Filtration System

Are we over-designing this? Why don't we slap together some MDF, stick a grow room extractor fan / carbon filter in a hole, duct tape a ULPA / HEPA filter in line and call the job a good 'un?

---

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

Excellent. Recirculating will increase the capture. I have to balance that with the need to be able to dump some heat tho.

I think we've covered the bases.

I'll do some more searching to see if I can find a smaller and cheaper ULPA filter that the one I found above, a smaller carbon filter, and a quieter blower, perhaps 12v.
I like blowers as they typically have a better static pressure curve at lower RPM.

Regards
-Paul

---

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!

Re "Are we over-designing this"
Now that we understand the issue, sure MDF and duct tape would work fine. Go for it.

I have to design something that will work with my printer, as it is already tall, and has to fit through the door.

Edit: I found the following more compact ULPA filter ORK-ULPACAS-09 for $16.25 plus shipping. More expensive other places. It looks like vacuum exhaust filters are a good category for these UPLA filters. This one also available in other countries here. I don't know what it's size is. Google search

Edit:
So before I design something I'm doing some investigating of whats already been done.
Here's a filter setup using a bilge fan and filter Thingiverse
Here is one that uses a respirator filter Thingiverse and another related
This one uses two fans and just carbon.

So I've completed my search of what's been done. OK, but not what I'm looking for.
I will design something that has better air flow, uses inexpensive activated carbon and the ULPA filter I found. I'd like to get the cost under the $75 that I'm at now (mostly because of the fan).

Edit:
I think a blower type fan is needed since a typical axial fan can only deliver a low static pressure (unless it's very loud).
I found four 12v blower fans with static pressure between 1.64 and 5.4 In/H20 that range in price from $20.79 to $27. I don't know yet how much pressure is needed. I may get the one with 3 In/H20 static pressure as I can always turn it down (rpm is usually the only difference with these fans). 61 DB would be pretty loud otherwise. It will be muffled somewhat by the filters too. This brings the price down in the $50 range.

Here they are:
56 DBA 36.8, 1.64 IN/H2O, $20.79
57 DBA, 39 CFM, 1.97 IN/H20, $24.89
61 dba, 47.3 CFM, 3 IN/H2O, $23.80
66 DBA, 56 CFM, 5.4 IN/H20, $27.00

Edited 10 time(s). Last edit at 11/26/2014 04:50PM by Paul Wanamaker.

Paul,

I would be honored if you took a look at our design that we have created for a project in our business class. Would you be open to the idea. Our price point currently is at 118 with a ULPA filter. We have an enclosure to trap all the BPAs.

~Nick
Fourth Dimensions

Well done on finding a ULPA filter at that price point. The only filters I'm able to find in the UK (or readily available in Europe) are specialist products and significantly more expensive. The cheapest was $72.

---

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

Nick - I would be very happy to take a look at it. Are you planning to build a prototype? Would you mind publishing a link to it here after you've completed your project? I think this is a critical issue and really want all the info out.

Having watched some of the videos of what has been created for existing printers - I now see the need for setup with a higher volume airflow to retrofit them, especially if they need to use a hood. I hope that in future all printers will have a filter.

3dkarma - thanks! I was thinking that you might be able to find a ULPA respirator filter that would work, but the static pressure of the fan/blower that's used may be even more critical if those filters are more restrictive. I've read about ULPA respirator filters, but I haven't searched for them.

My next step is to order a blower and ULPA filter tomorrow.
- I have designed a carbon filter that can be 3D printed and will use about $5.00 of activated carbon. I'm hoping it will have low air resistance. I need to find a filter material to contain the activated carbon. I may just purchase a furnace filter and use that as raw material. Need to do more research...
- I need to measure the actual ULPA filter and blower before I finish the design as they will be integrated.
- Some people use oil to lubricate the filament (I do) so I'm considering a pre-filter before the carbon filter to absorb any oil residue in the stream - it could be just cotton batting perhaps.

I've ordered the filter from www.vacuum-direct.com for $27.80 with shipping,
Ordered the 9BMB12P2K01 blower from Newark.com for $37.16 all in. The other models were out of stock where I looked. It's quite a bit louder, but I have the option to turn it way down...
I ordered some granular activated carbon from Amazon for about $6.00.
I will need a bit of filter media to contain the activated carbon. I'll see what I have around.

