Thread by @Read4Ks

🧵 I made another #corsirosenthalbox air cleaner today for my wife's HS classroom. Our city is on fire with infections today, so I wanted to take the opportunity to show others how EASY it is to assemble something that can 🛑 COVID transmission in a classroom or home. 1/n

All of the supplies can be found at Lowe's for $85. I upgraded the filters to MERV 14 (3M Filtrete 2500), so that added another $25. Four filters, a 20” box fan, roll of duct tape, and a sharp utility knife is all that's required. Here I have cut the top & bottom off the box. 2/n

Next start standing up your filters, use a small piece of tape to hold them together while you get it figured out. Each side will be 21” long. Make a cube. The filters are directional, & have an arrow on the sides to indicate airflow. 🚩Make certain all ➡️ point in to center. 3/n

Next set your cube on the cardboard top you earlier cut off. Line it up, then trace around cube to show where cardboard needs to be trimmed off. 4/n

Start taping the now trimmed piece of cardboard to your cube. Use plenty of tape so that there are no air leaks around edges. I go overboard and double up with the tape. In the second pic you can see plenty of tape is added to corners, and all along edges. 5/n

Inside the cube I add a bit of tape to further adhere the cube to the cardboard. This is optional, but I love tape. (The yellow pucks are Bluetooth indicators that will tell you if filters are getting clogged up.) 6/n

Now set your fan on top of the cube. 🚩Make certain that the fan is blowing out (up) and not down and into the cube. Pro tip: try to get electrical cord to exit at the corner because it makes taping a lot easier. Again, all sins are covered with tape. 7/n

Here is a corner of the cube meeting up with the fan. Sealed tight with lots of tape (theme). 8/n

Time for the aerodynamic shroud. Take the other piece of cardboard you cut off the fan box and tape it to the top of the fan using scotch tape (easy to remove). Trace around fan on cardboard to show what needs to be trimmed. On 2nd pic you can see tracing outline. 9/n

Now is the time to change out that razor blade, because it will make the rest of this so much easier. Trace out a 15 ¾” diameter circle in center of cardboard. I'm cheating here because I have a template I'm laying on top to trace around. Some people use a salad bowl. 10/n

I cut small pieces of tape and overlay them around the cut out (optional). Idea is that this limits any wear and tear on edge of cardboard from fan continuously blowing on it. Next tape it down onto the fan like a maniac. 11/n

On my fan the control knob is on top of the fan, so using that sharp new blade I trim a nice hole and then tape edges down. 12/n

Here is the finished product, took about an hour to build. Testing by @CorsIAQ , @DavidElfstrom , @JimRosenthal4 and others show this $100 air cleaner will work better than a $1,000 commercial HEPA system on removing infectious aerosols from room air. 13/n

Each box system will process between 500-600 cubic feet of air every minute. So the 11,000 cubic feet of classroom will be filtered about every 6-7 minutes, or 8-10 Air Changes per Hour (ACH). 95% of the room air is fully rotated after three times of cycling (18-21 minutes). 14/n

These filters, plus N95 masking should reduce overall virus exposure by 90%. Last line of defense is being boosted. Let me know if you have questions on how to build yours. 15/end
cleanaircrew.org
#corsirosenthalbox #IAQ

Quick reminder why this is worth the effort.
***CDC: children 2.5 times more likely to be diagnosed with diabetes after covid.***

https://twitter.com/CDCgov/status/1479528331825582081?t=wvk8IkJasnNgW2N1CLgKOg&s=19

Here are the three filters out in the wild. Ideally these would be in the center of the room, or at least 3 feet from a wall, but life isn't perfect. With the three fans running on medium the noise level is about 53 decibels for the 1,100 square foot room.

Thread with receipts to show empirically how efficient these #corsirosenthalbox units are at removing aerosols. @ARISense_AQ

https://twitter.com/ARISense_AQ/status/1475950912678072338?t=9hGgddyfZiPU5xay-6Tt2A&s=19