Backdraft dampers: Mounted to permit just one-way airflow, these styles incorporate shafts on one finish of every blade to avoid air from flowing again in the alternative way. If important, a counterbalance can help. Circular airflow management damper for a wide variety of standard VAV purposes. Brief and easy commissioning. https://aircontroldampersforengin57789.rimmablog.com/35596419/air-control-dampers-for-engine-sheds-fundamentals-explained