So everything is ordered. When it all comes in next week I can measure the items, finalize the design, and get printing.

---

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 received both the ULPA filter and the blower fan.

The filter comes in two shapes: cylindrical or rectangular, both cost about the same amount. I could not find the sizes, so I chose the cylindrical filter.
It's a bit larger than I expected, I'll bet you can get quite a bit of air through it. Photos attached.
Note that you need to use a pre-filter with these very fine filters.

The dimensions of the ULPA filter are:
Diameter: 200mm or 7.87 inch
Height: 100mm or 3.93 inches.

I have a bit of head-scratching to do to re-design this now that I have the pieces - as I mentioned the filter is bigger than expected!

It would be great if someone could find out the dimensions of the rectangular filter, I'm not planning on getting it however as I will use what I have now.

---

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, given you have a heated chamber and are using electrical energy to heat the chamber are you recirculating the srubbed chamber air so the heat is not lost? This would ensure the temp inside the chamber did not fluctuate during printing. This being said the door and sides would have to be sealed as a negative pressure would not be created in the chamber unless a small portion of air is always exhausted to the atmosphere. If using a recirc system an atmospheric bypass valve that clears the air from the build chamber and expells it outside when printing is finished could be added so the air is clean before opening the door to remove the part. This however would only be needed if the filters did not remove all the odours and particulates.

just a few thoughts and thanks for sharing

---

My delta build blogspot [d3delta3d.blogspot.com.au]

Custom Delta printer
300x500 build volume
magnetic effector
Smoothieboard controlled

d3delta3d,
Yes I will be recirculating the air.
I initially thought I would have extra heat and would need to dump some, but now that my heated bed is being accurately controlled I do not have extra.

Good ideas, thanks. I am thinking about venting a small amount of scrubbed air so there will be lower pressure inside. This will of course vary greatly by printer design.

I've been working on the filter design. Added a HEPA filter between the carbon filter and the ULPA filter, as the ULPA filter must have pre-filtered air or it will plug much faster. I got a HEPA filter that will luckily nest with the ULPA filter. None of these have dimensions on the web...

So the filter sequence is Carbon filter, HEPA filter with it's own foam pre-filter, and the final ULPA filter. Both the HEPA filter and the ULPA filter have large surface area, and I think they will not restrict airflow too much for this application. Testing will tell..

I'm designing the carbon filter at this point, I'd like to make it more compact, and I'm joining things together. I'm trying to make them as easily printable as possible, so there will be lots of changes in the next week.

love this thread
so your saying if i enclose my 3d printer. and with a simple hepa filter [www.amazon.com] with a pc fan [www.quietpc.com] 3d printed encloser and 12 volt speed contorler [www.banggood.com] will reduce emitions by 98% im up for that

are am i missing a step ??

Edited 3 time(s). Last edit at 01/02/2015 05:49PM by aparkin.

Aparkin,
Hepa filters remove 99.97% of particles that have a size of 0.3 micron and larger.
That alone is may not be enough as many the particles we are worried about here are about .1 micron.

A ULPA filter however will filter 99.999+% at .1 micron. That's more like it.

The trick is that you need to filter in stages so the ULPA filter does not immediately get plugged up.

I am finalizing a design that uses filters that I have found and linked above. I hope others may find more compact filters...

In the image, on the left side is the blower, that blows air into the carbon filter.
On the right side is an assembly of the nested HEPA filter (which has a foam pre-filter) and ULPA filter with an outer enclosure duct that returns the air to the chamber.

This is a starting point..
Still to do: refine the connection between the components, and make it more compact. There will be a fared duct between the blower and the carbon filter chamber.
I have all the parts.
When I have completed the design I will build a prototype. My Smoothieboard will be here soon so I can print again...

Edit: Since I posted this I've figured a way to nest all the filters so it will be one unit. I'll post that up when it's ready.

Edited 2 time(s). Last edit at 01/02/2015 10:35PM by Paul Wanamaker.

---

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 completed the first complete rough draft of the Reprap Filtration System, v0.1

I was able to make this one unit that's fairly compact. If you can find a more compact ULPA filter then this could be made even more compact.

I am attaching a view of to top, bottom, and an exploded view.

