Filtration for Printer  

RE: Filtration for Printer

In my humble opinion, you'd be wasting your time and money to simply put this next to your printer.  If you are serious about trapping particulates and odors, you'd have to enclose the machine, and use this filter in a duct so that the inside of the enclosure is at negative pressure while the filter pulls air from the enclosure, cleans it, and vents it into the room.  (At one time, I was on the Safety Committee for a lab that had chemical fume hoods, and you'd be surprised how rigorous the standards are there for capturing fumes.)

If you have never used a 3D printer, you will find that different materials have radically different "emission" profiles.  To me, PETG is odorless and "smokeless"; printing with nylon emits fine particulates (but large enough to be visible, thus easily large enough to be captured by a HEPA filter); ABS really stinks terribly in my nose so I refuse to use it (I don't have an enclosure).  I don't think PLA has very much smell or particulate emissions, but I barely ever use it.  YMMV.

RE: Filtration for Printer

Research into particulate emissions from 3D printers shows that the major factor is whether filaments have been dried prior to printing. Particularly with nylon that's an important step. With dry filaments, the particulate emissions were insignificant.

@retireejay is right that you need an enclosure for the printer if you want the filtration system to be properly effective. Also, HEPA filters will be enough for the particulates, the active carbon is for monomer emissions like styrene from ABS.

RE: Filtration for Printer

According to this webcite and others there are UFP emissions that are too small for HEPA filters (for all filaments)

https://blog.gotopac.com/2018/10/09/carbon-hepa-filters-for-toxic-3d-printing-fumes-particles-odors/

RE: Filtration for Printer

Posted by: Vojtěch

[...] Also, HEPA filters will be enough for the particulates, the active carbon is for monomer emissions like styrene from ABS.

Do you mean HEPA will not be enough? My understanding is that HEPA filters can trap particulate matter down to PM3 and the fine particulates generated by 3D printing are PM2.5 and smaller.

RE: Filtration for Printer

Posted by: bobstro

 

Do you mean HEPA will not be enough? My understanding is that HEPA filters can trap particulate matter down to PM3 and the fine particulates generated by 3D printing are PM2.5 and smaller.

HEPA filters are specified for particles above 0.3 μm (not PM3, but PM0.3) and there they have a very good (99.95% and better) efficiency. The majority of 3D printer emissions by mass are in the 0.2-0.5 μm range, where HEPA filters are efficient and so will arrest most of the emissions. There are still ultrafine particulates (0.1 μm and less) to consider and even there HEPA filters have a reasonable efficiency of around 60%. It may not be enough for a negative pressure system that vents straight into the room, but should be fine for a recirculating system in an enclosure where the air is pushed through a filter continuously while printing, so that there is only a small amount of particles emitted at the end of the print when the enclosure is opened.

But then, it's a question whether it makes sense to worry about the ultrafines, given that people don't put eg. laser printers into enclosures either and in many offices those are running almost continuously.

RE: Filtration for Printer

Posted by: Vojtěch

[...] (not PM3, but PM0.3)

You kill me dude. Tell these guys. 

RE: Filtration for Printer

Posted by: bobstro

Posted by: Vojtěch

[...] (not PM3, but PM0.3)

You kill me dude. Tell these guys. 

I read the whole thing, where does it disagree? It doesn't seem to define the HEPA filter.

RE: Filtration for Printer

Posted by: Vojtěch

I read the whole thing, where does it disagree? It doesn't seem to define the HEPA filter.

The nomenclature is PMxx not PM0.xx. You have this maddening way of correcting things that are not wrong. If PM2.5 is clear, PM3.0 shouldn't confuse anybody.

RE: Filtration for Printer

Posted by: bobstro

 

The nomenclature is PMxx not PM0.xx. You have this maddening way of correcting things that are not wrong. If PM2.5 is clear, PM3.0 shouldn't confuse anybody.

PM10 means 10μm particles. PM2.5 means 2.5μm particles. I would expect that PM3 means 3μm size particles. HEPA filters are effective down to 0.3μm particles. I do not care how exactly that's written, but it's 10 times smaller, so HEPA will have no trouble with PM2.5. That's what I was trying to point out.

