a ton of research and given that my initial purchases are of single cavity molds or otherwise for small baits and I don't want to fight with constant reheats, my plan is to use a Fry Daddy / PID controller / DIY stirrer setup.  I have started piecing it together and really feel that this part will work nicely. 

The next step for me is figuring out how to work with plastisol during the Minnesota winter without the benefit of a heated garage.  This means I am planning to work inside my house (in the basement).  Obviously handling the fumes is a big concern.  After hours of research, I have put together a plan that I believe will work but figure that running my idea by the experts before putting it together as well as getting some input on a few remaining questions is probably a good idea!

I have seen some hood setups that guys have put together and know that getting adequate CFM becomes a huge concern in most of them where guys are positioning a hood over their work area.  Accordingly, they can get spendy quickly, not to mention the issue of dealing with runs of really large diameter ductwork.  Instead, I plan to enclose the work area so that I can concentrate the bad stuff to more efficiently get rid of it....

The Plan - an enclosed "fume hood" / box  (similar to what you might've used in a high school or college chemistry class) on top of a work bench

  • Approximately 3' W X 2' D x 2' H out of 3/8" plywood on the back, sides, and top
    • Seams caulked to seal as well as possible
    • Weather stripping around bottom of box to improve seal?
  • Front made out of plexiglass 
    • "Tracks" made out of furring strips to allow front to slide up and down (inside seams caulked)
    • Door latches as stoppers to hold plexiglass when working
    • Weather stripping on inside of plexiglass to seal gaps there
  • Moving air: Vent flange mounted to top of box with duct hose to inline fan
  • LEDs inside so I can see what I'm doing

Assuming this all sounds doable (and please let me know if it does not!), here's where I run into some questions. 

Fan/duct size and moving enough air:  I'm debating between a 4" fan rated to move 203 CFM of air, and a 6" fan rated to move 440 CFM of air.  I suspect these are "zero load" ratings, so anticipate actual performance to be less than this.  However, both are designed to be used in "grow tents" and users report easily creating negative pressure in their tents that are much larger than my box with both models.  Given that I really just need to do enough to get negative pressure inside the box so that the fumes are being pulled out of the vent, I think the smaller one should do the trick but honestly don't know.  I also believe the fumes should rise with the heat which should help me (since the opening I don't want them going out of would be at the bottom).  Would the 4"/203 CFM be adequate here, or should I just go with the bigger 6" /440 CFM ?  

Dumping the fumes:  My initial plan was to stick the downwind side of my duct hose out the window to vent it outside.  However, it turns out that the small window in my little basement shop does not open.  No idea how I'm just now discovering this, but I digress...   Instead, I've come across some charcoal filters that are placed on the terminal end of the ductwork that I think might work.  Do I need to cut a hole to vent outside / replace my window, or would the activated charcoal filter take care of the fumes?   

If the charcoal would take care of the fumes, I suspect it would restrict airflow more than an open-ended run of ducting would.  At the same time,  it would make dealing with large ductwork much easier since I'm not needing to go very far with it.  In that case, I feel that I could pretty easily step up to an 8" / 740 CFM fan if that's necessary. 

Links to the fan/charcoal filter setup I'm considering (the fans are also available without filters if I choose to vent outside): https://www.amazon.com/VIVOSUN-Inline-Control-Australia-Charcoal/dp/B07BS9XVQB

Thank you all for any guidance you can offer!

 

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Hmm. It’s a neat idea and I think your enclosure will work nice. One thing I think about is you need to replace the air you are exhausting with fresh air to create some flow and you can do that with some well placed ventilation holes or by creating a little space in your plexi. As you get into the soft plastics, another thing that comes to mind is the ability to do laminates and possibly two of your little fry daddies placed side by side so keep that in mind with whatever you are building. Two feet high isn’t enough room to work a couple pots and a twin injector. Probably not enough for a six inch single and a pot. And yes, you will want to go there more than likely as you progress in the hobby. 
 

I believe with an enclosed space your plan will work. Personally, I would vent to the outside as the plastisol can become quite strong especially if you burn some. Make your box a little larger and go with the 440cfm. That said, the 220 is moving almost 4cfm a second which should be fine in an enclosure. I’m no HVAC expert, though. JMO. 

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PS... I have a great fan for you... Maybe I could apply this towards the rods you built me... 

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Hey, I know you! And I still owe you a phone call about that! ;)

29 minutes ago, 21xdc said:

PS... I have a great fan for you... Maybe I could apply this towards the rods you built me... 

 

Edited by DrewFlu33
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3 hours ago, Apdriver said:

Hmm. It’s a neat idea and I think your enclosure will work nice. One thing I think about is you need to replace the air you are exhausting with fresh air to create some flow and you can do that with some well placed ventilation holes or by creating a little space in your plexi. As you get into the soft plastics, another thing that comes to mind is the ability to do laminates and possibly two of your little fry daddies placed side by side so keep that in mind with whatever you are building. Two feet high isn’t enough room to work a couple pots and a twin injector. Probably not enough for a six inch single and a pot. And yes, you will want to go there more than likely as you progress in the hobby. 
 

I believe with an enclosed space your plan will work. Personally, I would vent to the outside as the plastisol can become quite strong especially if you burn some. Make your box a little larger and go with the 440cfm. That said, the 220 is moving almost 4cfm a second which should be fine in an enclosure. I’m no HVAC expert, though. JMO. 

Really appreciate the insight!  Now that you mention it,  adding some extra room is  something I'll need to do.  I hadn't even thought about not having enough head room to work and two feet is probably cutting it close even with what I've got planned now, so I'll definitely need to add a little height.  Seems like it would make sense just to make it a foot taller and wider to be safe.  That might necessitate some cross-member support across the top, but that shouldn't be too big of a problem.    

As for allowing fresh air in, my thought was that I'd have the plexiglass slid up enough for me to reach in to be working on stuff, so that would allow fresh air in to replace the air being sucked out by the fan.  Skipping the weatherstripping around the bottom might be a good idea to allow enough air to seep in to avoid any issues if I've got the plexiglass down while things are heating up or whatever. 

Thanks again!

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