How to cal speed of fan related to air quantity

Flowrate through any fan is also a function of system resistance. When you look at the path of air from atmosphere to the inlet of the fan, and from the fan discharge back to atmosphere, what is the resistance to air flow along this path (ductwork, louvers, wall openings, etc.)?

The manufacturer of the fan can give you a fan curve or performance chart. For a given fan speed and system resistance, this information will give you the volume flow through the fan.

Thank you very much. I have 5rows fin cooler above this fan as my resistance path. How about Fanning Equation, it has relation between Q and N(speed) ? Can I use it as riughly estimated ?

Nong