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The unit of the flow rate and pressure of Centrifugal fan

- Sep 04, 2018 -

FLOW RATE 

The flow rate is the volume of the air taken in over a certain period of time and it is normally expressed in m3 /s, cfm or m3 /h. 


Qv= v A 3600 

where: 

Qv = Flow rate in m3 /h 

v = Average fluid speed in m/s 

A = Outlet section in m2 


PRESSURE 


The total pressure a fan can generate is the algebraic sum of the static and dynamic pressures and is normally expressed in mmH20 or Pa. 


The static pressure is that portion of the total pressure related to the fluid itself, no matter what its air speed: it is the potential energy that overcomes the resistance exerted by the circuit as the fluid passes through. 


The dynamic pressure is derived from the kinetic effect of the moving fluid and is a function of the speed and density of that fluid. 


Pd= 𝛾 2g v 2  


where: 

Pd = Dynamic pressure in mmH20 

γ = Specific gravity of the fluid 

g = Gravity acceleration (9,81 m/s2 ) 

v = Average fluid speed in m/s