Starting from the bottom you have:
The fan,
The Bottom Duct,
The Carbon Filter Tray,
The HEPA filter with foam prefilter (black and blue),
The HEPA filter Shroud (pink)
The ULPA filter (light blue)
and the Outer Duct with return duct.

I will need to make packet of activated carbon that would sit in the Carbon Filter Tray. This might need something like screen above to fasten it in place.

Note that the Outer Duct can swivel (before it's screwed in place) to change the spacing between the inlet and outlet.

The way it would be assembled is this:
The Carbon Filter tray sits on the Bottom Duct (with a gasket)
A Carbon Filter packet will sit inside that.
The HEPA filter will be attached to the HEPA filter Shroud with a few screws, and that assembly would sit on top of the Carbon Filter Tray.
The ULPA filter will sit on top of that. It has a rubber gasket already.
The Outer duct will sit on top of it all, and will put some pressure on the ULPA filter to seal it.
There will be screws around the base of the outer duct which go down through holes in the HEPA Filter Shroud and the Carbon Filter Tray, and screw into the Bottom Duct sealing the entire assembly. There may be gaskets between the layers... I can laser cut some material I have for that.
There will also be screw holes in the output duct to seal that to the enclosure also.

Next:
Place screw holes in the model.
Put some mounting tabs on the Bottom Duct.
Determine the makeup of the carbon filter packet.
Design a small spacer for under the fan.
Check print-ability of the four printed parts.
Determine if I need to allow for venting some filtered air, and if so - how much.

---

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 completed the first complete rough draft of the Reprap Filtration System, v0.1

I was able to make this one unit that's fairly compact. If you can find a more compact ULPA filter then this could be made even more compact.

I am attaching a view of to top, bottom, and an exploded view.

Starting from the bottom you have:
The fan,
The Bottom Duct,
The Carbon Filter Tray,
The HEPA filter with foam prefilter (black and blue),
The HEPA filter Shroud (pink)
The ULPA filter (light blue)
and the Outer Duct with return duct.

I will need to make packet of activated carbon that would sit in the Carbon Filter Tray. This might need something like screen above to fasten it in place.

Note that the Outer Duct can swivel (before it's screwed in place) to change the spacing between the inlet and outlet.

The way it would be assembled is this:
The Carbon Filter tray sits on the Bottom Duct (with a gasket)
A Carbon Filter packet will sit inside that.
The HEPA filter will be attached to the HEPA filter Shroud with a few screws, and that assembly would sit on top of the Carbon Filter Tray.
The ULPA filter will sit on top of that. It has a rubber gasket already.
The Outer duct will sit on top of it all, and will put some pressure on the ULPA filter to seal it.
There will be screws around the base of the outer duct which go down through holes in the HEPA Filter Shroud and the Carbon Filter Tray, and screw into the Bottom Duct sealing the entire assembly. There may be gaskets between the layers... I can laser cut some material I have for that.
There will also be screw holes in the output duct to seal that to the enclosure also.

Next:
Place screw holes in the model.
Put some mounting tabs on the Bottom Duct.
Determine the makeup of the carbon filter packet.
Design a small spacer for under the fan.
Check print-ability of the four printed parts.
Determine if I need to allow for venting some filtered air, and if so - how much.

Please look it over. I value your comments.

Edited 1 time(s). Last edit at 01/05/2015 03:38AM by Paul Wanamaker.

---

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!

If you're interested in a slightly simpler but slightly less efficient solution, the Scott Safety Promask Replacement Filter P3 to EN 143 has a reasonable performance profile for particulate sizes of 70 nanometers (.07 µm / micrometers) and up. The ULPA standard specifies removal of at least 99.999% of particles 0.1 µm or larger. The Scott P3 filter removes 99.9993% of 0.07 µm, 99.9963% of 0.12 µm, 99.9936% of 0.18µm, 99.9948% of 0.22 µm and 99.9981% of 0.32 µm, according to the following: [www.scottsafety.com] (look for the filtration efficiency slide).

The Scott filter is a safety mask filter and is more available and at a much more reasonable price than ULPA filters in the UK (and possibly other areas). Other companies such as 3M manufacture something similar (e.g. the 3M 2183 P3 R), although it's difficult to find specific performance figures.