RE: Filtration for Printer

Posted by: Vojtěch

PM10 means 10μm particles. PM2.5 means 2.5μm particles. I would expect that PM3 means 3μm size particles. HEPA filters are effective down to 0.3μm particles. I do not care how exactly that's written, but it's 10 times smaller, so HEPA will have no trouble with PM2.5. That's what I was trying to point out.

Gotcha. There is a lot of contradictory information out there, and it would sure help if they'd use consistent language between discussions on HEPA and Ultra-Fine Particles (UFP). So while HEPA is plenty for the larger stuff, it's not going to help with UFPs, which are the concern with 3D printing, correct? My impression, from reading up on the topic, is that typical home filtration is not going to do anything to help with UFPs, which are the health concern. They may help with odd smells and other pollution though.

RE: Filtration for Printer

Posted by: bobstro

Gotcha. There is a lot of contradictory information out there, and it would sure help if they'd use consistent language between discussions on HEPA and Ultra-Fine Particles (UFP). So while HEPA is plenty for the larger stuff, it's not going to help with UFPs, which are the concern with 3D printing, correct? My impression, from reading up on the topic, is that typical home filtration is not going to do anything to help with UFPs, which are the health concern. They may help with odd smells and other pollution though.

Yes, that's right.

A common home airconditioning system will only use G4 filters, which work on particles above 10μm. Even the anti-allergy F7 pollen filters will work on particles above 1μm. A home air purifier with a HEPA filter will work down to 0.3μm. Below that, the efficiency will drop. To be able to handle all UFPs (<0.1μm), H class or E class filters would be needed, but these are not commonly used outside of clean room laboratories, like silicon wafer production. A common household air purifier sitting next to a 3D printer isn't a particularly good way to handle the 3D printer emissions.

And here I go off the deep end again:

UFPs, Ultrafine particles are the new scare, because they're small enough not to be taken care of by the ciliary epithelium of the human respiratory tract and will be transported all the way to the alveoli where they can enter the bloodstream. And nobody knows what they can do there. They can and do carry all kinds of immune reaction-inducing or carcinogenic molecules on their surface. It is assumed they're responsible for large numbers of deaths worldwide annually.

3D printers have been shown to produce particles of all sizes, including the UFPs. By mass the UFPs are a minority, by count, because they're small, they are a majority. Still, the amount produced is tiny compared to eg. diesel engines or even standard laser printers or copy machines. A 3D printer will be a significant source of UFPs in an otherwise empty room, but may become quite insignificant when other common sources of UFPs are factored in.

In the end, it may not be worth the effort to fight the printer emissions if the house has a reasonable amount of ventilation (air exchange with the outside). That's why Prusa and others can sell open frame filters without violating any health codes.

A fairly common setup, mainly for printing ABS, because it smells, is an enclosure with a recirculating air scrubber. A fan in the enclosure pushes the air through a HEPA filter, a carbon filter and then the air goes back into the enclosure. Again and again and again, passing the air through the filter constantly. This way, the HEPA filter will easily take care of the coarse particles (10μm-2.5μm) and even fine particles (<2.5μm) with 99.95% efficiecy guaranteed on a single pass. It will struggle with the UFPs (<0.1μm), where the efficiency is reported to be in the 60% range. Still, if you cycle your air 10 times through a 60% efficient filter, you get 99.98% efficiency.  The activated carbon will then take care of the VOCs (volatile organic compounds), the smelly molecules. So even if you're after being super-safe, such a setup should be enough.

RE: Filtration for Printer

.... open frame printers without ...

RE: Filtration for Printer

Voj - expert in all things... lmao.

PMx.x infers a range of particle sizes being counted. And there is no absolute limit nor efficiency number that encompasses what is and isn't removed in all cases by any specific filter.  To make that sort of statement is, well, silly.

