ASSESSMENT OF THE FIRE RESISTANCE LIMIT OF AIR DUCTS IN SMOKE CONTROL VENTILATION SYSTEMS

This study considers the assessment of the fire resistance rating of air ducts insmoke control ventilation systems as a significant factor in ensuring fire safety. It demonstrates the importance of the E and I criteria, as well as requirements for material non-combustibility, flange joint tightness, and duct wall thickness. The paper describes combined fire-protective and thermal-insulating coatings based on basalt materials that provide EI30–EI240 ratings when correctly installed. The control methodology includes visual and instrumental measurements of coating thicknesses, wall thicknesses, and protection of fastening elements within supervisory practice. The results of field inspections and a survey of 20 experts, with high agreement per Kendall (W = 0.82), identified three most critical non-compliances: nonconformance of duct wall thickness to design values, insufficient installed thickness of fire-protective coatings relative to regulations, and improper protection of fastening elements. These defects lead to reductions in E and I ratings, risks of deformation, loss of tightness, and deterioration of aerodynamic characteristics, directly threatening the effectiveness of smoke extraction and evacuation conditions. Recommendations include strengthening incoming quality control, strict adherence to technological regulations, the use of certified non-combustible materials, and improving practitioner awareness. Implementing these measures ensures attainment  of the required EI classes and the issuance of a certificate of compliance for commissioning.