Rectangular straight attenuator Smoke single compartment Calculation example Pressure loss and flow noise depend on the velocity on the face area of the attenuator A. This is illustrated in the following example: SLRSS2 900 × 600 mm, Length 1,5 metre, 3 splitters, distance 100 mm. Flow = 7776 m 3 /h = 2,16 m 3 /s. Area A = 0,9 m × 0,6 m = 0,54 m 2 Face velocity = 2,16 m 3 /s = 4 m/s 0,54 m 2 Pressure loss: Pressure loss = 39 Pa. Pressure loss Pa 100 90 L=1,0 m L=1,5 m 80 70 60 50 40 30 20 10 0 0 1 2 3 lindab | fire & smoke SLRSS2 s=100 mm 4 5 v (m/s) 6 7 8 9 Flow noise from inlet: Lw i = 44 dB(A) -3 = 41 dB(A) (-3 from area correction) Flow noise from outlet: From graph: Lw o = 36 dB(A) -3 = 33 dB(A) (-3 from area correction) Sound power level, inlet: Lw i 60 50 s=100 mm 40 dB (A) 30 20 10 A [m²] 0,5 0,6 0,7 0,8 0,9 1,0 2,0 3,0 4,0 5,0 Kor. -3 -2 -2 -1 0 2 3 5 6 7 0 0 1 2 3 4 5 6 7 8 9 v (m/s) Sound power level, outlet: Lw o 60 s=100 mm 50 40 dB (A) 30 20 10 0 0 1 A [m²] 0,5 0,6 0,7 0,8 0,9 1,0 2,0 3,0 4,0 5,0 Kor. -3 -2 -2 -1 0 2 3 5 6 7 234 56789 v (m/s) Lindab reserves the right to make changes without prior notice 4 2021-11-04
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