Frequently Asked Questions...

Q. Why is background ventilator performance still in mm²?

 A. Confusingly the unit of measurement used in the draft document is still mm², even though this equivalent area figure is arrived at via an air flow performance rate. The existing Part F depicts products in units of mm² but this is used in reference to the geometric opening of the ventilator. We would encourage mm² to always be suffixed with 'equivalent area' or 'free area' to differentiate in future.

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