Grease duct joints are held jointly by the use of shaped V clamps and sealed with 3M Fire Barrier 2000+. Reduction in cross-area: The internal Proportions (width and height for rectangular ducts, diameter for round ducts) on the smoke extracting ductwork shall not reduce by in excess of 10% throughout https://fire-resisting-ductwork-i23455.newsbloger.com/37618271/the-smart-trick-of-fire-resisting-ductwork-insulation-that-no-one-is-discussing