Art Rectangular Silencer™ silencers provide effective and predictable noise control for HVAC and industrial applications. Standard silencers have been tested in a NVLAP® certified acoustical laboratory. All performance data was obtained in accordance with the latest ASTM E-477 standards. This data allows for accurate and reliable selection of the Art Silencer™ for the specified noise reduction requirements. Each Art Silencer™ is configured with optimal design features shape, geometry, fill materials, frequency loss, and velocity classification, and options to meet performance needs. There are models to handle airflow velocities from 0 to 10,000 fpm Materials of construction for all standard silencers include 22-gauge, galvanized steel outer casings, 24-gauge, perforated galvanized steel inner baffles, and an acoustical fill that has been tested in accordance with UL 723 procedures and meets NFPA 90A requirements