RE: Filtration for Printer

As for the OP, there are two things filters try to eliminate from the air (and I use filter loosely): particles and gasses.  Particles being the dust we breathe, gasses being the farts we smell.  HEPA filters are designed to remove dust like particles. They do nothing for gasses (or many VOC's), and that's why people use carbon and other organic absorbing products to remove odorous gasses along with the HEPA filter that removes the particulates. 

And yes, I am using the term gasses a bit loosely, but it's okay because the subject is home printing, not class 1 clean room air cleaning in microTorr diffusion vacuum pump assembly plants.

RE: Filtration for Printer

Posted by: Tim

Voj - expert in all things... lmao.

PMx.x infers a range of particle sizes being counted. And there is no absolute limit nor efficiency number that encompasses what is and isn't removed in all cases by any specific filter.  To make that sort of statement is, well, silly.

I think Voj was pointing out that HEPA is 0.3, just in a manner that made it sound like the nomenclature I was using was incorrect. I was off on the effectiveness of HEPA, so my HEPA value of PM3.0 was off, so mea culpa on that one. I do wonder why the hell they don't align the HEPA and particulate pollution jargon to avoid the confusion. In any case, even HEPA is insufficient for ultra-fine particles, which is the point *I* was trying to make (and that you're expressing better). At least my HEPA filter is clearing out some of the pollen we're experiencing this week.

RE: Filtration for Printer

Posted by: Tim

Voj - expert in all things... lmao.

Nah. Ask me about literature, pop culture, arts, and you'll get a blank stare from me. 🙂

PMx.x infers a range of particle sizes being counted. And there is no absolute limit nor efficiency number that encompasses what is and isn't removed in all cases by any specific filter.  To make that sort of statement is, well, silly.

There are specifications of filter classes and accompanying tests the filters must pass to meet the specification.

Prague used to have a very serious pollution problem when I was growing up. It was mainly brown coal used for heating and industries that was the reason. I developed asthma and some allergies back then. Even a couple of years back the air pollution was way in the unhealthy range every winter. And so half of my attic is filled with massive filters and fans and cylinders of activated carbon, a heat recovery unit, a heat pump, an UV-C sterilizing lamp, a 300W ultrasonic humidifier, all controlled with an array of sensors to make sure the air in the house is reasonably clean. So yeah, I've been a bit into filters.

RE: Filtration for Printer

Sorry - I'm calling it bogus. Don't know which Google site you're copying data from, but it isn't in your noggin. 

RE: Filtration for Printer

I'm looking into this issue currently. As stated in another thread, I'm having problems with my ambient temperature in the garage and printing with PLA. The reason I put the printer in the garage is because I can run all night without noise problems, and more importantly my family isn't in there constantly to inhale the ultra-fine particles.

I have a great spot I could use in my indoor office, but the door is normally closed and no easy window access so the ventilation is poor. I'm in this room 12+ hours a day. I haven't looked seriously into filtration because as I understand it, it's very difficult to do properly. I'd rather not build an air-tight enclosure around the printer.

Am I being paranoid in wanting to avoid printing PLA in my home office, or is this a common setup?

Printers in residential spaces seems to be a relatively new situation and as such not a lot of studies to back up opinions. Today I talked with a guy at my plastic supplier and he said I "should be fine" printing with PLA indoors, as that is what many schools they supply use. Yet those kids aren't sitting 5 feet away from the printer for 12+ hours a day, and most school likely move a lot more air than my home. I'm confident the supplier of my plastic (PushPlastic) isn't knowingly putting any dangerous coloring agents into their PLA, but the ultra-fine particles make me uneasy.

RE: Filtration for Printer

PLA is made from essentially plants and long term studies have found it to be compatible with human and mammal biology (do a Google search).  That is, the stuff given off when printing PLA is generally accepted as safe around humans.  On the other hand, ABS byproducts are known to be toxic to mammals.  

If your plans are mostly PLA, then indoors is fine.  If your plans include a lot of ABS and exotics (nylons, carbon fibers, polys), print outdoors so your neighbors get the smells and problems, or invest in a good enclosure with a charcoal based recirculator and heat exchanger.  I haven't done any of these, but based on what I've read, the cheapest way it DIY; but requires a bit of engineering know-how.