filtration 101 (abbrev):
self-contained filtering of gases and liquids consist of exactly two components. 1) a pump. 2) a filter. it is exactly that simple. pumps are pumps. in gases we typically use axial fans or centrifugal blowers/turbines. in liquids, we do exactly the same thing but with more torque
). filters come in exactly two varieties: chemical and mechanical.
an example of a mechanical filter is a paper HEPA filter. HEPA N is a standard that says that a filter media (the paper), when put in some exact laboratory situation with a blower, will act as a particle diameter low pass filter with efficiency N. that is, at least N percent of the low-diameter particles will stop at the filter, the rest can go through. this is measured over some period of time in an airtight chamber, with a specification blower, i believe, but feel free to correct me on that.
hence, mechanical filters physical block particulates above a certain effective diameter with a certain efficiency.
note that there is no standardized testing committee that certifies hepa filters THAT I KNOW OF. i imagine there is some authorized set of ISO testers. i don't really know and don't own a factory so i don't care.
a chemical filter is a medium which _neutralizes_ airborne chemical compounds via some kind of reaction (hereafter rx). the rx is open, the bandwidth of compounds is open, and the meaning of neutralize is open. i am not familiar with any standards that apply to this action.
however, typically, the kinds of things that people worry about (that are bad for one's lungs to breathe) are organic compounds, because our lungs aren't very good at dealing with those for reasons i don't particularly care to understand (probably because we're made of carbon so they stick to our little oxygen absorber thingamajigs). by definition, an organic compound which can be vaporized and become airborne is called a volatile organic compound (VOC). recall that organic compounds are all compounds that contain the element carbon. hence, what we are worried about is airborne contaminants which have carbon somewhere in their chemical construction. hence, we've come up with a fantastic way to neutralize them. we produce more carbon, negatively charge it, and give it lots of surface area, and then pass the air over it. ta-da! some poor charcoal has taken the blow and had to become attached to this nasty compound instead of our lungs. NEUTRALIZED *****. there is a standard for this, because it's actually incredibly effective, and there are tons of organic compounds which are very nasty carcinogens. also lung cancer ****ing sucks, it grows quickly and kills you in the most painful possible way.
another type of chemical filter is a silver mesh. for reasons i can't remember at all, silver does nasty things to cell walls, so if you're a small enough airborn micro-organism and your cell wall is of a garden variety (tuberculosis and many other microorgs have weird hardened cell membranes), contact with the silver might kill you. again, no standardized testing really.
SOLDER FUMES:
are all fumes from the flux burning. the metal in the solder is very heavy and we don't solder at high enough temperatures to vaporize it (like 900K). rosin flux burns to a remarkably harmless compound which i can't remember at all, but is picked up most effectively by a chemical filter. hence, i'm going out now to buy 40lbs of ionized charcoal pellets. BYE EVERYONE!
