SCHOFIELD, Wis. — Greenheck’s HBT-221 rectangular bubble-tight damper is now available in larger sizes up to 48 by 52 inches in a single section. This allows larger openings to be filled with one pre-engineered damper to provide zero leakage rather than a multi-section assembly that can add a significant amount of pressure to the system. In addition, larger-size HBT-221 dampers can be configured with a single actuator versus two actuators found in a multi-section damper assembly.

Heavy-duty model HBT-221 features a blade seal mechanically fastened to the blade that is field replaceable and a flanged damper frame for easy mounting. The HBT-221 is available with a full range of electric, pneumatic, or manual actuator options. Each damper unit is factory-tested to ensure bubble-tight leakage performance per AMCA 500-D up to 10 in. wg (2.5 kPa) prior to shipping and meets ASME AG-1, Class 0A requirements. Designed for isolation or decontamination applications where leakage is critical, the HBT-221 damper is ideal for medical facilities, universities, test laboratories, and food processing. For more information, visit