// HACKER NEWS — CYBERSECURITY
Initial DIY Cleanroom Experimentation
I decided to try a simpler version, testing how much I could
positively pressurize a single room with a relatively powerful HEPA
air purifier (AirFanta
3Pro. This is close to a best case, since most people won't have
something as good as an AirFanta.
My first question was whether the AirFanta can pressurize much of
anything, since it uses axial fans and these can stall when facing
excessive pressure:
To measure the pressure delta I was going to need some kind of
manometer. Most cheap test tools are designed for very large pressure
differentials, but I found the Testo 510i which looked
to be just barely good enough with its 5 Pa rated accuracy.
I taped a trash bag around the top of the AirFanta and measured what
pressure it could get to:
There were some small gaps in the taping, but it got to 83 Pa. Pretty
good!
Then I tried pressurizing a room. Someone in a tight modern house
could probably get close to that 83 Pa, but ours is old and leaky so I
wasn't expecting anything in that range. I opened the bag the rest of
the way at the top, taped it across the door, and used plastic
sheeting to close off the rest of the doorway:
It billowed out, and I felt air escaping through the many tiny gaps in
my taping. I forgot to take a bias measurement first to calibrate,
though, so I don't have a pressure number for this setup.
The issue with putting something over the door is that every time you
go in and out of the room you need to carefully seal and unseal it.
Which uses a ton of tape! Unless your room has two doors, you'll
quickly run out of tape. Clearly we should go through a wall.
I made a 13x13" hole in my wall [1], and mounted the AirFanta
horizontally. It immediately fell apart, because it uses friction
fits that aren't designed for sideways loading. I reassembled it, and
used baling wire to keep it together:
I taped around the edges to prevent air from escaping: