Nailor Design 0722 Ceiling Dampers are for use in spherical applications, in lieu of hinged door sort dampers in any UL/ULC ground/ceiling or roof/ceiling assembly with as many as a 3 hour fire resistance rating exactly where air ducts are allowed. Model 1221G is actually a large effectiveness combination hearth/smoke damper specially suitable for https://dampersforindustrialsecto68890.theobloggers.com/43360939/heavy-duty-stainless-steel-damper-manufacturers-fundamentals-explained