The SPRD is a single-blade, steel barometric damper with a counter-balanced, weighted arm for control of bypass air for zone systems. The SPRD is available in rectangular, square or round styles. An SPRD is used on zone systems when the automatic closing of various zone dampers created an excessive increase in air pressure and velocity throughout the duct system. An SPRD will automatically open as the air pressure in the duct system increases, eliminating excessive system air pressure and associated air and register noise.

Sizing the SPRD is done by subtracting the smallest zone's CFM requirements from the system's total available CFM. When sizing the system, it is recommended that the SPRD be located in a common duct ensuring that whenever system static pressure rises above designed specifications the SPRD will open to relive the system of the excess pressure.

Features

• Counter-balanced weighted arm to control bypass air for zoned systems.
• Air pressure in duct system increases as zone dampers close, pushing the SPRD open automatically.
• Arm and weight both adjustable to control amount of air bypassed.
• Recommended for low pressure systems with less than 0.5 in. wc.
• For larger systems and tighter pressure control, use modulating dampers and static pressure controller (SPC).