Filtration System

Does the community think a filtration system is needed for 3D printers. The following questions are asked in order to get the communities opinions.

Do the fumes and by products from PLA and ABS pose health hazard? (Yes or No)
Would you buy a filter if you knew it was recommended for safety/health? (Yes or No)
How much would you spend on a 3D filter?
Why wouldn't you buy a 3D filter?
Why did you purchase a 3D printer?
How much is your 3D printer worth? 
What is your age?
What state/country do you reside in?

Any information is appreciated for our school's project.
~ Nick

Schools project or Kickstarter project?

Are you a teacher?

This is for a school project. I am a student.

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FouthDimensions
Do the fumes and by products from PLA and ABS pose health hazard? (Yes or No)

There has been a study done (built-envi.com) that shows that concern over ultra-fine particles emitted by 3D printers warrants an enclosure, so yes. I would add that fire detection / prevention should be a feature of the enclosure.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

Dave,

Would you buy a filter for your 3D printer, if you have one?

3D Karma,

Are you a vendor? If so, would you be a proponent of a filtration solution and add it to your product line?

Seems like a good drop-in (or drop-over) hood-with-hepa-filter-and-fire-alarm might be a good kickstarter.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

Fouthdimensions:

I have about 18 months 3d printing experience now. If you had asked me a year ago I would have said no, but now I know a bit more about the hazards I am planning on some sort of extraction or filtration.

3dkarma:

People getting ideas from others on here then starting a Kickstarter project does not sit well with me. It would certainly make me more reluctant to make suggestions.

Currently this is a school project for our business class. This would be a great kick starter project, but that is not the intent at this time. The idea we have is an enclosure. The fire alarm is a great idea that we did not consider. Would you consider a product like this to add to your product line? How much would you as a vendor like to price it to your customers? We are compiling the material and labor costs currently. Your input is valuable.

FourthDimensions
~Nick

Dave3D this is not a kick-starter project. I would like your input on what pricing point as a consumer you would pay for a filtration system would be. This gives us one more metric to add to our slide deck for our professor.

Not sure which country you are living, but I am in the UK.
A simple replaceable carbon filter in a purpose made plastic housing with a mains powered extraction fan?
Needs to be less than 100 euros I think. With a built in alarm ........... maybe 150 euros max.
Building it with a large hood that covers the entire printer, quite a bit more. Who knows?

I am currently working on a filtration system!

Be advised - we are talking about particle sizes of about 8 - 90nm!!

These are so small they can and will pass blood-brain-passage (how do you say it in english? i am not a native speaker)
They will enter cavaties of your head, of your lungs - going to the finest alveols and (maybe) stay there?!

bio-degradable is a very stretchable term!
what happens at 50°C under special circumstances does not need to happen in your body...

plus some PLAs have extremly! hazardous additives - like Bisphenol a and sevral other substances even more dangerous substances -
I once purchased PLA from Velleman - it stank so bad and got me a bad headache.
For information puprose i looked up a saftey datashet - it said do not touch or expose to skin...
there are substances in there which have been forbidden in childrens toys and plastics which are used in households in general for the last 11 years, yet it is "ok" to heat em up in your living room...

I see, not letting children touch it for prolonged periods of time ok... but then melt it/heat it up to about 210° apply pressure and extrude plastic in your living room?!
great...

You gotta think around the edge here!

You have to use filters which are commonly used in plastic extrusion industries.

Look up on the web, what kind of safety regulations there are for plasic extruion and talk to some companies that do plastic extrusion - they have high safety regulations, any workers involved in processes must wear high-level respiratory devices and filters and they have huge and expensive filtration systems.

What will happen to cheap filters?!

An oily slime will built up on them really fast and blocking the fine pores.

Filtration needs to be done in different stages
and You should use high-end filters!

there is a difference between using a 3mm cardboard-like piece of carbon-filter
or some 2-3 cylindrical Filter "cans" Full of active carbon - about 3-4 kilos. with several other specifically deigned up to the task filters in front of it.

