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I want to make a small air filter using standard axial pc fans in order to suck smoke like that have been produced in soldering process.

But I assume filtering will make it difficult. Am i wrong? The air have to be forced through the granulated carbon filter.

I researched about radial fans which produced spesifically for this job(suction), but they have disadvantages like price, vibration and noise. They are at least 60dba. May not suitable to be used in room.

My main purpose is increasing suction of air, not the air flow. I can go with minor flow. (if my expression is not true please correct)

The question is, can a group of fan in same direction, increase the suction of air? Can it force the air to pass through carbon filter about 1-2cm thickness?

enter image description here

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    $\begingroup$ Fans placed in series on a closed system will increase your pressure of the fan curve with little increase in your volume. Carbon filters have benefits but if you can vent to fresh air and just dilute your small vapors it will be cheaper and more reliable. $\endgroup$
    – Dopeybob435
    Aug 8, 2016 at 15:02
  • $\begingroup$ @Dopeybob435 wouldn't the volume be roughly proportional to the pressure, to a point? $\endgroup$
    – Jodes
    Aug 8, 2016 at 18:33
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    $\begingroup$ The proportion of volume vs pressure is determined by the fan curve. There are so many possibilities for what the system could be depending on which fan designs are used (many more decisions than just centrifugal vs axial.) Link may provide more info. greenheck.com/library/articles/42 I also found an example fan chart for CPU fans (internation units) coolingtechnique.com/img/rece/ventole-rheobus/corsair/… $\endgroup$
    – Dopeybob435
    Aug 9, 2016 at 3:11
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    $\begingroup$ Correct, fans in series will increase the static pressure and how many are necessary will depend on @mart 's question regarding the pressure loss expected by the carbon filter. If the filter is made by someone else they may have loss data or if custom use trial and error (guess and check). Vent to fresh air means exhaust the fumes outside (upper half of image energy.gov/sites/prod/files/styles/large/public/… ) $\endgroup$
    – Dopeybob435
    Aug 9, 2016 at 11:38
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    $\begingroup$ Put the fans in parallel, not series. But as Dopebob points out, venting to the exterior is far more sensible. The undesirable specie in solder smoke are harmless once diluted. I'm also rather skeptical that a carbon filter will appreciably reduce the concentration of the gases in question. $\endgroup$
    – Carl Witthoft
    Aug 9, 2016 at 14:18

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Fans in series will increase the maximum effective pressure. If the filter is of high resistance this will result in an increase in flow for the system. If there is negligible resistance, like if the filter was taken out, one fan will have the same flow rate as 3 fans in series. There is a lot going on here that will be too much to explain in one question. I recommend reading on fan curves, maximum pressure and maximum flow rate if you would like to broaden your understanding.

Zoro.com does a good job of posting engineering specifications for the fans and blowers they sell.

For your product design; solder fans already exist. If you would rather build your own I recommend gleaning some information from their designs like the light weight filter they use or fan dimensions and flow rates.

Soldering fan on amazon, 1
Soldering fan on amazon, 2 solder fan

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  • $\begingroup$ In fact, I could not find product like this where I live, Turkey. I saw a few times as non-stock. Even if they were in stock it is highly expensive for its value. As I remember approximately 250Turkish Liras, about 1/5 of the minimum wage. Importing from sites like amazon costs more because of exchange rate, customs tax, shipping price and storage fee. Maybe it can be found with hard searching but I would need at least 2 for my soldering station and soldering pot. Tunnel with 2-3 inlets better but needs high pressure I guess. Maybe I will go with 300pa radial fan if I tolerate noise $\endgroup$
    – Alnus
    Aug 15, 2016 at 8:02
  • $\begingroup$ On a budget, just a fan blowing the smoke away will be a major improvement. You may also want to checkout aliexpress; mostly Chinese manufacturing and ships worldwide: aliexpress.com/… $\endgroup$
    – ericnutsch
    Aug 15, 2016 at 22:52
  • $\begingroup$ But it is not a workshop, it is room including my bed.:/ Doesn't blowing away keeps the harmful contamination in the air? I want to clear air as much as possible because I cannot vent to fresh air especially in winter. $\endgroup$
    – Alnus
    Aug 16, 2016 at 6:13
  • $\begingroup$ Well, a thin carbon filter will help, but it is by no means going to make the air fresh. A healthy living/work environment should have the ability have some amount of ventilation. This is important for more than just soldering. To recover heat lost from ventilation in the winter look at "air exchangers" google.com/… $\endgroup$
    – ericnutsch
    Aug 17, 2016 at 14:36
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The short answer is yes, but they will be much more effective if they turn it opposite directions, or have straightening vanes between to take the spin out of the air.

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@Dopeybob435 have gave the answer that I need.

Fans placed in series on a closed system will increase your pressure of the fan curve with little increase in your volume

I understand the static pressure and airflow. I needed pressure so I bought a single radial fan that have 300ps pressure capacity, regarding the noice factor (50db). I still don't know the resistance of granular carbon that amount I am using. But it works just fine, for now.

Thank you all.

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