Please note that the life of the Scott filter will most likely be shorter than that of an industrial ULPA filter tasked for vacuum cleaners or room filters. While it would be possible to use the Scott filter on its own, the life can most likely be extended by including activated carbon and HEPA pre-filters, as Paul is designing.

---

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

I got a 20x20 box fan and duct taped to it a 20x20x1, .3-micron HEPA filter (the kind you put in your house) from Ace Hardware. Then I plugged all the openings in the printer with clear plastic, stuck the fan behind the printer, and sealed off the space with more clear plastic. It's not perfect, but it eliminates the smell - such that I don't notice it. Maybe a few nanoparticles are getting through, but while you're waiting for a perfect solution, why not invest the $50 and make it a bit safer?

What about using CPAP filters they are cheap, and according to this site they filter out viruses and they can be smaller than 0.1 micron.
[www.cpapfiltersandsupplies.com]

Those CPAP filters are typically about an inch by an inch or so (I have a cpap machine). It might work, but that seems a bit small.

I want to set the record strait in this thread.
After further research I do not believe a ULPA filter is required, as a HEPA filter will actually filter the smaller sizes very well, it's filtering capability does not get worse with smaller particles, it gets better due to a change in the type of mechanism that happens for very small particles.

The rated efficiency 99.98 at .3 micron for a HEPA filter is the particle size where it does the worst job filtering particles, for other particle sizes it does better.

Please see the following thread where HEPA efficiency was discussed, with references and graphs, and some good/inexpensive solutions were found: Charcoal Filter tread. If you disagree after reviewing the information you find there, please correct me (with sources). We do need to get this right.

Here is the best solution I've seen so far, and it is easy to implement: use a respirator filter (rated P100) that has a charcoal filter in it (that has the same rating as a HEPA filter). The STL files and discussion for the air scrubber are found here on Thingiverse.

There is now a kickstarter proposing an adaptable fabric filtration enclosure.
this is here [www.kickstarter.com]
It seems they have done test in controlled environment
There is not much detail about the filters and that raise question about future availability of filters.
This is interesting but does not seem to have a lot of success.
It does have the advantage to add some insulation to the printer which may improve prints.

HI guys, interesting reading. I was going to reference the thread I started about the charcoal filter but it seems you've already found it. I found that (without doing scientific testing) the recirculating system whilst rather cobbled together and prone to coming apart did seem to be capable of removing the volatiles, there was no odour after prolonged ABS printing, and I presume a great deal of the UFP's. I did plan to weigh the HEPA filter to 0.01g accuracy before and then after a long test, but my pre-filter did not work well so I removed it and therefore most of the increased mass would be likely household dust, which is as close to scientific as I managed to get. It is interesting that HEPA filters particles smaller than 0.3 micron but that's the particle size at which it is least efficient.

I was going to move forward to a second prototype (a little more thought-through as proof of concept seems successful) essentially a box with an inlet duct and an outlet duct, these could be attached to an existing enclosed printer wherever is easiest. So an easy add-on. In the box the path for the air flow would first encounter a pre-filter for dust and large particles probably washable foam-type stuff, then HEPA, then carbon either filter pad or granules (very cheap - easy to replace, and easy to fill conical vacuum hepa filters with), then the fan and then as an option a heater based around a hairdryer element. The whole thing would have its own power supply and a controller which could accept an off/on signal from the printer controller and possibly a chamber temperature request signal. The temperature is then controlled either by the printer controller or by this unit independently, a thermistor running from this box to be placed in a reasonable position inside the printer. Ideally the printer controller should control the chamber heater using the second extruder thermistor/mosfet output, as then the heat can be remotely adjusted/turned off, and will shut off at the end of a print, perhaps with a fan run-on timer to allow more filtration time before opening the chamber.As an added layer of safety the original hairdryer thermal cutout could be employed but located so that it would not trigger during normal operation. Inside the hairdryer it was too prone to triggering as the air entering the hairdryer was pre-warmed.

All this being said, I have now bought from ebay a room filter unit which has HEPA/Charcoal and runs at between 20-70W mains. I leave it running on low 24/7 in the room where I print, and turn it up when printing ABS. The room has barely any detectable ABS odour after this thing has been running for a few hours. Not quite as neat as a printer based unit, but cheap, easy, readily available replacement filters and works for open printers, and multiple printers, so it has some merit.

---

Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions