Specifying Smoking System-Pressure Drop

[RJB32482]

I am trying to calculate how much volume our industrial smoke generator (for pipe leaks) will produce from their data. They say that it will produce 8761 CFM at 3.0" of static pressure (I assume inches of H2O). Is calculating this just like a pumping system which would follow:

1. Find velocity by dividing vol. flow/area of piping
2. Calculate pressure drop throughout the piping system.
3. If more than 3.0" flow will be less, less than 3" flow will be greater.

Is this a correct calculation?

Thanks