ALSIDENT¨ SYSTEM 10 Airflow Alarm. The ALSIDENT¨ SYSTEM Airflow Alarm mounted directly on the extraction arm gives security for optimal airflow through the extraction arm and not only security for operation of the ventilation system. The Airflow Alarm is a vacuum based measuring instrument securing that sources of error such as a closed damper, foreign substances or accumulation of substances do not reduce the efficiency of each extraction arm during operation.