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Need advice for air filtration system for paint, resin


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Such as brands, cost, models, what system are you personally using ? Please share some photos of your system and scale modeling workshop :)

 

I am looking to set up something that throws all the fumes outside and filter them at the same time, HEPA filters, activated charcoal filter, in whatever combination and set up work best and is safe (need fans that are explosion proof would be my guess ?). I will also obviously need a flexible hose, maybe two (any suggestions for sources, types of hoses ?). I will most likely end up painting the outside of the hoses in a way to make them more esthetically pleasing to keep my wife happy and not turn the place into a totally industrial looking place :p (little flowers or something).

 

Then I'll have to figure out a way to design this in a way that will keep critters (and people) as well as dust from the outside out (and the cold in winter) and which cannot be vandalized so easily  (the outlet, and inlet as well if I use both together). Plus a way to lock the guillotine window plus the set up that will hold the outlet plus inlet together (it's kind of a long window) in place safely so the window cannot be opened from the outside, because I am looking at making this more or less 'permanent', sort of, but removable without any or little change to the existing window structure.

 

Any ideas and suggestions from modelers who already have their own set-up in an appartement ?

 

Stephane. 

 

 

 

Edited by Stratospheremodels
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The system that I've used for almost thirty years consists of the following.  A fabricated paint booth with a built in extraction fan (standard commercial issue).  The fan is connected to a one-way dryer vent mounted on sheet of plywood cut to fit one of the basement window frames.  When living in an apartment, the window piece could be removed allowing the window to close.  Before someone drops in about the system not being enough, the design was worked out by myself and co-worker both of us having extensive experience in environmental engineering.

 

Looking at what you posted, in my opinion, you are over killing the problem of venting your work area.  If you really want to go to the max, investigate getting a hepa filter exhaust machine like those used by environmental remediation contractors.  FYI, these units run in the two to four thousand dollar range.  If you really feel the need for filtration, you could use a hepa filter combined with an organic vapor filter to take care of the particulates and VOCs running through the system.  These filter packs are available in cannisters sized to fit various sizes of round duct or flex tube.  If going that route, plan of a larger capacity exhaust fan to deal with the back pressure generated by the filter packs.  Again, unless you are doing high volumn painting, the amount of fumes generated for extraction will be well below that requiring filtration.  If you feel need to determine how much filtration is needed get a couple of air samples at your exhaust outlet and have them analyzed against your local air quality regulations.

 

I don't mean to down play your concerns, however  a career in environmental engineering tells me that modelers tend to overestimate just how much "polution" we putting out.  Feel free to contact me off board if you want to discuss this further or need more information.

 

Best wishes, Dave

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An after thought to this discussion.  Painting our models and to a lesser extent sanding/grinding resin parts generates a waste stream the discharge of which has a (very minor) environmental impact that we want to mitigate usually by some form of filtration.  Most people jump towards a HEPA filter mostly because that is what we hear about all the time.  HEPA filters are High Efficiency PARTICULATE Air filters.  The key word being Particulate.  The biggest part of our waste stream are the paint vapors which contain minimal particulates but very high quantities Volatile Organic Chemicals (VOCs.)  Removing the VOCs from our waste stream is pretty easy, simply use an Organic Vapor filter instead of a HEPA filter.  Should you be generating huge amounts of resin dust for some reason simply add the HEPA filter back into the package.  So now we have mitigated our original waste stream and run into a problem that most of us are not aware of.  We have generated a secondary waste stream that has to be dealt with for disposal.  That waste stream being the used, contaminated air filters.  Many jurisdictions, including the state I live in are pretty stringent on the disposal of paint by products containing VOCs.  Disposal of unused paint, cans, paint rags, or anything else saturated with VOCs can NOT be dumped in a public trash dump and are required to be delivered to a Hazardous Materials disposal site.  So, in designing our paint booth ventilation system, we need to decide if we are simply dissipating the odors or really mitigating an environmental impact.  If the answer is just getting rid of the odors, a simple exhaust system with out  filtration will work fine plus mitigate the environmental issue by diluting the VOCs with a large mass of moving air.

 

Sorry if this is beginning to sound like an Environmental Engineering 101 paper, but the reality is, the basic principles in ventilating our paint booths and designing "Stack Scrubbers" for a petroleum refinery are pretty much the same.  And for my part, if I never see another stack scrubber specification again, life will be good.

 

HTH, Dave

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Hi Dave, 

 

Thank you for your very detailed and enlightening answer ! In fact I don't mind the environmental engineering 101 course,  the more info the better. 

 

I was probably thinking about a system that can do everything / both paint and remove fumes from resin manufacturing (no matter what the method, and some of those methods cannot be contained in a pressure pot). I don't do much paint anymore, quite rare, but from time to time I will need to prime or even fully paint models for the purpose of showing pictures online. Filtering resin fumes (of varied types) would be the main use, thus I was thinking I would need activated charcoal. I have seen machines from a company from the UK that sell industry certified air filtration machines dedicated to removing VOC'S. I think the smallest machine was around 700$US or more. The next slightly bigger machine was well above 1200$... So I thought I'd try to build my own system. They say they use 3 stage filtration, including activated charcoal and HEPA (?) filter. I can't remember what was the 3rd stage.

