Article 2, Definition (4) states that the maximum flowrate is related to the airflow at the lowest achievable total pressure difference, to be chosen from the following set of values: 10 (minimum), 20, 50, 100, 150, 200 or 250 Pa, whichever is equal to or just below the measured pressure difference value.
In the case that a non-ducted RVU cannot deliver 10 Pa, the maximum flowrate is determined at the actual pressure and, according to the Regulation, the minimum pressure is declared to be ‘10 Pa’ instead of the actual pressure (as in EN 13141-4 Section 3.5).
Disclaimer: Please note that the European Commission cannot provide a legally binding interpretation of the EU legislation, as this is the sole competence of the European Court of Justice. Any remarks from the European Commission services are without prejudice to the position the Commission might take should related cases arise in a procedure before the Court of Justice.