Thread by @RogueVictorian

I promised I would provide a way to calculate room air exchange, using a simple MERV-13 filter & a box fan. The sweet spot seems to be 6 exchanges per hour. This means all the air in the room is moved through the filter 6 times in 1 hour. 1/6 #ProtectHCWs #ProtectKids #Covid #BA2

First we need to get the volume of a room. It doesn’t need to be perfect! But note units are important. We are using feet/inches here. Use this calculator & input the measurements, A, B, & C as shown in the graphic below. Order is NOT important 2/6 #Filter vcalc.com/wiki/KurtHeckm…

I found a company that did calculations using a box fan on high speed & MERV-13 filters of different depths. The thicker the filter the BETTER the air flow! Strange but true. Note I added the Air Volume based on a 20” square box fan. 3/6 #N95 #BoxFanFilter texairfilters.com/how-a-merv-13-…

Now we will take your room volume you calculated. Multiple it by 6, or the number of times you want to exchange the air per hour. That is the amount of air you need your fan to filter per hour. If that number is less than than the above numbers, you are covered! 4/6 #LongCovid

What do I do if my calculated number from above is greater than the calculated filtration rates??? You take the number from above & divide it by whatever your fans CFH number (based on filter thickness). Round to the next largest whole #️⃣. 5/6 #ventilation #ProtectTeachers

Here is a graphic showing how the set up works. I have a tweet with instructions for making one too! Disclaimer: this is not HEPA filtration, it will DECREASE the viral load in the air this decreasing risk of infection. You NEED to wear an #N95Mask to be fully protected. 6/6