Sorry I haven'thad time to read all the replies, but...... The air flow meter readings are to be taken by a person (LEV (Local Exhaust Ventilation) qualified) who can interpret the readings and apply those reading to the respective tables, thus coming out with a conclusion of ‘ is the fan fit for purpose’?
Size of room, purpose of fan, air change rates per hour etc...
Just putting the air flow meter reader near the fan and writing down X meters persecond is not the answer!!
Is an airflow reading required X meters downthe flue? At the point of exit? Is the flue the correct type? Is it for a bathroom or a COSHH store?
Once again sorry for muddying the waters