Charcoal filter

Now that I have an enclosure around my i3 and have brought my printers indoors as its too cold to print in the workshop outbuilding, ABS fumes are now an issue. I have thought about a proper fume vent but this means having a window open or drilling a big hole in my house. Would a charcoal filter work to filter ABS fumes? This would be much easier than an external vent.

The primary issue is the really tiny toxic particles that are emitted.

You can read about filters here. I designed a multi-stage filter, even got the parts, but didn't build it as I moved my printer outside my office to an area with an exhaust fan, and so I didn't need it... There are some options others found in that thread as well, using respirator filters.

Hope that helps!

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
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What about just using a commercially available hepa replacement filters with a fan? The hepa air purifiers are just a fan with a pre filter (catches the larger particles so they don't clog up the hepa) and a hepa filter.

Just thought of something else. The portable air conditioners have a sliding window vent that fit most any window (they slide to make them larger) and have a nice vent. This allows the AC to vent out but still keep the window closed up against the vent.
[www.livingdirect.com]

Printing with PETG could be an alternative. [reprapworld.com]

I print with ABS all the time. My printer is completely enclosed, including clear polycarbonate on 3 sides, and is nearly air tight. When I'm printing I do not see anything resembling smoke inside the enclosure. I do prints that run for 15 hours regularly. If there were particles being omitted, after a 15 hour print I would expect to see the build chamber filled with smoke, yet it looks exactly the same as when the print started. I have a green laser that I shoot through the box - a green laser will cause even air molecules to light up enough to see the beam even in a particle free environment. When I shine the green laser through the printer's enclosure, I don't see the beam. If there were any particles in there, they should become visible that way.

I'm not saying there are no particles omitted, but I think there are far fewer particles than the people who write articles about it would have you believe.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Some articles suggest particle sizes down to the nanometer scale so whether they would show up even under laser light, unless the concentration was very high, is doubtful. However I do agree with you that's it's probably much less of a problem than many suggest. I have a smoke shutoff system in the enclosure and it has never triggered even on its most sensitive setting even during long prints,but maybe the particles are too fine it is optical like your laser.

But... I might print a tube to contain a coarse filter, charcoal beads and then a hepa filter with a low speed fan to draw air out of the enclosure. I will weight it accurately before installing and then see how much the hepa filter increases in mass (I'd expect the dust etc to collect on the coarse filter). It will be interesting to see if I can smell abs fumes during printing coming out of the vent.

Might try petg sure but I'm quite happy with abs for a lot of things I print it is a very useful material for a variety of reasons.

The air vent is a great idea. If you can't find one separately you could probably make one with a piece of wood and a plumbing fitting (or print an adapter).

Note that particles below 40 micron are not visible.

A HEPA filter should work fine! A true HEPA filter should indicate 99.97% at .3 micron.

I was so wrong about this.
I thought that HEPA filters would be less efficient at lower particle sizes, however the opposite is true, due to a different filtering mechanism that takes over for very small particles. Google HEPA filter efficiency curve.

It is important to realize the way a HEPA filter works:
- There is a sharp dip where it allows the most particles through, around .2 to .3 micron - and at that dip it captures 99.97% or more.
- Above and below that dip it doesn't pass more particles, it passes less!
- So at the .1 micron size that we are most concerned with, it passes much less than 99.95%. This is very good news.


This is from this link, especially see note 1.

This site calculates the efficiency at each particle size.
He is comparing the efficiency of one fiber, vs a low efficiency filter, vs a HEPA filter. Here is the data for the different particle sizes. I've highlighted the relevant particle sizes:



Note also:
- Filter efficiency goes up over time as long as the filter does not leak.
- Filtering performance goes up with lower velocity.
All good things.

It might be a good idea to use a pre-filter like a carbon filter to keep the HEPA filter from plugging up as quickly. May not matter however depending on the duty cycle.

Edited 1 time(s). Last edit at 01/02/2016 01:54PM by Paul Wanamaker.

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
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Decide for yourself.

Here's the info that is most sited about the particles emitted:

Particle emissions from 3D printers

Edit:

The raw study which talks about other plastics as well

How Toxic Are ABS & PLA Fumes?

Fact Sheet from Carnegie Mellon University

3D printing: Are there particles? How about fumes?