Imagine - 3mm filament squeezing out of a 0.5mm nozzle (which is rather big these days) produces around 150bars of pressure inside the nozzle!
going down to 0.35 will up this only more

This means that together with the rather high Temperatur of 190-220° or even more for Acry-Nitril-Butadienstyrol - ABS
you WILL Crack the plastic molecules and produce unknown ne molecules - being emitted in the amount of millions and billions - creating extremly big surfaces to react (remember, the samller particles get, the bigger there surface becomse compared to theri volume)
so they tend to be/get very reactive and more then like irritating and even carcinogen.
Cracking plastic molecules on your workdesk - while sitting in front of it and hanging with the nose a few inches away while watching your part grow...pretty dagerous - unfortunately nobody knows/seems to care?!

How much are you willing to pay for "health"?! that is the real question which should be asked.

For most purposes the easiest way would be to lead the particles somewhere else - like outside.

About that being ethical ?! i dunno...

The more sphisticated way of doing it, is via a complex filtration system.

You will understand, that I will not give away the exact Filters and devices used - as I don`t wanna hurt my own business interest,
but I can safeky say - ask around in the plastic-Extzrusion industry- they know their stuff!

and - a 3D printer at home is nothing short of a small plastic extrusion machine - including all the health hazards of a big one, yet people are letting these fume and particle flooders sit on their desks, livingrooms and even sit in front of them hour after hours, watching it print and deeply breathing in thos hazardous particles...

scary sh*t if you ask me ;-)

Alex

Edited 1 time(s). Last edit at 11/10/2014 05:01PM by Alexander1984.

Dave3D,

That sounds about what we are projecting. We are in the US. Do you mind informing us what 3D printer you have or have had?

FourthDimensions
~Nick

Alex,

Looks like you have been doing quite a bit of research. Where are you located? I agree with the points you make on how much is your safety worth. It is scary on what can be the long term health issues.

I have got an OrdBot Hadron, which I ordered from the US as kit. I have since modified it quite a bit.

Is there any way you can provide the dimensions and a picture for the modified OrdBot Hadron?

Here is an older photo. It is in bits at the moment while I do some more mods.
Bed size is standard reprap 200 x 200.

Dave3D,

The prototype we drew was a 2' x 2' x 2'. We are thinking a pricing point would be 180 - 200 USD. We have about three to four weeks left on this project.

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Alexander1984

Imagine - 3mm filament squeezing out of a 0.5mm nozzle (which is rather big these days) produces around 150bars of pressure inside the nozzle!
going down to 0.35 will up this only more

While I agree more or less with the concern of having a 3d printer near children... can you please tell me how you can prove that the pressure inside nozzle is 150 Bars (= 150 Kg/sq.cm ).

Best Regards
Davide Ardizzoia*



* currently selling enclosed printers with printing fumes duct :-)

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no toys here...sorry

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3ntrlab

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Alexander1984

Imagine - 3mm filament squeezing out of a 0.5mm nozzle (which is rather big these days) produces around 150bars of pressure inside the nozzle!
going down to 0.35 will up this only more

While I agree more or less with the concern of having a 3d printer near children... can you please tell me how you can prove that the pressure inside nozzle is 150 Bars (= 150 Kg/sq.cm ).

Typical 1.75mm extruders push with 10-20N of force. That is distributed over 2.4sqmm, or 0.024sqcm.

15/.024 = 62.5 bar.

Of course 15N is just a general average based on Airtripper's measurements, so 150 bar is not out of the question.

Edited 1 time(s). Last edit at 11/24/2014 09:00PM by greenman100.

My responses:
Do the fumes and by products from PLA and ABS pose health hazard? (Yes or No) Yes.
Would you buy a filter if you knew it was recommended for safety/health? (Yes or No) Yes
How much would you spend on a 3D filter? $150 or less
Why wouldn't you buy a 3D filter? If it was too loud, to expensive, or didn't fit my setup.
Why did you purchase a 3D printer? (made one) to make machine prototypes
How much is your 3D printer worth? > $4000
What is your age? 52
What state/country do you reside in? USA

OK, now I'm a bit ticked - this is way too important to be proprietary! This is a great place to come together for an open source solution, so let's get to it, shall we! In a few minutes I found the following.

If the printer is enclosed then a high CFM is not going to be required, therefore more inexpensive components can be used than in industrial filters. Since we are reprappers, we can make our own housings as needed.

Here is a link to a fan and carbon filter combination:
Carbon Filters

Here is a Carbon Filter that's interesting all by itself.

