Early Suppression of Rack Storage Fires with K363 Standard Response Sprinkler

Abstract

A series of five large-scale fire tests has been conducted to evaluate the fire suppression performance of a standard-response large K-factor pendent sprinkler for protection of rack storages of Standard Plastic Commodity under a 9.1 or 12.2 m high ceiling. The sprinkler has a nominal 25.4 mm orifice diameter and a nominal 363 L/min/(bar)1/2 discharge coefficient (K-factor). The activation mechanism is a standard-response solder link, rated at 72°C, with a Response Time Index (RTI) of 130(m-s) 1/2. The sprinkler spacing was maintained at 3 m by 3 m and the deflector to ceiling distance was 343 mm. Test variables included sprinkler discharge pressure, storage height, ceiling clearance and ignition location. Two fire scenarios were used to evaluate the fire suppression performance of the sprinkler: 1) a fire between two sprinklers with low ceiling clearance (1.8 m) to evaluate sprinkler spray overlapping ability; 2) a fire underneath a sprinkler with large ceiling clearance (3.4 m) to evaluate sprinkler spray penetration ability against the fire plume. For 12.2 m ceiling height, the sprinkler at a discharge pressure of 0.21 MPa and a sprinkler discharge rate of 522 L/min achieved fire suppression for both the two fire scenarios. For the 9.1 m ceiling height, the sprinkler at a discharge pressure of 0.07 MPa with a discharge rate of 302 L/min or at a discharge pressure of 0.10 MPa with a discharge rate of 369 L/min provided fire suppression performance for the first scenario. For the second fire scenario under a 9.1 m high ceiling, the sprinkler at a discharge pressure of 0.07 MPa with a discharge rate of 302 L/min only achieved fire control. Actual Delivered Densities (ADD) of the sprinkler for some of the test conditions employed in the large-scale fire tests were measured. The large water drops generated from the large K factor (K363) sprinkler enhance its penetration ability against the fire plume. The ADD data confirm that as ADD greater than Required Delivered Density (RDD) for fire suppression, suppression of the fire can be expected. The results of the five fire tests show that a standard-response K363 sprinkler can be as effective as ESFR sprinklers in providing protection for storages in warehouses with ceiling height up to 12.2 m.