DIY 20lt Drum Solder Fume Extractor (HEPA / Active Carbon)

[GotZapped]

DIY 20lt Drum Solder Fume Extractor (HEPA / Active Carbon).


I wanted a solder fume extractor to reduce or eliminate the toxins from soldering inside the house or garage. Even with a window open or fan it does not help much. I had a small fan with activated charcoal foam filter but they are not really effective [1], [2].

Dave’s entertaining video [https://www.eevblog.com/forum/blog/eevblog-1305-hepa-solder-fume-extractor/] sparked my interested in getting the “Kingsom KS-180 HEPA flexible arm solder fume extractor” but the shipping costs killed the deal. It was >$500AUD for the unit including shipping and obtaining replacement filters was not clear at the time.

Whilst units from Weller or Hakko are nice units, but very expensive for the hobbyist as they are over $1,000AUD and the replacement filters are in the $100’s.

Leading me to look at a bunch of DIY solutions [3]–[6], but I found them either overly complex or I could see room for improvement.

Inspired by those creative people who shared their fume extractor ideas over the years. I’ve come up with what I hope is an easy to build solder fume extractor. My goals for building the extractor were:

- Use off-the-self components that are easily available and cheap(ish).
- Be simple to build with minimal amount of tools.
- Use readily available and cheap filters (HEPA and active carbon).

The cost for my one-off build was roughly $580AUD with all new parts. Indeed it was about the same as the Kingsom fume extractor. However, I used a high quality centrifugal fan (~$200) and modular anti-static Loc-Line hoses (~$150). I could have used a smaller fan or sourced a cheaper fan and the Loc-Line was for my “deluxe” model Plus it was a learning experience which is priceless

I’m really happy to hear feedback and hope some brave soles try to build this. Or this is the wrong approach? This is a “free and open source” hardware project so we can share and build on this idea.


OVERVIEW


The fume extractor consists of 1) the 20lt drum filter and 2) the axial fan mounted on the side of my shelves. They are connected by 150mm diameter ducting secured by Noise Reducing 150mm/6 inch Connector Fan Clamps at each end. I was going to mount the fan directly to the drum, but opted not to as it would be top heavy. I use a small variac to control the speed of the fan (not shown).



Close up of the drum: the photo shows the inlet is feed by a 100mm duct secured with a Noise Reducing 100mm/4 inch Connector Fan Clamp.



Close up of the fan mounted to the shelves.



Photo of the Loc-Line mounted underneath the shelves. I used a 100mm square floor grate (plumbing) to connect the 100mm ducting to the Loc-Line assembly.

Post 1 of 4 (due to file size limits)

Sorry I cannot get the inline images to work yet.

[GotZapped]

Filter Selection

For the filter I selected the Xiaomi Mi Air Purifier Formaldehyde Antibacterial Filter (Fits the Xaiomi 1/2/Pro/2S/3 Air purifiers). This is the purple coloured filter with an inner carbon filter, but the outer purple filter is not HEPA. I decided to buy the HEPA filter (grey colour) and insert the Carbon filter from the purple filter. I’m not sure if the there is a sufficient difference in filter performance to do this.
 
The Xiaomi Mi filters are readily available and relatively cheap ~$30-40AUD each when on sale. I use the surplus purple filter in my Xiaomi Air purifier so it does not go to waste.

Fan Selection

I wanted to find a similar centrifugal fan as shown in Dave’s tear-down video of the Kingsom https://www.eevblog.com/forum/blog/eevblog-1305-hepa-solder-fume-extractor/msg3189134/#msg3189134. Unfortunately I didn’t find a solution so I picked a centrifugal axial fan instead.


Bill of Materials (BOM)

Item	URL example	Qty	$/each	Subtotal
20lt Drum with Lid and Lock Ring	https://www.directpaint.com.au/brushes-rollers/paint-pots/20lt-drum-with-lid-and-lock-ring.html	1	$25	$25
Centrifugal fan (Can-Fan RS 150mm)	https://www.eppinghydroponics.com.au/products/0af7b240-abb9-11ea-fb5b-1bbf1de53d50	1	$200	$200
Starting Collar Square 150mm/6inch	https://www.eppinghydroponics.com.au/collections/starting-collars/products/0af7b240-abb9-11ea-fb5b-1bc0d90034c9	1	$25	$25
100mm Silver Duct 6m Length	https://www.eppinghydroponics.com.au/collections/ducting	1	$13	$13
150mm Silver Duct 6m Length	https://www.eppinghydroponics.com.au/collections/ducting	1	$15	$15
100mm PVC duct joiner		1	$8	$8
Noise Reducing 100mm/4 inch Connector Fan Clamp	https://www.eppinghydroponics.com.au/collections/clamps	1	$10	$10
Noise Reducing 150mm/6 inch Connector Fan Clamp	https://www.eppinghydroponics.com.au/collections/clamps	2	$10	$20
450 x 450mm x 3mm Black Rubber Adhesive Mat	https://www.bunnings.com.au/moroday-450-x-450mm-x-3mm-black-rubber-adhesive-mat_p0011948	1	$8	$8
4.5 x 50mm Ring bolts	https://www.bunnings.com.au/taskmaster-4-5-x-57mm-316-stainless-steel-eye-bolt-2-pack_p0237994	4	$3	$12
4.5mm nuts		4	$1	$4
5mm washer		8	$1	$8
100mm x 100mm Tin can	T2 tea leaves container	1	$0	$0
Modular Loc-Line 2.5” Anti-static hoses and fittings.	https://www.modularhose.com/loc-line-25-system/25-anti-static OR https://hakkousa.com/catalogsearch/result/?q=loc+line	1	$150	$150
Small Elastic Bungee straps with hooks		1	$5	$5
150mm diameter flower pot saucer		1	$3	$3
Xiaomi Mi Air Purifier Formaldehyde Antibacterial Filter for 1/2/Pro/2S/3		1	$40	$40
Xiaomi Mi Air Purifier HEPA Filter for 1/2/Pro/2S/3		1	$40	$40
Rivets		1	$0	$0
Sealant		1	$0	$0
Misc mounting hardware		1	$0	$0
Total				$586

