Calculating CFM or Velocity from Area

In this video we’ll learn how to calculate the Total CFM in a section of ductwork or moving across a coil or other piece of equipment. Then we’ll learn what happens to velocity when we try to reduce our ductwork without reducing or CFM.
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[@Behuman0627]

Superb video sir, i would like to request if you can please make a same demonstration for round ducts also.
Thanks in advance 💓.

[@MEPAcademy]

Thanks for the suggestion.

[@katuraysalad]

Great video ❤. Very informative

[@MEPAcademy]

Glad it was helpful! Thanks for watching.

[@ncameron7]

Great video!

[@MEPAcademy]

Thank you

[@Aj-cd1in]

Where did the 144 come from

[@MEPAcademy]

There are 144 in2 in a square foot. 12" x 12" = 144 in2

[@michaelmaclachlan2152]

Great video! Thanks!

[@MEPAcademy]

Glad you liked it! Thanks for watching.

[@germanarci8477]

new on ventilation... why wouldn't we always choose the smaller diameter to get the highest velocity on the duct?

[@MEPAcademy]

Higher velocities for the same volume CFM will cause the fan to work harder, causing an increase in energy consumption.

[@jw261989]

Can you help me with this 12 x12 duct 2000CFM what is the FPM ?

[@MEPAcademy]

First you determine the area of the duct, which in your case is 12" x 12" = 144 in2. Then you need to convert this to feet as we're looking for "Feet per Minute). 144 in2 / 144 in2/Ft2 = 1 Ft2. The normal formula is Velocity x Area = CFM, so we just work backwards taking the 2,000 CFM dividing it by the 1 Ft2 = 2,000 FPM of Velocity. To check your self put the values back into the original formula of 2,000 FPM x 1 Ft2 = 2,000 CFM. Hope that helps.

[@miguelh.maci1148]

Can you please help me resolve this question question?An 8x12" register has the velocity of 300 FPM with the free area of 75% what's the quantity of air exiting the register?

[@MEPAcademy]

Gross area would be 8" x 12" = 96 in2 x 75% free area = 72 in2 / 144 in2/ft2 = 0.5 ft2 x 300 FPM = 150 CFM

[@user-xt2jx1fr1z]

szoval a ventilator rpm kell megallapitanom appszolut nem tudom hogy alljak hozza jarmu sebessege 70 ml/h + korulbellul szel sebessege vagy iranya az atmero 120 vagy 127mm 10-12 lapatos turbina ki tud segiteni megkoszonom!

[@MEPAcademy]

Good luck. Thanks for watching.

[@williamsalaam1112]

Where 144 in2 come from?

[@MEPAcademy]

12 inches x 12 inches = 144 in2. This is equivalent to 1 square foot.

[@jeffpeast01]

Where did the 114 number come from?

[@MEPAcademy]

144 is the equivalent square inches in a square foot. 144 Sq. Inches = 1 Sq. Ft

[@RaydieCagas-bq6kb]

how about aircon cfm calculate?

[@MEPAcademy]

For air conditioning ductwork it's the same calculation. CFM in an air conditioning dict is based on the area of the duct and the velocity. CFM = Velocity x Duct Cross Sectional Area

[@munnathakur3375]

👍🏾👍🏾😃

[@MEPAcademy]

Glad you liked it. Thanks.