DIY fume extractor with PWM control
« on: October 30, 2020, 06:34:21 AM »
This topic is not directly related to audio so I thought that probably the "Machine shop" is the right section but please feel free to move it if necessary  :)

I need to make a fume extraction system since I do quite a bit of soldering and I think I've inhaled enough fumes for 2-3 lifetimes...

I have already drilled a hole in my workshop's wall that is directly connected to a chimney so all the fumes will be extracted outdoors instead of using filters. The idea is to use a 12VDC inline fan connected to one of these PWM controllers you can find online that are used for DC motors and LEDs.

I think I'll get one of the following fans. I just haven't decided yet on how many CFM I would need. http://www.seaflo.com/en-us/product/list/321.html Obviously these are 2-wire DC fans.

I'm wondering if someone has attempted something similar and if so I would really appreciate some advice!

The main questions that arise from such a project are:

a) How many CFM would be appropriate?

b) Will these 2-wire fans work with a PWM controller and if so what would be a good PWM frequency? I have found some 3kHz and some 20kHz PWM controllers 

c) Are there any other issues that I should consider by doing such a project?


FWIW, I'll most likely be using loc-line 2.5" vacuum system. Either the simple one or the anti-static one.

As I already said, any advice would be much appreciated!  :)
« Last Edit: October 30, 2020, 07:40:17 AM by warpie »


abbey road d enfer

Re: DIY fume extractor
« Reply #1 on: October 30, 2020, 07:05:00 AM »
This topic is not directly related to audio so I thought that probably the "Machine shop" is the right section but please feel free to move it if necessary  :)

I need to make a fume extraction system since I do quite a bit of soldering and I think I've inhaled enough fumes for 2-3 lifetimes...

I have already drilled a hole in my workshop's wall that is directly connected to a chimney so all the fumes will be extracted outdoors instead of using filters. The idea is to use a 12VDC inline fan connected to one of these PWM controllers you can find online that are used for DC motors and LEDs.

I think I'll get one of the following fans. I just haven't decided yet on how many CFM I would need. http://www.seaflo.com/en-us/product/list/321.html Obviously these are 2-wire DC fans.

I'm wondering if someone has attempted something similar and if so I would really appreciate some advice!

The main questions that arise from such a project are:

a) How many CFM would be appropriate?

b) Will these 2-wire fans work with a PWM controller and if so what would be a good PWM frequency? I have found some 3kHz and some 20kHz PWM controllers 

c) Are there any other issues that I should consider by doing such a project?


FWIW, I'll most likely be using loc-line 2.5" vacuum system. Either the simple one or the anti-static one.

As I already said, any advice would be much appreciated!  :)
I suggest you consult the datasheets for dedicated systems, such as :
https://docs.rs-online.com/75c2/0900766b80641a0e.pdf
https://docs.rs-online.com/8320/0900766b81561aa1.pdf
The CFM depends very much on the collector and the presence/absence of filter.
In-line fans tend to be noisy, they should be used in conjunction with a sound trap.
I woould have a look at those 8" silent fans.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Re: DIY fume extractor
« Reply #2 on: October 30, 2020, 07:39:51 AM »
I suggest you consult the datasheets for dedicated systems, such as :
https://docs.rs-online.com/75c2/0900766b80641a0e.pdf
https://docs.rs-online.com/8320/0900766b81561aa1.pdf
The CFM depends very much on the collector and the presence/absence of filter.
In-line fans tend to be noisy, they should be used in conjunction with a sound trap.
I woould have a look at those 8" silent fans.

Noise shouldn't be a problem. Since the fan will be permanently attached to the wall I can build an mdf box with absorption inside to tame the noise I guess .

Unfortunately an 8" fan is not an option because the width of the chimney is only 4".

I'm mostly concerned with the PWM controller to adjust the speed of such fans. For example if the fans need at least 7-8V to start operating, such a controller might not be adequate.

Another option I'm looking into is to use one of the two follwoing fans

https://www.amazon.com/TerraBloom-Adjustable-Ventilation-Hydroponics-Boosting/dp/B07JNGS2V7

or

https://www.amazon.com/gp/product/B07JB292JC/ref=ox_sc_act_title_1?smid=A2AW0W4FKP16S5&psc=1

These have already built-in PWM control, they are brushless and mixed flow but I'm in Europe so it'll set me back more than €150 just for the fan. I can justify the cost if they are worth it but the problem is that if they are insufficient it'll be a total waste of money.

Re: DIY fume extractor with PWM control
« Reply #3 on: October 30, 2020, 09:27:33 AM »



Rob Flinn

Re: DIY fume extractor with PWM control
« Reply #6 on: November 03, 2020, 02:29:01 PM »
I don't really understand the need for PWM control.   You just need a fan that extracts the fumes, why do you need to control it's speed.  Seems like you're overcomplicating it to me ............
regards Rob

abbey road d enfer

Re: DIY fume extractor with PWM control
« Reply #7 on: November 04, 2020, 12:29:52 AM »
I don't really understand the need for PWM control.   You just need a fan that extracts the fumes, why do you need to control it's speed.  Seems like you're overcomplicating it to me ............
Most fans are very noisy. I think it's a good thing to be able to run them at lower speed when high flow is not needed. Just like you don't want your AC to run at max all the  time.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Rob Flinn

Re: DIY fume extractor with PWM control
« Reply #8 on: November 04, 2020, 05:27:06 AM »
Most fans are very noisy. I think it's a good thing to be able to run them at lower speed when high flow is not needed. Just like you don't want your AC to run at max all the  time.

