Obstructions and Early Suppression Fast Response Sprinklers

Early Suppression Fast Response (ESFR) sprinklers were developed to meet the demands of high challenge storage fires and are commonly used for warehouse fire protection. Obstructions created by ceiling structural members, lighting, or piping, can hinder ESFR sprinkler performance. Unfortunately, ESFR sprinkler obstruction sensitivity was largely unknown. Acknowledging the importance of this issue, in 2014 a multi-year testing program was initiated. The fourth and final phase of the project was completed in September of 2019. In total, 65 Actual Delivered Density tests and nine full-scale fire tests were completed using K240 and K200 (K17 and K14) ESFR sprinklers. The results of the testing showed that the obstruction created by an open web steel truss 0.56 m to 0.91 m (22 in. to 36 in.) in depth, located a minimum of 150 mm (6 in.) horizontally from an ESFR sprinkler, will not significantly decrease sprinkler performance. The obstruction created by a bridging member or other obstruction 38 mm × 38 mm (1.5 in × 1.5 in.) in size or less, located a minimum of 0.30 m (12 in.) directly below an ESFR sprinkler, will not significantly decrease sprinkler performance. This also applies to a bridging member attached to open web steel truss. The obstruction created by a flat or round obstruction less than or equal to 0.30 m (12 in.) in width, located a minimum of 0.15 m (6 in.) horizontally from an ESFR sprinkler, will not significantly decrease sprinkler performance. The findings of this project were used as the basis for revisions to the 2022 edition of NFPA 13.