The system has a redundant inlet of supply air with a pack (10), where a valve is arranged in the inlet for airflow regulation. An electric flow rate regulating valve (EFCV) and a pneumatic flow rate regulating valve (PBV) are arranged before the pack in a parallel connection for airflow regulation. The air flow for supplying the pack is regulated exclusively by the EFCV. The flow is adjustable by the PBV if the EFCV fails. The rate is continuously measurable by the EFCV over pressure measurements in a venturi nozzle (20).
