Design 0540V Broad Frame Static Curtain Fireplace Damper is UL approved to be used where making codes call for the security of HVAC ductwork penetrations in vertical hearth separations (walls or partitions) that have a fire resistant ranking of 4 hours or a lot less. The 0540 is assessed for https://dampers-for-industrial-se91123.mdkblog.com/42831782/the-2-minute-rule-for-dampers-for-industrial-sector