Noise Problems And Solutions

If a noise level problem occurs at commissioning stage, it is recommended that the following basic procedures are employed to determine if the ATD is responsible .

1....Shut down in rotation the various Plants serving the conditioned space to identify which system is creating the noise. Do not be misled by the possible air imbalance created within the conditioned space i.e. supply only creating noise by air escaping through decor etc.

2....On the noisy system check the position of ATD dampers. If these are properly closed , open dampers .if the noise level is reduced hen damper generated noise is probably the cause. Solution : consider introducing duct dampers well upstream of the ATD to provide required pressure drop for balancing. This could involve the use of secondary silencers downstream of the new damper.

3....If opening and closing of ATD damper does not result in any significant change of noise level, either the noise is entering the conditioned space through some other path i.e. structure borne vibration, direct transmission through walls, ceiling or floor, duct breakout etc. or is propagating down the duct from another noise source.

4....Remove ATD and associated damper. If the noise level reduces then the source of the problem may well be ATD and damper. But if the noise level increases it is likely that duct borne noise is propagating down the system from some upstream source, possible main control damper, primary fans, poorly designed duct junctions etc. However, should investigation indicate that the noise problem is associated with the ATD / damper / plenum box combination, then consider remedial measures such as:

(i)....Replacing ATD with one of greater free air or even larger device

(ii)....Re-design the plenum box (possibly increasing the number of air inlet spigots)

(iii)....Increase the number of ATD's

Cost implications of remedial action should be the noise problem occur with an ATD clearly emphasize the importance of total consideration at Design stage to correct selection.