Edited 1 time(s). Last edit at 01/02/2016 03:32PM by Paul Wanamaker.

... I've assembled my first carbon filters for a CO2-laser from three comercial fryer filters stacked together and placed in a tube with two big PC fans, sucking the air through and venting through the next window out.

Actually I'm using a comercial laser fume absorber (fleece pre-filter and a really big box full with activated charcoal granules) running at the minimum throughput of around 30% for less noise ... could be I'll resolder the controller to get down to 10%, as it's more than enough for my lasers ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Respirator filters of about 60mm diameter are available very cheaply on ebay and aliexpress. Coupled with a 60mm blower fan it should be possible to rig a very simple scrubber for under $20. It's not going to compare with the hepa/ulpa filters, but I think I'll give it a try for something cheap and cheerful that should at least help.

And some solutions I found:

How to make a fume exhaust port
A scrubber on Thingiverse using a respirator filter.

Edit:
Note that a filter rated P100 has the same efficiency as HEPA, 99.97%. Here is one example, there are bound to be cheaper ones. They use little filter pads on top to get the 99.97% rating. I'll bet you could just use one of those pads and a carbon filter of your own making... Cheaper yet, but you'd have to take time to engineer it...

Note that a blower fan will deliver 2x to 3x the CFM at about the same DB rating, so it could be turned down further. Just another option.

Edited 1 time(s). Last edit at 01/02/2016 05:36PM by Paul Wanamaker.

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!

I have decided to rig up a respirator filter system for myself. Question is, would you vent it into the room or would you just recirculate it into the closed box?

If you vent it into the room that means the box would be pulling in cold air from outside (with ABS hot air is the whole reason for having a heated chamber after all) so this might cause issues. If you circulate it back into the box you are basically making it like a miniature air filter like you would use in your house.

Would there be any up side to venting the clean air back into the room?

What would you do?

If you read through the Thingiverse info he talks about how he has improved his design, to exhaust, so that his printer has a slight negative pressure (it must be well enclosed). That will help keep most of the 200 million particles per second from escaping.

If you are worried about too much air being drawn in, you could always only vent part, and recirculate the rest, or make the enclosure tighter.

Please let us know what you come up with.

And Thanks

Edited 1 time(s). Last edit at 01/05/2016 01:47AM by Paul Wanamaker.

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
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Quote
tmorris9
What would you do?

I plan to recirculate with a relatively low flow rate - I don't think you need a huge flow to scrub in a recirculating system of relatively low volume. The fan/filter package will sit high on the rear wall and so draw in hot air from the top of the enclosure. The duct will run down the outside back of the enclosure and return air below the level of the bed, hopefully avoiding any direct drafts onto the print. I'm also hoping the high/low duct route will help reduce the temperature gradient within the enclosure. The duct will also have an adjustable vent to allow part of the filtered air to escape into the room. By controlling the size of the vent I should be able to balance total flow with a little negative pressure to prevent unwanted leaks from the enclosure. I've also ordered a PWM fan controller to adjust the total flow/noise level.

Looking forward to trying it out, but need to build an enclosure first!

Well, that's a simple approach, but it doesn't count until someone has made it

I think it would be worth adding some sort of filter for particulates.

I like your idea James of a low flow recirculator, I have a small fan to blow hot air downwards in my enclosure anyway and a system such as the one your describe above just takes the place of this fan and hopefully provides a bit of additional peace of mind. It will be interesting to see what accumulates in the filters over time.

Well, I made one using the mask filter and the fan shown. Unfortunately there is zero air flow through the filter, the fan just does not have enough static pressure.

So I found a Noctura 120mm fan with 4mm H2O (highest I could find without going to PWM fans) and I used a Bissel exhaust round hepa filter so I had a fairly large surface area. Made a coupler to put the 2 together with an air tight seal and.... Zero air flow through the filter.

These case fans just don't have the pressure needed to pass through a proper filter. I am not giving up though, when I get some free time I am going to start researching pressure fans of other types until I find something appropriate for the job.



Edited 1 time(s). Last edit at 01/10/2016 07:16PM by tmorris9.

Well, that's an interesting result, albeit not the one we would have hoped for. For the record (and those that follow this thread later), which fans did you try?

