Is there a cheap&compact fume extractor better than a bare 120 mm fan? - Page 1
Forum section: electronics / general

author: shapirus
author_rank: Super Contributor
timestamp: February 22, 2024, 10:18:50 am
content: So basically I'm using a bare 120 mm fan to pull the fumes away from the soldering area to reduce the concentration of harmful substances in the immediate vicinity of my face.Of course, no filtering takes place, and everything stays in the same room, the fan only helps to mix the fumes into a larger volume of air, which is removed from time to time by opening the window (or keeping it always open in the summer).I was wondering whether there are any cheap(ish) fume extractors, say under $100, of those typically encountered on Aliexpress, that would be compact (table-top), preferably not too loud and offer some kind of filtering that would actually work well enough to make replacing the fan with such a device worthwhile. There has to be a good improvement over the fan, otherwise it'll make it pointless.Cheap, compact, and simple are key points. I'm not looking for a fancy air filtering system that uses chemicals that you buy in bags etc., as was discussed in one of earlier threads.Can anyone share their personal experience?

author: thm_w
author_rank: Super Contributor
timestamp: February 22, 2024, 11:32:38 pm
content: We've had many threads where this has been covered, please read the existing ones first.Use a HEPA rated filter. Decent units can be sourced as low as $10-25.https://www.eevblog.com/forum/chat/hepa-filters-and-fans/https://www.eevblog.com/forum/reviews/(my-diy)-smoke-absorver-filtering-for-soldering/https://www.eevblog.com/forum/projects/diy-20lt-drum-solder-fume-extractor-(hepa-active-carbon)/https://www.eevblog.com/forum/reviews/fume-extractor-advice/https://www.eevblog.com/forum/beginners/pwm-fan-frequency-different-from-speed-controller-frequency/https://www.eevblog.com/forum/projects/diy-high-performance-solder-fume-extractor/https://www.eevblog.com/forum/projects/homemade-hepa-solder-fume-extractor/

author: shapirus
author_rank: Super Contributor
timestamp: February 23, 2024, 12:33:54 am
content: Quote from: thm_w on February 22, 2024, 11:32:38 pmI did.Quote from: thm_w on February 22, 2024, 11:32:38 pmI don't need just a filter. I am looking for a ready made device.Quote from: thm_w on February 22, 2024, 11:32:38 pmNone of these topics are exactly relevant. I did read them. I'm not interested in DIYing anything beyond a bare fan which I already use, neither am I interested in buying a professional device. All I'm looking for is something cheap, compact, and much better than a fan. It's fine if it does not exist. If it does, however, I'll be happy to hear about good experience with specific products, if anyone has information to share. New chinese models appear all the time, and there's a chance that some of them may be sufficiently above useless.

author: thm_w
author_rank: Super Contributor
timestamp: February 23, 2024, 01:19:16 am
content: Experience is near meaningless without measurements. No one who is capable of measuring the particulate filtering efficiency will bother to buy a <$100 no-name product.Fake chinese hepa/carbon filters are notorious. Its up to you if you want to trust a no name brand when you can get genuine branded HEPA filters for <$30.When you blow the fumes away with the fan, without an open window, they will sit in the air in your room for hours on end. If you receive a fake HEPA filter, maybe some of the particles will be captured, maybe not.https://www.aliexpress.us/item/3256806224762083.htmlhttps://www.aliexpress.us/item/3256805139294606.htmlhttps://www.aliexpress.us/item/3256804872965831.html(not HEPA just says N95)https://www.aliexpress.us/item/3256806000964633.html(best value)

author: Swake
author_rank: Frequent Contributor
timestamp: February 26, 2024, 09:41:33 pm
content: Having similar needs as the OP I recently did some digging in research papers on the subject.In the end I opted for fume extraction through to outside instead of filtration as that is much simpler and cheaper.Here is what I found during the research:- What you want to filter out of those solder fumes comes in the form of both very small particles and gas vapors.- Active carbon filters are near worthless as most toxic particles found in solder fumes are smaller than what an active carbon filter can filter out.- HEPA filters will effectively filter out the particles for +99% (not the gas vapor). However these filters must be of the certified type and be well maintained. -> don't buy the cheap stuff, those are not performing as expected.- Chemical capturing filters that can capture the specific gas vapors of solder fumes are difficult to identify, find, implement and maintain. I'm not a specialist in this matter and it was still unclear how well these would filter those gas vapors and when it would be required to replace the filters.- A good set of filters will represent an important resistance to airflow. Hence the need for a relatively powerful fan and filters with as large a filtration surface as possible to reduce the resistance.- Anything ready made with the above specs costs a fortune.

author: Whales
author_rank: Super Contributor
timestamp: February 26, 2024, 10:53:04 pm
content: Quote from: Swake on February 26, 2024, 09:41:33 pmI used to do this and it worked brilliantly. A mixture of stormwater pipe, 120mm computer fan, sheets of paper and sticky tape going to an air vent in the wall.I've since re-organised my lab and don't have it any more. Really miss it, just using the 120mm fan to "stir" air isn't enough. I need to rebuild it.

author: thm_w
author_rank: Super Contributor
timestamp: February 26, 2024, 11:06:02 pm
content: Quote from: Swake on February 26, 2024, 09:41:33 pmSure, but most hobbyist level soldering does not create large amounts of gas vapors that need to be captured. So you can get away with HEPA filtration capturing 95% of the crap, and living with that remaining 5%. If you are concerned about the gas vapors (working with heavy solvents, melting plastics, sensitive lungs, etc.) then yes vent outside or work outside, is the lowest cost option.What I did was drill holes in the wall, install a dryer vent exhaust, and vent through that.If you don't want to drill the wall then a window plate can be used, many have done this for their portable air conditioners. Cost about $30-40 for a window kit.

author: Swake
author_rank: Frequent Contributor
timestamp: February 27, 2024, 08:12:23 am
content: You are right, the word 'hobby' is important here. Keep a door and a window open to create a bit of airflow during the soldering and for 15 more minutes after the soldering to refresh the air and that is an immense improvement. During winter conditions with freezing temperatures this might be more challenging of course.

author: beanflying
author_rank: Super Contributor
timestamp: February 27, 2024, 08:26:13 am
content: 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.You can put whatever you like between the front frame and slightly more rear frame between 5 and 6mm compressed or more I guess if you wanted. 120mm Fan used.

author: thm_w
author_rank: Super Contributor
timestamp: February 27, 2024, 11:53:21 pm
content: Quote from: beanflying on February 27, 2024, 08:26:13 amYes, 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.

author: beanflying
author_rank: Super Contributor
timestamp: February 27, 2024, 11:57:49 pm
content: Quote from: thm_w on February 27, 2024, 11:53:21 pmYou 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.

author: thm_w
author_rank: Super Contributor
timestamp: February 28, 2024, 12:43:30 am
content: 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/#msg4890236Low 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

author: SteveyG
author_rank: Unknown
timestamp: February 28, 2024, 09:50:22 am
content: I am still running a Xiaomi air purifier in my lab which I covered briefly in a video over 4 years ago now. 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.

author: Swake
author_rank: Frequent Contributor
timestamp: February 29, 2024, 12:11:09 pm
content: Quote from: beanflying on February 27, 2024, 11:57:49 pmYour 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 0,5µm (=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 amTo 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.

author: thm_w
author_rank: Super Contributor
timestamp: February 29, 2024, 11:33:40 pm
content: Quote from: Swake on February 29, 2024, 12:11:09 pmIt 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_325801518https://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_239791820I 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.