Single Blade Dampers
http://adbands.com/products/ad-bands/entertainment?id=14 Single Blade Dampers can be built to fit any shape or size air system and are ideal for low leakage and shut off applications. They are a cost-effective solution for in-duct shut off applications and ideal for paint laden airstreams and low leakage (moderate to high temperature) applications.
go 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.
Variable Inlet Vane (IVD and VIV)
Inlet Vane Dampers, Variable Inlet Vane, and Inlet Box Dampers are ideal for volume control applications. They turn a big fan into a little fan and will provide a 4 to 1 turn down while holding peak static pressure on a fan curve. We’ve built them for spray booths for automotive paint finishing, blow off systems, and fan inlet discharge.