The one I ordered is the Delta TFB0612GHE

[www.ebay.ca]

According to the manufacturer's datasheet it's rated for a max pressure of 31 mm/h2o, but of course there's zero flow at max pressure. Here's hoping it will do something useful, but I may have underestimated how restrictive the filters are. I guess we can parallel a few up to reduce resistance, but that makes it significantly more challenging to make.

I used the Nocture NF-F12 industrialPPC-2000 (note the same model number also has PWM versions). I would be interested to see what you find out since the highest pressure I could find in a 120mm (the larger the size the higher pressure you can get) was like 10mm H2O but that was the pwm version. I notice that fan looks extra thick, that might be an advantage for pressure.

Have you built yours yet? Any airflow? I just used a simple tissue in front of the filter to see if I had anything but it did not move any at all.



Edited 1 time(s). Last edit at 01/10/2016 07:34PM by tmorris9.

I'm currently using a hairdryer to heat my chamber and wondered if the fan in the hairdryer would be enough to move air through these filters? This would kill two birds with one stone as I could pull air from the top of the enclosure through the hairdryer down through the filters and duct it into the base of the chamber? Or perhaps have the filters before the hairdryer so keeping the particulates and fumes out of my hairdryer and avoiding passing them over its heater coils.

Heating, filtration and air recirculation in one assembly.

I suppose it'll have to be a case of build it and see if it works but a hairdryer can inflate an air mattress so it can move some air.

Edited 1 time(s). Last edit at 01/13/2016 06:42AM by DjDemonD.

That's a really neat idea, but I'd be very cautious about running the heating element - they're designed to run with a free flow of air, and when restricted by the filter it could overheat and be a fire risk. I sure hope we can find a fan solution that's a bit less noisy than the typical hair dryer though!

Yeah it is noisy but not too bad, it only cycles on every now and again when the heatbed and extruder are heated and the enclosure door is closed. It might be a tad less noisy built into what I have in mind. Its got a thermal cutout built in so the heating element should go off if it overheats, I'll test it. Still not sure if it will pull air through the filters but am considering this type of filter: hepa filter as it should allow more air flow and require a less powerful fan than the circular type. Also with it being a recirculating system the pressure is off to ensure everything is internally perfectly sealed in the filtration system, as the particulates/fumes will have multiple passes over any reasonable period of time.

Looks good for the particulates, might need something extra for the volatiles. Look forward to hearing how it goes. I sure wish my fan & filter would hurry up and get here - the downside to buying everything from China!

I'm intending to have a foam prefilter then this hepa unit possibly filled with activated charcoal beads. I'm hoping this will be adequate if I can get reasonable air flow through it.

Edited 1 time(s). Last edit at 01/13/2016 01:48PM by DjDemonD.

I found this hair dryer from Amazon that is supposed to have a centrifugal fan, and said to be quieter Revlon RVDR5045 Quiet pro Ionic Dryer

In a very fetching pink too that'll brighten up my printer.

I built a air filtration system that uses a filter from a vacuum cleaner (which is made with HEPA filter material, but that doesn't guarantee that it's HEPA because the folds can degrade the material's performance) followed by a bed of activated carbon granules sitting on a HEPA layer extracted from a surgical mask.

I used a 120mm x 120mm PC case cooler fan. I tried a generic fan from my local Best Buy, and with the carbon bed in place there was virtually no air flow that I could detect.

So from there I went to the most powerful fan in this configuration I could find (this: ). This gave me a decent flow, but it was far too noisy. One I'd build an enclosure was to reduce the noise, and so not wake my baby up when I'm printing.

From there I backed off the a slightly less powerful fan that's acceptable quiet. However, now I can only just about detect the air flow coming through if I have the carbon bed in place. Perhaps I could cut down the amount of carbon, or switch the surgical mask material for something else, but I've been using it without that last filter stage.

I print using PLA most the time so I'm not concerned about smells, but I am concerned about airborne particulate matter in my home.

I am hoping that low air flow won't be a problem in a recircating system as long as there is some flow the air will move through the filter eventually.

There are powered face mask type respirators, these use a "HE" High Efficiency type filter cartridge. I've never used one but I assume they would have better airflow, they are pricey tho, so maybe not a good option.
I could not find specifications for the small blowers that are used, other than they put out a minimum of 4 CFM.

Been thinking about other blowers, I'm wondering if a hand vacuum motor would work.