Manual

butterfly-damper

http://airporttourandtravel.com/ways-to-succeed-in-college-3/

Butterfly Dampers

here Butterfly Dampers, or Butterfly Backdraft Dampers, can be built to customer specifications are ideal for shut off and backdraft prevention applications when system is not in use. Air Systems has created butterfly backdraft shut off dampers for a variety of customers to satisfy their unique criteria. Seal designs include: Swing-Through, Tadpole, and Step-Seat.