Sound Reduction Matting-
Enka-Silence 7020 -
Reduces Waterfall Noise with Enka-Silence 7020
Enka-Silence 7020 is a flexible, three-dimensional matting, produced from polyamide monofilaments welded together where they cross to form a tough, open structure. Enka-Silence 7020 is used as sound reduction matting in counter flow cooling towers: one or several layers of Enka-Silence, installed directly above the cooling water basin, reduce the waterfall noise substantially.
Enka-Silence 7020 Technical Data
Sound reduction of waterfall noise: Results of tests of Enka®Silence 7020 to attenuate waterfall noise in a
Tests have been carried out in a counter flow cooling tower, dimensions 5.50 m x 5.50 m, falling height 2.10 m, water volume 7.5 m3/h.m2, cooling tower basin depth 0.18 m.
Table 3: Reduction of Waterfall Noise Measured t 15 m (Fan on).
Table 4: Reduction of Waterfal Noise Measured at 4.5 m (Fan on)
Conclusions for Enka-Slience 7020
The tests indicate that Enka-Silence 7020 can be used to reduce the waterfall noise in a counter flow cooling tower. The data show that one layer of Enka-Silence 7020 reduces the water noise by 3.5 to 4.0 dBa. A second layer of Enka-Silence reduces the noise by an additional 2.5 to 3.0 dBa, and a third and a fourth layer reduce the noise by an additional 1.0 dBa each. The total water noise attenuation provided by all four layers of Enka-Silence 7020 ranged from 7.5 to 9.0 dBa. Enka-Silence 7020 was not very effective in reducing the overall cooling tower noise level
when the fan was run in addition to the waterfall. In this case, the overall noise level was attenuated by 1.4 dBa with four layers of Enka-Silence 7020. However, there was a noticeable reduction of 7 to 8 dB in the 4000 and 8000 Hz octave bands, which would change the sound characteristic of the cooling tower noise by reducing the high frequency noise components.
The data were corrected only for changes in the ambient noise caused by the changing
wind speeds (0 to 9.5 knots).
However, some minor anomalies in the data may be attributable to wind gusts.
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