... brass alloy, chrome plating 3.DN15(1/2")DN20(3/4" fire sprinkler different type: pendant type, upright type, ... 4Mpa)(3) strength test pressure: 30bars(3Mpa)(4) thread: 1/2”,3/4”(5) flux coefficient: 80,115(6) ... model: T-ZSTX20(pendent): installed downward, protected area: 4.9m2 x 4.9m2 Flow calculation: Q=K(10P)0.5 ZSTZ ... .P 1.2Mpa DN 20mm, connect thread R3/4”, flow coefficient 115, rated W.P 1.2 Mpa ...