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Is there a cheap&compact fume extractor better than a bare 120 mm fan?

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beanflying:

--- Quote from: thm_w on February 27, 2024, 11:53:21 pm ---
--- Quote from: beanflying on February 27, 2024, 08:26:13 am ---Still running a slightly tweaked version of this prototype I made a few years ago. Two layers of activated charcoal and I don't run anything generally other than 60/40 Leaded. 12V DC fan typically running about 1.5-3W so 6-7V for this result and low noise.

--- End quote ---

Yes, as was discussed, activated charcoal doesn't do anything to 90%+ of what passes through that filter.
Its just getting smoke away from your face, which is fine if thats all you want.

--- End quote ---

You were WRONG last time we discussed this. Activated Carbon absorbs the VOC's ! The two layers of CLOTH are not perfect and I don't include the foam type of filters which are much less so.

Also to note here the OP and me and a bunch of contributors here are at 'Hobby Level' soldering when it comes to exposure.

thm_w:
Interesting selective memory. I won't re-write what I've covered it in the previous thread with citations: https://www.eevblog.com/forum/reviews/fume-extractor-advice/msg4890236/#msg4890236

Low restriction means a lower rate of filtering. If you want to properly filter VOC's you need: a thick layer of carbon where air cannot easily go around and avoid it, and a large mass of carbon material.
Without a HEPA prefilter you'll also clog up the carbon foam with large dust particles, which means even less VOC absorbed than would be expected.

If you want actually effective VOC filtration, you can get a hydroponics filter for ~$30 which has 2kg+ of carbon inside: https://www.amazon.com/Vanleno-Australia-Charcoal-Prefilter-Hydroponics/dp/B085DMC2LX/ref

SteveyG:
I am still running a Xiaomi air purifier in my lab which I covered briefly in a video over 4 years ago now  :o. It moves a lot of air and with the purple filter it does a great job of handling solder fumes. They're also reasonably quiet because of the large fan.

Swake:

--- Quote from: beanflying on February 27, 2024, 11:57:49 pm ---You were WRONG last time we discussed this. Activated Carbon absorbs the VOC's !

--- End quote ---
Your statement is false when it comes to the toxic particles in solder fume. These particles are smaller than what activated carbon can absorb. Whatever the form of that activated carbon foam; pellets; granules; powder; etc... 'Good' quality activated carbon can absorb particles down to 0,5┬Ám (=500nm). The toxic chemicals in the solder fumes however have a size of 20 to 150nm. In other words the vast majority of these particles will fly trough totally unfiltered.

The only thing that happens with an active foam re-circulation filter is that the particles are now all over the place and you're guaranteed to breath them in for much longer.


--- Quote from: SteveyG on February 28, 2024, 09:50:22 am ---I am still running a Xiaomi air purifier in my lab
--- End quote ---
To filter solder fumes this thing is absolute garbage. They state themselves that it only filters down to 300nm (=due to the HEPA filter).


The most harmful particles in solder fume are actually much smaller than what you can see. Again, extraction is the only good and cheap way to go.

thm_w:

--- Quote from: Swake on February 29, 2024, 12:11:09 pm ---To filter solder fumes this thing is absolute garbage. They state themselves that it only filters down to 300nm (=due to the HEPA filter).

The most harmful particles in solder fume are actually much smaller than what you can see. Again, extraction is the only good and cheap way to go.

--- End quote ---

It filters 99% of 0.3um, that does not mean it will not filter out a 0.2nm particle by definition. Its just a reduced probability:
https://www.researchgate.net/figure/Particle-size-dependent-filtration-efficiencies-of-FERENA-and-HEPA-filters-Data-were_fig2_325801518
https://www.researchgate.net/figure/Typical-performance-of-a-HEPA-999-filter_fig2_242434719

"absolute garbage" is a massive overstatement. Even in the worst case its capturing the vast majority of the particles. That said, I personally avoided xiaomi filters because it is very easy to buy counterfeit ones, so hard to know if they are genuine or not, or even if the originals are tested to the same degree western brands were.

Here is a particle density function for cigarette smoke: https://www.researchgate.net/figure/Particle-Size-distributions-from-mainstream-and-sidestream-ETS-1R5F-cigarettes-form_fig1_239791820 I didn't find one for solder fumes, but I assume similar.

If you want ultimate low particle size filtration you'd add electrostatic precipitator, as Dave has in the blueair unit.

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