This could be used as a pre-filter: HEPA filter good for .3 microns

And here is another with larger capacity

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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 was looking at a bilge fan [www.amazon.com] in line with a dyson HEPA filter [www.amazon.com]. Low cost and it should be straightforward to print a housing to get the two to mate and mount to an enclosure. Hook up a speed controller to the fan and you can manage the inevitable draft. Please note I'm not the originator of this idea - I read it elsewhere in the forums.

My problem is that a HEPA filter is good for 0.3 micrometers, or 300 nanometers ([en.wikipedia.org]) while there seem to be issues with UFPs that need to be addressed ([3dprintingindustry.com]). There are HECA filters being developed at the moment that will capture better than 90% of UFPs, but these are targeted at the automotive industry and aren't yet generally available (so far as I'm aware - please jump in if you know better).

Regardless, a good start has to be a HEPA filter.

Edit: carbon filters are good for particles from 500 to 50K nanometers ([en.wikipedia.org]). UFPs are less than 100 nanometers ([en.wikipedia.org]).

It looks like a filter with a MERV 16 rating would help significantly, according to this study: [www.ncbi.nlm.nih.gov]. According to this blog post [pureairsystems.wordpress.com], HEPA filters are roughly equivalent to a MERV 18 (if the rating went that far), so it sounds like the best way to start is with a HEPA filter.

Edited 1 time(s). Last edit at 11/25/2014 03:19AM by 3dkarma.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

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greenman100

Typical 1.75mm extruders push with 10-20N of force. That is distributed over 2.4sqmm, or 0.024sqcm.

15/.024 = 62.5 bar.

Of course 15N is just a general average based on Airtripper's measurements, so 150 bar is not out of the question.

Pressure is applied all around in the melting chamber, not only as a frontal section....average 3mm nozzles are about 120-150 sq.mm. (ten times more....).

Brgds,
Davide Ardizzoia

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==============================
no toys here...sorry

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3ntrlab

Quote
greenman100

Typical 1.75mm extruders push with 10-20N of force. That is distributed over 2.4sqmm, or 0.024sqcm.

15/.024 = 62.5 bar.

Of course 15N is just a general average based on Airtripper's measurements, so 150 bar is not out of the question.

Pressure is applied all around in the melting chamber, not only as a frontal section....average 3mm nozzles are about 120-150 sq.mm. (ten times more....).

Brgds,
Davide Ardizzoia

I'm sorry, but you are incorrect. Changing the size of the chamber does not change the pressure - if it did, hydraulic systems would not work.

Pressure = force/area. The "area" is the crossectional area of the piston (hydraulics) or filament (3d printing) that is being pushed with F (force).

Edited 1 time(s). Last edit at 11/25/2014 11:50AM by greenman100.

Good info 3dcarma.
So we are looking at filtering particles that are 100 nanometers or less. This is .1 microns or less.
Some ULP filters are rated at 99.999% of particles 1.2 microns and less. These are used in vacuums used to clean up toner and other hazardous materials.

I think this would be OK, provided the airflow is sufficient at the minimal rate needed for an enclosed printer. What do you think? And a pre-filter?

This was an interesting article.

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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!

@Paul,

It seems that neither ULPA nor HEPA are going to crack the problem, as they're both rated for particles larger than 0.1 microns (0.12 or larger for ULPA) source: [www.sentryair.com].

If we can't find a filter for 0.1 microns and smaller at a reasonable price point, the question then becomes one of how efficient are readily available ULPA / HEPA filters at filtering 0.1 microns and smaller. They have specific ratings for a given particulate size and up, but what percentage of smaller particles will they filter, and is that sufficient for our needs?

According to this study [portfolio.syracusecoe.org], an HEPA with activated carbon prefilter approached 0.6 or 60% effeciency of filtering UFPs under conditions simulating a room in the home. an HEPA panel filter (without prefilter) was somewhere between 40% and 50%, if I'm reading the results correctly.

Is that good enough? Chances are a ULPA filter with an activated carbon prefilter will perform better, but I can't find anything that states it definitively.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

3dkarma,
That's an interesting study from syracusecoe.org. They are testing a different scenario from what I envision: they are filtering an entire room. Because of this a high particle separation efficiency will lower the performance they were testing for - since there is lower airflow with a very fine filter it can take longer to clear the room.

I think we need to define some assumptions. These are mine which will not fit all situations or tastes Feel free to disagree.

