Jalousie damper Adjustment values for L W in octave bands Correction Example values Octave band, Hz 63 125 250 500 1k 2k 4k 8k -7 -7 -10 -11 -12 -15 -17 -20 Tolerance: ± 5 dB 78 78 75 74 73 70 68 65 Example: The air velocity in a JSM 800 800 damper (0,64m²) is 8 m/s. The curves show a pressure loss of 400 Pa at the aperture (a) 48°, and a sound level of 87 dB (1m²). The present sound levels become: L W 0,64 = L W 1,0 + 10 x Log 0,64 = 87 dB - 2 dB = 85 dB The adjusted sound spectrum divided by the individual octave bands is shown by the values in the table for adjusted values. Tightness class Blade area m² – 0,6 0,6 – Tightness class 2 3 Maximum pressure difference Damper width 1400 1600 Pa 2500 2350 lindab | dampers and measure units JSM Lindab reserves the right to make changes without prior notice 3 2018-03-06
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