Why does smoke from a soldering iron ALWAYS go towards your face?

[EEVblog]

 

[pickle9000]

That was interesting.

[srb1954]

Would it help to to sit well back from the edge of the bench leaving a gap where air can flow upwards to fill the low pressure area?

[RoGeorge]

Didn't watch, but soldering smoke go towards face because of Bernoulli's Principle.
- body temperature is higher than the surrounding air, which creates ascendant currents near the human body
- in a fluid, the sum of pressures is constant, so if air moves, then the hydrodynamic pressure increases at the cost of hydrostatic pressure

- in simple words, the raising air heated by the human body creates suction around it, which drags in the smoke

[chriva]

That guy has way too much free time on his hands and it's awesome.
I bet most of us have been bothered by it so actually knowing why is neat.

[artag]

So rather than all those fans, filters etc, a tall triangular box on the far side of the soldering station and an intentional break in the barrier posed by my arms would take the smoke away ?

How does this map to the campfire problem, where the smoke preferentially follows me instead of anyone else ?
Note : I am not the width of three other cold campers.

[fanOfeeDIY]

Wow, he must have took a month for this video. Amazing.

I still not using any fan during soldering, I am going to make one for me.

[OwO]

A fan alone isn't enough, you need at least an activated charcoal filter (very cheap). No need to go with a full blown fume extractor with expensive HEPA filters unless you are doing production soldering.

[bill_c]

And here I was thinking it was just my negativity all this time...

[thm_w]

A fan alone isn't enough, you need at least an activated charcoal filter (very cheap). No need to go with a full blown fume extractor with expensive HEPA filters unless you are doing production soldering.

Disagree, a decent HEPA filter is $30 (just the filter replacement).
If you are soldering more than a few hours per week, and care about your health, you should have one. That or a way to exhaust outside.

[borjam]

Obvious. Any dangerous or even annoying object creates a Murphy's field around it!

[cdev]

Because your head and brain are a source of heat and the rising air around your body creates a draft that pulls smoke toward you especially if its lower. Like a fire would! 

OOPS- Dang-- looks like everybody else knew that too! Good.. 

Hey, at least I can contribute this. My laser level and various other tools that incorporate lasers use a piece of metal with tiny parallel lines of the right equal size to make a diffraction grating which creates a line useful for visualizing smoke in a plane, I've used use glycerine as a smoke fluid, with a bit of nichrome wire to heat it. You can use that to visualize air flows. Another quick and dirty way to visualize very small air flows is go to your local hardware store and pick up (0.5 mil thick plastic sheeting, i.e. the thinnest cheapest painters drop cloth you can find, its so thin it just floats on the smallest breze)  You can use this to find drafts and leaks very effectively.


What works for me for soldering best is a fan blowing fumes out the window, attached to a piece of flexible duct- and something to hold it in place near the work. This can be rigged up with any available large diamter tubing, but flexible ducting works best with a fairly powerful fan.

Once I set up a nice commercial window fan adding a sort of awning to keep rain out and could actually run this all the time and switch both its fans to blow in or out or exchange air. It was competely protected from rain so could be just left on all the time. That window was facing the sea (a couple of miles inland) but always had a nice fresh breeze so was ideal for ventilation.

That kind of switchable, flexible window fan would be perfect to DIY with a small bracket to hold ducting to it when needed to solder and screening to keep bugs out of the room..

If you are inside a building without window or vent access, a HEPA filter would be super useful. "activated charcoal" s likely called for in a commercial situation to protect people against "colophony disease" but should be separate from the HEPA filter because the charcoal needs to be replaced after x hours of use and thats fairly frequently because activated charcoal wears out -

apparently once it comes out of its plastic package it starts deteriorating it loses efficatiousness from simply being exposed to the air for an extended period of time even if its not used. A filter thats up to this task is guaranteed to be bulky and expensive. It should likely be stored in a closed plastic bag when its not in use if somebody wants to maintain it as effective in sucking up colophony fumes. But in a commercial situation there may even be rules requiring its frequent relacement.

It will absorb cooking fumes and literally everything in the air - not just the "colophony" (resin) which can cause a sort of atopic illness caused by hypersensitivity to solder In a crowded factory, (many of which have likely moved to Asia now) these commercial, high quality systems are needed and need to be maintained as their manufacturers specify..

[artag]

Smoke matches.

https://www.amazon.co.uk/dp/B07F142M1Q