 

Now that I remember,  many years ago when I used to do airbrush illustration, there was an art store in New York that sold balls of a ceramic/clay like material that would filter airbrush spray from the air (you'd just fill a jar with them and put it near your work table). Years later i found out what this material was: molecular sieves. Could that also be used in combination with a homebuilt system like we are talking about ? I do know however that you have to select a molecular sieve that's specifically tailored for the molecule of a specific VOC you want to block, similar to what the oil industry uses for refining. Please correct me if I'm wrong. So that maybe impractical and potentially more costly than using filters and charcoal ?.

 

Since the fumes are potentially flammable (a lot of resin vapors are) that's why I was thinking about using a ventilator fan with a spark proof electric motor. My guess is that those that are included with commercial paint booths are.

 

Now I remember why this manufacturer from the UK was using HEPA filters : that's because there was some nano size particles generated by some of the applications for which their filtration machines were being used. It involved hot plastics. Then thst makes sense. Given that my system will be mutifunction though, I will need to filter resin VOC's, paint, and maybe at some point nano particles from heat 3D plastics. So my guess is that I will still need that HEPA filter.

 

It is not so much the odors (though there is that too obviously) so much as the solvents and potentially harmful VOC's in the various products I want to filter which I worry more about. Even silicones can be a concern (there is a lot of methyl in there that evaporates as the material cures).

 

Basically I want to bring as close to zero as possible the emission of VOC''s to be on the safe side as some systems I will use emit VOC's during hours. In fact some resin parts take over 14 hours to degas. I even experienced 2 weeks time to degas for some system which thankfully I no longer use since 15 years.

 

Given that I don't want to just dump unfiltered fumes outside due to concern for others, I have to have the full filtration system  (both for VOC's and for particulate (paint, etc, when I will use them), but the main use will be to filter the solvents & other VOC's. And also so that these don't come back inside the room as a lot of VOC's of products I will use are heavier than air and I am located in a half-basement.

 

Stephane 

Edited by Stratospheremodels
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Stephane, looking at the description of what your end use will be, I would suggest finding a pre-made unit like the one you are describing.  In the filter package, the HEPA filter will contain the particulate solids, the charcoal filter neutralizes the odors and the third filter is probably organic vapor to catch the VOCs.  You might want to do some cost estimating on what it would take to purchase the needed filter package, and intrinsicaly safe fan (non-explosive) tubing, etc, to fabricate your own unit against the cost of a pre-fabricated unit.  Since it sounds like you are running a commercial enterprise, I would go with the commercial unit,  especially, if it comes with a certification.    As far a the passive filtration (clay jars) I doubt that is the solution you are looking for.   HTH, Dave

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Hi Dave,

 

Thank you, my guess is that paint fumes and paint solvents are most likely nastier than any of the resins I would want to filter for (particularly petroleum based paints). Given that I don't use any aliphatic resins (so that removes the nasty stuff) nor anything that's higher up in the health safety scale (I mostly use the mild stuff), I think I would be fine with a homemade unit (given that my budget is zero to get a commercial unit). In fact the UK made filtration systems are quite simple boxes but in my opinion overpriced for what they are (just square metal boxes with a removable top held with a metal latch and filters snd fan(s) inside). They do have variable speed control and some lights on them to indicate the speed, which is the only thing i think why the price is high (plus being made in the UK) but otherwise I think they probably have very simple systems inside). In fact, even for the price they do not include the inlets (you have to 3D print them yourself). I think if i do mine without any fancy electronics and just a single speed and fairly simple wood box or some other material and good sealing/gaskets (caulking silicone, maybe even 3D printed custom gaskets if needed or just making custom ones with cast silicone out of a routed shape in a plastic sheet, I will have a tightly sealed unit).

 

There have been studies that found out that FDM printers emit nano particles (a bit similar to the pollutants emitted by diesel engines) and other carcinogens (a lot of people have these machines at home these days) but they found out that a combination of an enclosure plus low temperature is enough to contain 99% or more of the emissions. Given that I don't plan to have an FDM printer for quite a while but I might eventually get one, that's partly why I looked at those UK made filtration systems (the smallest one was designed for desktop FDM printers).

 

I think spark proof fans should not be too hard to source, given that hobby scale paint booths no doubt use such fans already. I've seen a bunch of Japanese half- home made filtration systems/vents for paint and or resin, and they were featured in scale modeling magazines, so I guess if they didn't catch on fire their set ups seem to be good. Some had particulate filters but others were just a paint booth connected to an air hose for dryers and a fan or 2. Too bad I don't read Japanese. But the articles seemed rather lacking on technical info, they were more a display of who is using what in is own scale modeling corner. Some of the modelers were combining both resin casting and spray painting. My own unit will be more elaborate than that, to be on the safe side. Haven't decided yet if it will be similar to your own unit (plus charcoal & HEPA filters added) or as a unit similar to the UK machine. 

 

Anyone's got photos to share of their own set ups ?

 

Stephane 

Stratosphere Models 

Website : http://www.picturetrail.com/stratospheremodels

Edited by Stratospheremodels
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