Our customer needed the noise from their vacuum chimneys to be reduced so that the impact level on the surrounding residences was decreased in line with the local environmental health departmentís requirements.
Changing the quality of the paper required different pressures from the vacuum pumps, when these pumps were made to operate near their maximum level the noise produced radiated out of 4 stainless steel pipes at the roof level in the direction of the surrounding properties was enough to cause complaints to rise from the surrounding neighbours.
Airmatic Acoustics provided the solution to fit 4 1500mm wide by 1050mm high, 1800mm long attenuators into the discharge stack. The final installed design was a U bend design which took the discharge substance and noise and forced it along the new attenuator and duct sections. This came complete on galvanised steel frame sat on anti-vibration pads as there were extra requirements to keep the breakout noise into the room to a minimum.
The performance criteria of the attenuators was made clear at design stage with specific octave band targets being laid out by the acoustic consultant. Particular attention was brought to the 18dB reduction in the 63Hz octave band. On commissioning the acoustic consultant found that the criteria had been met at the 63Hz band and that the reduction was greater that the criteria in the rest of the octave bands.