DIY air sterilizer using electricity

[Felipe Tanaami]

Hi! It's my first publication here. English isn't my native language, so forgive my mistakes...

HEPA filters in my country are very expensive, and the squirrel cage blower used to pump them cost thousands of $ (equivalently).

So I made a few searches, and I found this:

https://www.youtube.com/watch?v=x5YFK8mmeRQ

http://www.instructables.com/id/How-to-Make-a-Negative-Ion-air-ionizer/

http://www.engineeringtoolbox.com/particle-sizes-d_934.html

Anyone has thoughts on this?  I was thinking doing several aluminum foil covered rectangular plates, spaced 1.5 cm (need to make some calculations on this, to not make a accidental discharge). They are positively/negatively alternated (I think this will have a better performance). That capacitors bank can handle something this big? I was making a cardboard prototype, but luckily, I read somewhere that both cardboard and wood are good conductor of high voltage.

Any help will be appreciated! Good day!

[Jake]

Building a flow hood isn't that difficult or expensive if you can source some of the materials cheaply.  I built one using a furnace blower, some polyfill, and standard MegaMart HEPA filters.

The furnace blower I got for free.  It's a bit overkill size wise, but works fine for the size hood I built.  You can try calling local HVAC places in your area, they will usually have blowers that they're just going to scrap.  I grabbed my phone book and started out ready to call every place until I found one, and got lucky on the first try.

You need easy to sterilize surfaces.  Laminate works well for this and you don't have to overbuild doing it this way.  That was one mistake I made.  I used 3/4" laminated particle board for mine, and it takes 2-3 strong people to lift it.  Woodshops, cabinet makers, and kitchen-type construction/remodeling places will often have scraps of laminate that are plenty big.

For the HEPA filters... many of the cheap types will be unsuitable because they have blow-by.  Some you can fix with hot glue or caulk, but look for ones that don't have obvious gaps around the edges.

Just using a HEPA to blow air around is usually counter-productive.  You really need still air and a bunsen burner.  Any drafts or disruption in the air will increase your contamination rate.

You might consider using UV in your lab.  You can get UV tubes that fit in standard fixtures.  Here's the ones I use...

https://www.1000bulbs.com/product/1931/AU-LG30T8.html

They're around $12 each and will fit in a normal light fixture of the correct wattage.  You don't need a special ballast even though they do sell them.  Do NOT expose yourself to this light for any longer than the few secs. it takes to turn them off when you enter the lab, and obviously don't look at them when on without eye protection.  They will give you a NASTY sunburn that is NOT the pleasant warm feeling and nice tan you might get from an hour in the sun.