Evaluating Firestops as a Smoke Seal

Abstract

A through-penetration firestop assembly is a specific construction consisting of the materials that fill the opening through the wall or floor to maintain the integrity of fire-resistive walls and floors by preventing spread of fire. Because of the concern over non-thermal damage and life-safety issues related to smoke in building fires, renewed attention is being given to the firestops as a potential smoke-seal instrument. Evaluating the current L-ratings to field applications has been investigated through two sets of tests, cold and hot, with four sets of firestop assemblies of different L-rating values. Each assembly was placed on top of an ASTM E-814 furnace and covered by a smoke collection box. In Cold Tests, the amount of smoke penetration through an assembly from a small polyethylene pan fire inside the furnace was measured. In Hot Tests, the assemblies were exposed to temperatures similar to those in the ASTM E-814 test and the amount of smoke collected in the box was measured. The amount of smoke that penetrated through an assembly in the Cold Tests correlated reasonably well not with the L-rating but with the estimated k-factor of each firestop assembly. The amount of smoke measured in each Hot Test, which was mostly from the decomposed penetrating item (e.g., cables) and its accompanying stuffing materials, was orders of magnitude greater than that in the corresponding Cold Test, and established no correlation with the estimated k-factor of the corresponding assembly. Two recommendations are made: (1). Instead of issuing a L-rating, which does not reflect the true capability as a smoke-seal, issuing a k-factor for each firestop assembly through a test similar to the current L-rating test, and (2) Issuing a new rating based on the total amount of smoke generated while a firestop assembly goes through a F-rating test.