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[title] Fans Tested
[* black] Typical, small tubaxial fans lack sufficient static pressure capability for use in the Fan HALO configuration. We are drawing air in ''through'' a viral filter. Static pressure capability is vital, but we must also balance against filter flow limits.
[* black] Blower style fan yields much better performance than tubaxials. I use this 51 mm blower from https://www.digikey.com/product-detail/en/nmb-technologies-corporation/BM5115-04W-B50-L00/P15682-ND
[*
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 and pressure 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.
[* black] Blower style fan yields much better performance than tubaxials. I use this 51 mm blower from https://www.digikey.com/product-detail/en/nmb-technologies-corporation/BM5115-04W-B50-L00/P15682-ND
[*
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 and pressure 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. 150200 to 250 Pa static pressure capability is likely best range. Fans in the upper end of range may require change to a single flutter valve to control flow rate.
[* black] These alternative fans are good candidates, but I have not yet tested them. If you change fan model, always verify CO2 levels via gas sampling
[* icon_note] https://www.digikey.com/product-detail/en/sunon-fans/MF50151VX-B00U-A99/259-1829-ND/7691033 https://www.digikey.com/product-detail/en/sanyo-denki-america-inc/109BC12GC7-1/1688-1035-ND/6191751 https://www.digikey.com/product-detail/en/cui-devices/CBM-5020V-148/102-5585-ND/7623146
[* black] Other blower fans may yield more ideal combination of power draw, static pressure, flow rate, noise, and availability. 150200 to 250 Pa static pressure capability is likely best range. Fans in the upper end of range may require change to a single flutter valve to control flow rate.
[* black] These alternative fans are good candidates, but I have not yet tested them. If you change fan model, always verify CO2 levels via gas sampling
[* icon_note] https://www.digikey.com/product-detail/en/sunon-fans/MF50151VX-B00U-A99/259-1829-ND/7691033 https://www.digikey.com/product-detail/en/sanyo-denki-america-inc/109BC12GC7-1/1688-1035-ND/6191751 https://www.digikey.com/product-detail/en/cui-devices/CBM-5020V-148/102-5585-ND/7623146

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