How to calculate pressure thrust created by a fan?

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To calculate the pressure thrust created by a fan, knowing specifications like size and CFM is essential. For a fan pushing air outside a cabinet, measuring the pressure drop on the suction side can be done using a U-shaped manometer filled with water to determine the vacuum in mm of water column. If static pressure data is unavailable, it is often close to zero when only CFM is provided. The calculation involves converting CFM to feet per minute (fpm) using geometry, applying Bernoulli's equation to find velocity pressure, and then converting that to force. Accurate measurements and calculations are crucial for understanding the fan's performance in the given application.
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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.
 
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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.
 
[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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