20X8 ND-HD | 20X8 ND-HD HAND DAMPER | EWC Controls

20X8 ND-HD HAND DAMPER

The ND-HD Series of rectangular Hand Dampers are designed for field adjustment of Differential Pressure and Volume Control on Rectangular or Square Bypass Air Duct Runs. Pursuant to ACCA® Manual Zr, “A balancing hand damper should be installed in the bypass duct” for setting adequate resistance to bypass flow. The ND-HD includes a Heavy Duty Manual Quadrant allowing Easy & Accurate Field Adjustment of the Pressure Drop through the Bypass duct run. In addition, the ND-HD has a factory installed Stop Bolt resulting in 70% maximum closure. This superior design ensures minimum bypass flow even if the hand damper is accidentally closed. Airflow can be from either direction and the Damper can be oriented in any position. The ND-HD is designed to provide reliable and quiet Balancing & Volume control functions at velocities up to 2500 feet per minute. ND-HD dampers are easy to install and adjust. The superior design insures long life with no maintenance and a 5 year warranty. See Application Note #090376A0169C for installation and setup instructions.