Sprinkler protection of non-storage occupancies with high ceiling clearance

Five large-scale fire tests were conducted to investigate the effects of ceiling clearance, sprinkler type and sprinkler discharge rate on sprinkler fire control performance of a non-storage high-ceiling-clearance scenario. The fire scenario selected for this study is to simulate fire loads of either sale booths or exhibition booths in non-storage occupancies under a high ceiling. Three ceiling heights were employed: 12, 16 and 18 m. Two Large Orifice (LO) sprinklers, an Extra Large Orifice (ELO) sprinkler and a K363 Control Mode Specific Application (CMSA) sprinkler were used. All the sprinklers tested are pendent sprinklers with a nominal temperature rating of 70 °C. The sprinklers were installed at 3 m×3 m spacing. The effectiveness of fire control of the sprinklers depends on ceiling height, sprinkler spray pattern, water drop size (as related to orifice size and discharge pressure), and sprinkler discharge rate. The test results show that the standard-response LO sprinklers at a discharge rate of 141 L/min per sprinkler did not control the test fire under a 12 m high ceiling and sprinkler skipping occurred. For a ceiling height of 16 m, the quick-response LO sprinklers discharging at a rate of 182 L/min per sprinkler were not effective in controlling the test fire and sprinkler skipping also occurred; however, the standard-response ELO sprinkler discharging at a rate of 209 L/min was marginally effective in controlling the test fire. For a ceiling height of 18 m, the K363 CMSA sprinklers discharging at a rate of 363 L/min per sprinkler either controlled or suppressed the test fire, because the sprinkler generates considerably large water drops and provides sufficient high discharge rate. The test series has demonstrated that water drop size is an important factor for achieving fire control or suppression of the high-ceiling-clearance fire scenario. With regard to the fire size at sprinkler actuation, the convective heat release rate of the fire is estimated from the gas temperature measured at ceiling level directly over ignition by using a plume correlation. Using a sprinkler with a RTI of 130 (m⁎s)1/2 under the 18 m high ceiling, the fire size at first sprinkler actuation was estimated to be 7-8 MW. The test results provide a technical basis for developing sprinkler installation rules for non-storage high-ceiling-clearance occupancies in the revised Chinese National Code of Designs for Sprinkler Systems.

► We investigate sprinkler effectiveness in a non-storage high-clearance scenario. ► A standard-response sprinkler rated at 72 °C under a 18 m high ceiling activated. ► The heat release rate at sprinkler activation is estimated to be 7–8 MW. ► Drop size, spray pattern and discharge rate are important factors for fire control. ► A K363 sprinkler at 0.1 MPa effectively controlled the fire under 18 m high ceiling.