@@ -26,6 +26,8 @@ While it is tempting to simply bolt a blower onto our [Covid Isolation Box](http
In order to scavenge hazardous vapors, fume hoods need laminar flow and adequate velocity; the aforementioned sticker reminds users that raising the sash above a marked point disrupts airflow enough to prevent the system from functioning properly. Similarly, we must understand the airflow in our system and design the exhaust mechanism accordingly if we want it to protect caregivers. As such, we are starting with simulation using Dassault's [Simulia platform](https://www.3ds.com/products-services/simulia), building on their work simulating sneezing, coughing, and breathing for our mask and face shield design efforts. The simulation results will feed into [blower sizing and selection](https://www.digikey.com/short/zpvw1d), at which point we will build our first physical prototype.
Due to the inherent uncertainty in sealing around the perimeter of the box, it is likely that we will need to implement some kind of active blower control to maintain sufficient aerosol scavenging. Since the exhaust will pass through a safety-critical filter, we should also monitor filter performance online and alert caregivers when replacement is needed. In both cases, we will likely instrument the box with low-cost PCB-mounted differential pressure sensors such as [these models](https://www.amphenol-sensors.com/en/novasensor/pressure-sensors/3161-npa-series) from Amphenol (~$30 each single-lot from Digi-Key and in stock). Again, simulation results should point us to the needed pressure differential range we need to maintain to produce good flow conditions, eliminating the need for airflow sensors.
