You need the fan manufacturer's characteristic curves or the performance tables.

Or, you can set up a test rig and measure the fan's performance (airflow -v- pressure etc) at varying speeds.

Best get the fan's nameplate details and ask the manufacturer for performance tables.

Michael Reid. ■

There are plenty of articles trying to explain calculation methods scattered all over the internet.

They require input concerning fan speed, diameters and blade orientation etc.

Once you have decided the fan parameters you can use the appropriate formulae to reach your airflow.

You almost suggest some familiarity with the Fan Laws and I recommend you select a 'high pressure' fan and take it from there.

There are many ventilation specialists out there and, as always, some know what they are doing and the predominating remainder try to confuse with jargon and plentiful use of square root signs.

Just read a few better articles and you will get the gist of it. ■