TOOLS

Drill
Drill bits
Jigsaw
Rivet Gun
Left-handed (or right-handed) tin snips
Straight tin snips
Box cutter
Caulking gun
Spanner
Screw driver

CONSTRUCTION

1. Filter Assembly
The exploded diagram below shows the components of the filter assembly (the elastic straps not shown).



        1.1. Lid
            1.1.1. Find centre of steel lid and mark a 150mm diameter circle.



            1.1.2. Drill 12mm hole just inside the circle and use the left handed tin snips to cut out circle. Sorry about the poor photo.



        1.2. Starting Collar spacer
            1.2.1. Depending on the collar size, cut a piece of wood to size and add a taper along the edges to match the tapper on the collar.
               


            1.2.2. Mark the centre of the wood spacer and draw a 150mm circle.
               
            1.2.3. Drill a 12mm hole inside the circle and use a jigsaw to cut the circle out.

            1.2.4. Tapper the edges as the Starting Collar had slopping edges. Sand to clean up.


        1.3. Gasket
            1.3.1. To make the gasket, mark out the inner diameter on the Black Rubber Adhesive Mat using the filter base as a template. Then mark the inner 150mm diameter circle.
            1.3.2. Cut the inner circle out and trim the outside of the mat using strong scissors or box cutter.



        1.4.  Assembly
            1.4.1. Mark (centre punch if needed) the location of the four bolt locations in the starting collar near the corners of the sheet metal.
            1.4.2. Drill 5mm holes in each corner of the starting collar.



            1.4.3. Using a clamp or vice, use the collar as a template to drill the wooden spacer.
            1.4.4. Now carefully align the collar space onto the lid and mark the location of four bolts for drilling.


            1.4.5. Drill four 5mm holes in the 20lt lid.


            1.4.6. Stick the rubber seal onto the lid.


Post 2 of 4

[GotZapped]

1.4.7. Place the Xiaomi filter on to the seal with the pot saucer.
1.4.8. Secure with the four elastic bungee straps. I had to add a few knots to get enough tension on the straps.




    2. 20lt Drum Assembly
The exploded diagram below shows the design of the 20lt drum assembly.


        2.1. Using a square tin can (T2 tea in this case) that will accept the 100mm ducting joiner, trace out the lines as shown below using the bottom of the 20lt drum as a guide.
        2.2. Cut top section of tin can, leave an extra lip for it to be secured to the bottom and sides of the drum.



        2.3. Trace out the hole to be cut in the side of the drum using the tin-can as a guide.
        2.4. Cut out the section by drilling a starter hole and using the tin snips.



        2.5. Cut and fold the extra lip of the tin-can to form petals to over lap the curved section.




Post 3 of 4

[GotZapped]

Continued from previous post.



2.6. Drill and rivet the tin-can to the drum.





2.7. Caulk using sealant all gaps between tin-can/drum and tin-can/100mm duct joiner.

Thanks for watching 

References
[1]   ‘Are filtered solder fumes safe?’, Electrical Engineering Stack Exchange, Feb. 02, 2021. https://electronics.stackexchange.com/q/546070
[2]   A. E. Johnson and R. C. Brown, ‘Measurement of the performance of air cleaners against the particulate element of rosin-based solder flux fume’, Ann. Occup. Hyg., vol. 42, no. 8, pp. 511–519, Nov. 1998, doi: 10.1016/s0003-4878(98)00060-x.
[3]   ‘Making a solder fume extractor filter’. https://www.flameport.com/projects/solder_fume_extractor/index.cs4
[4]   By, ‘DIY Fume Extractor Keeps Air Clean While You Solder’, Hackaday, Jul. 20, 2021. https://hackaday.com/2021/07/20/diy-fume-extractor-keeps-air-clean-while-you-solder/.
[5]   ‘DIY high performance solder fume extractor’, Kevin Aghaei’s Lab, Mar. 07, 2021. https://neonkev.com/2021/03/07/diy-high-performance-solder-fume-extractor/ .
[6]   ‘Building a Low Cost Solder Fume Extractor – Part 1’, Oct. 27, 2017. https://www.element14.com/community/groups/open-source-hardware/blog/2017/10/27/building-a-low-cost-solder-fume-extractor-part-1

Post 4 of 4

[tatel]

Hi.

