Non Return Damper's specifications:Frame is constructed from galvanized steel sheet. Welded joints are protected by aluminium spray coating.Air operated damper blades are fixed to the frame by self oiling nylon bushes with 8 mm dia aluminium pipes.Blades are sealed with foam gasket at the bottom to avoid rattling noise and to provide air tight operation.Blades open full or to any angle depending on the air velocity. Blades stay in position of opening without fluctuating when there is constant air flow. Blades closes quietly when the air flow stops.Designed to maintain a constant pressure level inside pressurized rooms. Used at duct outlets to prevent back draft when air moving devices are switched off.In a multi fan installation non return dampers prevent back draft through the operating fans.Structure is available with flanged edges and are supplied un drilled as standard.Available in square and rectangular sizes.

• Superior finish