Evaluation of Fire Resistance of Firestop Systems for Floor-Drain-Sleeve Penetrations Based on Geometric Configuration

This study quantitatively analyzed the impact of geometric configuration of floor-drain sleeves penetrating floor slabs on the thermal insulation performance of firestop systems. Eleven square and round sleeve types were tested, with the lower-sleeve length and upper-opening area as key variables. Using identical firestop material, temperatures were measured at specific points within each sleeve. The results showed that temperatures at the water seal and trench center typically remained below 100 °C. However, in a square sleeve (with a 30 mm lower sleeve and 22,500 mm2 opening), the trench center reached 254.9 °C due to heat concentration. As the lower-sleeve length increased from 30 mm to 60 mm, internal temperatures notably decreased—a trend that exhibited a strong statistical relationship, explaining 93% of the thermal variance (R2 = 0.93). While larger upper openings also tended to reduce temperatures, the correlation was weaker (R2 = 0.42). High-temperature responses were predominantly observed in square sleeves, which were also dimensionally less favorable—highlighting the need to distinguish geometric effects from size disadvantages. This study empirically demonstrated that sleeve geometry significantly affects fire resistance performance and provides foundational data for advancing performance-based firestop certification and developing geometry-informed analytical frameworks.