Maybe, but you can buy silent fans (e.g Noctua NF-S12B redux-1200), & also it's not like he's doing this while trying to master some classical chamber music so is noise over saving ones health more important.   
regards Rob

abbey road d enfer

Re: DIY fume extractor with PWM control
« Reply #9 on: November 04, 2020, 11:28:57 AM »
Maybe, but you can buy silent fans (e.g Noctua NF-S12B redux-1200), & also it's not like he's doing this while trying to master some classical chamber music so is noise over saving ones health more important.
Noctua fans are typical 120 mm fans used in PC's. The OP wants an in-duct fan. Nothing wrong in wanting to work in a quiet environment. Silence is a significant factor in health.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.


Rob Flinn

Re: DIY fume extractor with PWM control
« Reply #10 on: November 04, 2020, 01:42:09 PM »
Noctua fans are typical 120 mm fans used in PC's. The OP wants an in-duct fan. Nothing wrong in wanting to work in a quiet environment. Silence is a significant factor in health.

To make it quiet just mount the fan at the other end of the duct ........
regards Rob

Re: DIY fume extractor with PWM control
« Reply #11 on: November 04, 2020, 05:02:39 PM »
The reason I'd rather go with an inline fan is that it'll be the easiest way to attach one end of the fan to the wall (where the chimney is) and the other end to the duct.

Also, PC fans have rather small CFM so I'm not sure whether they will work for this specific installation. I should say that the distance between the fan and the soldering area would be 1-2 meters. There will also be some simple filtering (probably something similar to what is being used on the kitchen hoods) just for protecting the blades from anything else other than fumes that might get sucked in.

So, I think that maybe a CFM in the range of 130 to 160 would be adequate but this is just an assumption. I really don't know whether it's too little or too much.

Another factor is that (inevitably) I'm gonna have to reduce the duct size from 4" (fan) to 2.5" (loc-line) and this affects quite a lot the performance and also increases noise.

Anyway, as I said I really don't know. I'm just thinking out loud and hoping for some recommendations.

Rob Flinn

Re: DIY fume extractor with PWM control
« Reply #12 on: November 04, 2020, 05:37:30 PM »
I use a small standalone unit with replaceable foam filters.   What is quite useful is that you can put it close to the work.    I'm not sure how it would work if it were 1 to 2  metres away from the work.   I think that if your fan is this distance away it will need to be pretty strong to work effectively.
regards Rob

Whoops

Re: DIY fume extractor with PWM control
« Reply #13 on: November 07, 2020, 07:37:21 PM »
No filters means that the crap will go somewhere and be deposited somewhere.

With filters it gets stuck/accumulated in the filter and you can replace it.

Even if you don't care about sending it to the air outside your workshop, have in mind that with no filtering the pipes you use will get really dirty, the fan will get dirty and if you do a lot of soldering it will accumulate and be hard to clean in the future.

You can see in this video at after 1:15 how much crap gets sucked in just 1 month of using:

https://www.youtube.com/watch?v=KAaM0z9JjYc&t=157s

I'm also building a Fume extractor, but I will use filters, in this case car carbon activated air/particle/cabin filters because they're cheap and easily available everywhere (if you choose a common car model), and I will use also Silent computer fans, like the ones from Noctua or Arctic.
I will use a footswitch to easily turn the extractor on/off while soldering.

Re: DIY fume extractor with PWM control
« Reply #14 on: November 08, 2020, 08:49:43 AM »
No filters means that the crap will go somewhere and be deposited somewhere.

With filters it gets stuck/accumulated in the filter and you can replace it.

Even if you don't care about sending it to the air outside your workshop, have in mind that with no filtering the pipes you use will get really dirty, the fan will get dirty and if you do a lot of soldering it will accumulate and be hard to clean in the future.

You can see in this video at after 1:15 how much crap gets sucked in just 1 month of using:

https://www.youtube.com/watch?v=KAaM0z9JjYc&t=157s

I'm also building a Fume extractor, but I will use filters, in this case car carbon activated air/particle/cabin filters because they're cheap and easily available everywhere (if you choose a common car model), and I will use also Silent computer fans, like the ones from Noctua or Arctic.
I will use a footswitch to easily turn the extractor on/off while soldering.

As I wrote before I will be using a filter for protecting the blades of the fan. I was thinking of using a general filter like the ones being used in cooking hoods but I might also consider your suggestion. However, in regards to extracting the fumes outdoors, I can't see how is that different from having a window open while soldering.


 

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