The airflow is inwards as the air turbulence is greater with the blades pushing into the initial poly-cotton filter so more friction, more static. Also the layers of washable filters dampen the fan noises a fair bit. I have two units on either side of the building, whichever side has the higher external air pressure is active, using natural air pressure the fans need to do very little work. As apartments here happen to have two pre-built natural gas safety vents should you use gas, it was simple. Current I never measured but its all 12v, the laptop psu running them barely feels warm at full load so a lot less current than a charging laptop. Part of the reason for the 12v is I use induction coils from a car to add additional charge because the washable fiber filters are less efficient than the normal disposable filters. I just happen to have replaced over-plug individual coils from a Renault so the old ones were still mostly OK. Obviously ozone is to be avoided but decent distancing of the charge plates and not a problem. In the US though disposable big furnace filters are easy to get, nobody has heating here
Forgive all the questions, I've dabbled in electronics. So the fans have a hepa filter on one side, and a washable filter on the other? The fan motors are running on DC, not AC? How do you determine which side of the building has greatest external air pressure? And what type of motor controller/logic are you using to control these two fans together, using external air pressure as in input? What are you using to determine the air quality? So, air quality input goes to its own motor controller? And not to the controller that receives air pressure inputs?
No worry, nice break from telling the idiots they are idiots, someone has to do it but every day? Haha. The picture is of an older portable unit with furnace filters (both sides). The large scale apartment filters are bigger (2m high) but fairly discrete looking. The filters are all washable but filter to better than the merv13 I was ordering in ( they weigh little but are big you pay a fortune on airfreight and use two a week). When it got to 5x filters 50 bucks, shipping 350 I figured new plan). The mixture of polyester, polyurethane, cotton I have with large surface are let's through no pm 2.5 or 1.0 and and under 300 0.3um per cubic meter. The fans are all large PC or server blower fans I had, 12v DV, fairly quiet and push a lot of air.. Axial fans move air well but don't perform when there is air resistance so a blower is superior. The rest is all Rasberry Pii controls. I used a car MAP sensor to read air pressure. WiFi connects them but there is a hinge flap as well as when run in reverse the fans do generate some power, I noticed the led was coming on my first variable speed controller.. Did not seem to cause issues but better to be safe with the Rasberry boards I did not program the Raspberry Piis, ten years back maybe but my developer has a ton of experience with medical devices so it would have been a ridiculous waste of time for me. There are loads of projects for Pii and Arduino with particle detector add ons. I had initially planned to use an analog system. I have had quite a bit of experience MacGyvering stuff on my world travels, made a few hydrogenerators etc. I rigged a fridge freezer to run directly off a paddle wheel in the river once.
lol you'd have made a fine engineer. I was gonna rig a little solar setup to run a fridge and a few other little items but then I saw Tsing Tao say he had a natural gas whole house generator and that sounds pretty clever. I previously dismissed generators because I don't want to have to store 20 gallons of gasoline which these days doesn't store well and requires additives etc. If the 'hood was torn up enough to wreck gas lines there probably wouldn't be much left anyway. Definitely gonna look into this. Masks though... My N95 started smelling like balls so I have to buy a new one today. Thinking of maybe just going paper but I'm a little uneasy. At least N95 is probably doing something but I notice everyone else is using paper around here.
Natural gas generator is the way to go. Generac. They've come a long way recently and they're really quite good. Once a month I run it for 5 min. It runs the AC units, the fridge and a little spare for some lights. That's all we need here in FL.
NG generators are the way to go. I had one installed at my old home a couple years ago. Cost was 5K for a whole house generator which ran everything in my 2300sq. ft. home if the power went out. Biggest draw on amps is the A/C by far, followed by sump pumps, refrigerators and furnace. Lights are nothing. I highly recommend getting one. Electric can go out anytime for many reasons. If the NG goes offline it's probably MadMax time.
I grew up with my dad who had both mechanical and electrical engineering degrees, he designed powerstations and I spent my childhood holding tools for him My N95s I leave in a sunny window and that seems to cook the bugs out. My sister in laws place rarely gets sun so I have her a little peroxide and very small perfume atomiser. You just need a puff and leave for 20 minutes. It seems to do nothing bad to the glues or plastics. I use solar (copper under glass) to heat motor oil which in turn dries a liquid dessicent that cools my place. It could run of gas as well. Again, trading there are big gaps you need direction with so little ideas to impliment are good.
Wearing a mask is not effective at all. A virus can't kill a person in the first place. Anyone with any knowledge about what a virus can do or can not do knows that. Duh.