For various reasons I’m trying to build a HEPA/active charcoal filtered enclosure for a large delta printer (1m towers, 350mm diameter bed). Does anyone know what kind of airflow I should be aiming for to keep the air in the chamber relatively odor-free? Obviously the filters will need to be selected to match that flow, but none of the very rare studies outlining the particle emissions manage to really give an idea of how much ventilation is really needed.
Also, has anyone used the Zimpure filters before? Does it work ok, even without an enclosure around it? I can’t really find much feedback on whether it’s truly functional or not.
If it’s a sealed chamber then airflow doesn’t really matter. Just leave the filter system running long enough after the print finishes to have the air clean when you finally open the door.
Sure, but how do I know “how long is long enough”? That’s kind of my main concern.
Open the door and sniff lol. For filters that are 100% efficient at removing contaminants you only need to flow the volume of the chamber once through them. In reality it will take a few times. So chamber volume divided by the cfm of the filter fan is how long to complete one air change.
Right, seems elementary, but I missed that thought…
Its not going to work because the fumes are from the heated plastic, which the heated plastic does not end up in the filter. The plastic will continue to off gas until its cold again. Your filter may not actually work because you have no idea on how small to grind the charcol and active filter to capture that odor.
I’m going to suggest another approach. Build your box to house the 3d printer, but use a proper 3M respirator cartridge that will filter the fumes. Just attch the filter end to a proper connector, from a surplus mask, and then connect to a vacuum so the airflow goes through the filter.
The cartridges belong to 3M’s 6000 line, and others are available. What I would do is place one filter at the top of the box, and one at the bottom. This will capture the lighter than air, and heavier than air fume components.
https://www.tmart.com/6200-Dual-Canister-Gas-Mask-Chemical-Filter-Protection-Mask-Respirator-Gray_p352721.html
I was planning on buying HEPA+active charcoal filter, yeah, not going to make my own filters. There’s a number of sources for those I found.
The best approach is actually to use a very efficient filter (like a respirator cartridge) and exhaust a moderate amount of filtered air OUT of the printer, rather than trying to recirculate. That creates a little negative pressure to keep the smell inside the enclosure. Whereas if you recirculate, every tiny little air leak will let smell out, and you end up needing a practically airtight printer or a drastically higher power fan to capture all the fumes faster than they can leak.
Exhausting filtered air out does suck some heat from the enclosure, but you don’t need much airflow and it doesn’t make a big difference in chamber temp in my experience.
Can one print prosthesis with a 3D printer?
@Ryan_Carlyle yeah I’m not significantly worried about the heat loss inside the enclosure at this point. I was thinking of doing exactly what you say, with a very small opening somewhere to guarantee minimum airflow.
Just remember, that’s assuming the filter is 100% efficient at removing contaminants. Anything less and you will vent smells. If you do want to vent a small portion of air I would suggest having an additional filter on the vent output. It doesn’t need to be high flow since any airflow through it still gives you a negative pressure in the chamber.
@michael_hillpot yeah, that’s why a proper respirator cartridge is necessary for negative pressure venting approaches rather than a homemade charcoal filter or whatever. They are designed for very high absorption of contaminants (like 99 to 99.9%) in a short residence time. I use an “organic vapor” cartridge for ABS printing and it’s highly effective at knocking the smell down until the cartridge is saturated. It does require an exhaust fan with high static pressure though.
Thanks for all the feedback guys, I appreciate it. I’ll be sure to take everything into account and post the enclosure design I come up with in the show & tell section.