corsi-rosenthal boxes

a corsi-rosenthal box is a fairly inexpensive, DIY, highly effective and very quiet air purifier you can make with materials following a single hardware store run. the archetypal corsi rosenthal box is made up of four MERV-13 furnace filters taped up into a box (airflow direction pointing inwards!) with a cardboard bottom and a box fan facing outward (such that it pulls air through the filters) on top. joints should be thoroughly taped such that all air must be pulled through the filters, and not elsewhere.

at the 0.3um particle size, MERV-13 filters have in the ballpark of 84% efficiency. this is much less than HEPA. however, due to their much lower resistance compared to HEPA, much much more air can be pulled through them without an increase in noise. because the air in a room will be filtered continuously, the low first pass efficiency is no matter: the increase in airflow works out such that you actually achieve higher clean air delivery rates than a HEPA filter.

MPR 1900 3m filtrete filters are preferable for this, as many other filters that claim to be MERV-13 actually test below MERV-13, and the MPR 1900 have exceptionally low resistance.

How to make a Corsi-Rosenthal Box (pdf)
How to make a Mini Corsi-Rosenthal Box (pdf)

this is the web mirror of a gemini capsule by the same name.