1- To capture as many of the particles as possible the printer should be enclosed. Otherwise breezes will carry the particles into the entire space, and into any a/c system.
2- Since we are capturing air directly from the enclosure we can achieve near the theoretical filter efficiency.
3- Adding filter depth with an additional pre-filter will increase the amount filtered and prolong the life of the ULPA filter.
4- There should be minimal airflow through the filter - enough to create a slight negative pressure in the chamber, otherwise the chamber will be cooled. This flow amount will vary depending on how tight the enclosure is.
5- Filter efficiency increases with decreased airflow - a perfect scenario for an enclosed printer.
6- The filter efficiency rating should be approximately EU15
7- A filter that filters 99.999% at .12 microns will have only a slightly lower efficiency at .08 microns. See Here.

What do you think?

@Paul,

I agree with you on the likely improved efficiency of a filter attached to an enclosure. Unfortunately there's not a lot of available studies that fit the scenario we have - this was one of the first relevant studies I found. Regarding your assumptions:

1. Granted.
2. I have neither evidence nor experience to back this up. Are you aware of anything that supports this assumption?
3. The study I linked to seems to support this. The improvement gained from adding an activated carbon pre-filter seems sufficient enough to warrant adding one.
4. A definite requirement for ABS printing, given the experiences related in this forum. Printing in PLA may require a higher rate of airflow to allow for cooling, though, as PLA likes being cooled as it's printed.
5. Don't know either way.
6. According to the link, EU14 (HEPA) would approach 98% (guesstimate - the scale is logarithmic) at .01 micrometers. EU15 (ULPA) doesn't appear on the chart, although it is reasonable to assume higher efficiency. Check this link for more information on MERV / EU ratings [www.afprofilters.com]. Are we happy with 98%, or should we shoot for 99% or better?

Some basic requirements we need to consider:
A. The filter should be affordable.
B. The filter should be of a reasonable size (to be defined).
C. The filter should last for a reasonable amount of time (several hundred printing hours).
D. It should be simple to change the filter, with little waste.
E. The filter should be readily available.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

3dkarma,

On point 2, it is my assumption only - as I am assuming that 100% of the particles are being captured at the source due to the enclosed chamber, and all of that stream is going through the filter. If the printer is a more open design and not enough CFM to capture, then there will be leakage.

On point 4, I agree when printing PLA more airflow may be wanted, or it can be directed to the printing area by placement of the opening (additional fan then not required).

On point 5, I have read many places that lower flow velocities improve filtration efficiency.

Quote

The next filtration mechanism, diffusion, is effective for very small particles typically less than 0.5 μm in size. Effectiveness increases with lower flow velocities. Small particles interact with nearby particles and gas molecules. Especially in turbulent flow, the path of small particles fluctuates randomly about the main stream flow. As these particles diffuse in the flow stream, they collide with the fiber and are captured. The smaller a particle and the lower the flow rate through the filter media leads to a higher probability that the particle will be captured.

Note that ULPA filters do not filter gasses, so the carbon pre-filter will be wanted for that.

On point 6, for myself I would prefer 99+% at .1 micron.
It will cost probably $25 more for 99+% than 98%. I think 99.9+% is achievable for under $150 now, which is virtual elimination of the hazard.

I agree with all of your excellent points. I would add one in addition: The filter system should be tolerably quiet.

Finding the appropriate items is always the most difficult part. The ones I have found so far are not compact.

There are 5 main components, and these will vary by implementation:
1 - The Fan, perhaps like this one that has good static pressure
2 - The carbon pre-filter
3 - The main filter
4 - The ducting/enclosure
5 - The electronics (Power supply, power switch, fuse, speed controller)

Anything I'm forgetting?

Edited 1 time(s). Last edit at 11/25/2014 06:00PM by Paul Wanamaker.

Good point about the noise volume.

I guess I'm pushing more for HEPA due to availability here in the UK. If I could find an affordable ULPA filter that was a reasonable size I'd jump at it.

I like the fan, although I'd personally prefer 12V as that's what most of us use for power supplies. I'm quite fond of the idea of using an in-line bilge fan.

I think you've covered the bases regarding the parts list (fixings notwithstanding). On another note, it may be of use to circulate the air back into the enclosure when printing ABS, to help with temperature control.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.