| [* black] NMB Technlogies BM5115-04W-B50-L00 blower fan with 3.5 CFM (0.098m³/min), but higher static pressure of 0.803 in H2O (200.0 Pa) provides ample airflow with a single air intake filter and two expiratory flutter valves. https://www.digikey.com/product-detail/en/nmb-technologies-corporation/BM5115-04W-B50-L00/P15682-ND now limited in supply. |
| [* icon_note] Max CFM rating might seem too high, but remember that is ''without'' back pressure. With resistance of filter and flutter valves, actual flow rate is much lower, about 20 l/min. |
| [* black] http://d.digikey.com/HS000xU3ppttIK40NAX00T7 Delta BFB0512HHA-CZMQ has also tested well. It is slightly lower flow, but much quieter. I have worn this while working in the OR for 11 hours. My EtCO2 at 2 hours was 40 with this Delta fan. Its mounting holes must be slightly enlarged to fit 3 mm bolts. |
| [* icon_caution] PLEASE DO NOT HORDE FANS. Only obtain the number you will actually ''deploy'' to providers. Hording deprives others in need during this COVID-19 crisis. |
| [* black] Other blower fans may yield more ideal combination of power draw, static pressure, flow rate, noise, and availability. 200 to 250 Pa static pressure capability is likely best range. |
| [* black] If you change fan model, always verify CO2 levels via gas sampling
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