The air terminal unit manages supply air from a central air handling station by controlling the volume and temperature of the air supplied to a space via the air diffuser. It is usually placed very close to the occupied space to offer better air control.
The throttling process in terminal units cause duct-borne noise. Some terminal units are fan powered and may add noise to the air stream. Since the terminal units are located relatively close to the occupied space, the duct-borne noise becomes an issue.
Silencers placed downstream of VAV boxes can attenuate the duct-borne noise generated by terminal boxes. Vibro-Acoustics analysis can determine the attenuation requirements off VAV boxes based on manufacturer’s data and room noise criteria.
Maintaining a low pressure drop across Terminal boxes is critical to allow for effective air distribution. Catalogue selections may not take into account the system effect, thereby risk choking the system.
Silencers associated with Terminal units need to have very low applied pressure drops. Vibro-Acoustic systems approach takes into account the pressure drop with system effects.
Terminal boxes have space limitations since they are located relatively close to the diffusers. System effects may come into play for lack of duct lengths.
Vibro-Acoustics “Fit the duct” silencer philosophy takes into account the short run lengths and addresses them using extended casing silencers or elbow silencers.