You said "centrifugal fan" but it looks axial to me: https://en.wikipedia.org/wiki/Centrifugal_fan

IIRC, centrifugal fans can work at higher pressures so they would be better for work with filters. But axial fans are said to be lees noisy, so not bad. However I think you should look at the drum placement, so pipes go as straigth as possible. You don't want any elbows if at all possible. Elbows will greatly reduce fan performance, and it seems the drum/filter assemby is the best way to do the only 90º elbow you need.  I can't see why you would need to have that 180º elbow. Probably you could get rid of it by just rotating the drum. That would help improve fan performance and you could probably make the fan spin at lower RMP, reducing the noise even more.

[GotZapped]

Hi tatel,

You said "centrifugal fan" but it looks axial to me: https://en.wikipedia.org/wiki/Centrifugal_fan

Indeed it looks like an axial fan, but the specs for the fan say it is a "Centrifugal Inline tube fan" and the photos show what looks like a centrifugal fan [1]. ... unless it's just marketing

... I can't see why you would need to have that 180º elbow. Probably you could get rid of it by just rotating the drum. That would help improve fan performance and you could probably make the fan spin at lower RMP, reducing the noise even more.

100% agree, but the shelving frame and equipment on the bench is in the way, so I had to do the 180º U-turn which is not ideal.

I could have put the inlet port near the top of the drum, instead of the bottom. Then I could rotate the drum around like you suggested. Maybe for Mark II, but it depends how each persons work space is setup I guess.

1. https://www.eppinghydroponics.com.au/products/0af7b240-abb9-11ea-fb5b-1bbf1de53d50

[Shay]

That's neat. But I am not getting exactly, why spending so much on fume extractor for a hobbyist is worth it. Unless there is any health issues, or you are soldering 24/7, a simple fan blowing across the room should be fine? Walking in the street for a few minutes near a busy road probably has more car gas emissions inhaled than soldering for a day. (Correct me if I am wrong).
I personally solder a lot in my work, and I just use a fan to blow across the table. It seems to work fine and I can definitely notice the difference without the fan, as the flux flumes feel just nasty.

[GotZapped]

Hi Shay,

Thanks Shay.

The fumes from soldering is definitely a health issue. A fan will only blow the toxic fumes around the room, even with a window open they don't escape. I noticed it especially when I did some light soldering, left the room and came back...I could really smell it.

I don't do a lot of soldering, but when desoldering components from vintage equipment the smell is appalling. I'm sure it's not good to breath in.

It's just a precaution and I found my diy solder fume filter really does remove the smell. If I don't turn it on the odour is definitely there.

I plan to use a PM2.5 particle sensor or volatile gases sensor at the exhaust to measure the air quality so I know when to replace the filter. I was thinking of using the sensor / electronics from the ANAVI fume extractor (https://www.crowdsupply.com/anavi-technology/fume-extractor).

[thm_w]

Yes this is a good build, we have some relevant threads:
https://www.eevblog.com/forum/reviews/fume-extractor-advice/
https://www.eevblog.com/forum/blog/eevblog-1305-hepa-solder-fume-extractor/
https://www.eevblog.com/forum/reviews/fume-extractor-222760/

My only concern here is the Xiaomi filter is commonly counterfeited, so you may be cautious about getting a real one. Supposedly real is HEPA H13 rated.

That's neat. But I am not getting exactly, why spending so much on fume extractor for a hobbyist is worth it. Unless there is any health issues, or you are soldering 24/7, a simple fan blowing across the room should be fine? Walking in the street for a few minutes near a busy road probably has more car gas emissions inhaled than soldering for a day. (Correct me if I am wrong).
I personally solder a lot in my work, and I just use a fan to blow across the table. It seems to work fine and I can definitely notice the difference without the fan, as the flux flumes feel just nasty.

Hobby sure. If you are doing this regularly for work, get a proper fume extractor or ventilation. You're sacrificing your health over a few hundred dollars of money that is not even yours.
"It seems to work fine" doesn't mean much. The fan pushes that smokey air and it just sits in the room, as GotZapped stated. If you measure with a particle sensor it will reveal reality (that the air quality is bad).

BTW that Anavi project is a bit of a joke, its not even filtering the air so monitoring is odd.
You can find much better sensors than what is used there (PMSA003, PMS7003, etc.), if you have the budget.