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How to calculate pressure thrust created by a fan?

  1. Jun 10, 2012 #1
    If I know fan specifications like the size, CFM etc. How can I calculate the pressure thrust or negative pressure it creates.

    I am using a fan in an opening of the cabinet that pushes air outside the cabinet. And I need to know how much pressure drop it will cause on the suction side. It will be very small I guess but worth calculating.
  2. jcsd
  3. Jun 10, 2012 #2
    It is easier to measure. If you do not have a manometer, make a U-form one (transparent pipe may suit it) filled with water. Difference in water levels will show the vacuum in the box in mm of water column the fan can achieve.
  4. Jun 10, 2012 #3


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    Staff: Mentor

    [static] Pressure is typically part of the specs, but if all you have is CFM, then the static pressure is probably near zero. So just use geometry to convert cfm into fpm, then use bernoulli's equation to convert velocity into velocity pressure, then geometry again to convert velocity pressure into force.
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