More Fan Noise Attenuation Products
“More Ways to Control Industrial Noise”
A galvanized ndustrial noise control enclosure provides attenuation from an exhaust fan
Industrial Noise Enclosures
Industrial noise enclosures reduce radiating noise from a complete fan or blower assembly. While silencers on the inlet and outlet attenuate noise escaping from the openings, the walls of the noise enclosures attenuate the radiating fan housing noise and the motor noise. There are two types of enclosure materials. The first comprises rigid metal wall sections with absorptive materials sandwiched in between. The second option is constructed of noise blankets hung on a metal framework. Options for both enclosures are extensive, with access panels, doors, acoustic louvers, and windows as typical selections. Both enclosure types have their advantages, either better attenuation or easier to move if necessary.
Noise wraps are primarily applied for attenuating radiating fan housing noise. The wraps or blankets cover the fan or blower scroll and are used in conjunction with inlet and outlet silencers. Fan noise wraps are sized based on the fan dimensions, often from a fan drawing, which ensures the noise wrap fits the housing or specific area of the fan. The form-fitting wrap is held together with Velcro or a heavy cord. The blanketing material comprises a high-mass noise control barrier with a lightweight acoustical fiberglass absorber. Most often, blankets are used where a low level of noise is mandatory.
Noise blanket wrapped around an industrial fan housing
This fan has acoustic flexible connectors on both the inlet and outlet of the fan
Acoustic Flexible Connectors
Acoustic flexible connectors are often neglected but are a significant upgrade over conventional flexible connectors. They address vibration and alignment and attenuate breakout noise at a fan or blower’s inlet and outlet connection points.
Various flexible materials exist, but standard belts are EPDM and silicone impregnated fiberglass. Specialty flexible belts include high-temperature PTFE, FDA-grade PTFE, and Viton. Acoustical flex connectors are designed for both the inlet and outlet of the fan or blower. A metal “flow” liner is included in the design for increased attenuation. It is added in applications where abrasive materials are being conveyed or if the flex connector is on the fan’s inlet side (negative pressure). Acoustical flex connectors are custom built to fit each specific application.
Preassembled Attenuated Fan Packages
Large building ventilation is necessary for compressors or engines that generate excess heat. A series of supply air and exhaust fans are required to ensure proper airflow through the space. Since the buildings are so large, multiple fans are required and often run simultaneously, which increases the noise levels significantly. A solution for moving large airflows while minimizing noise is preassembled fan packages. Preassembled fan packages include a fan paired with a silencer, weather hood, and damper, and since the units are preassembled, there is minimal installation involved. These preassembled fan packages are considered “drop-in” designs and are easily lifted onto a roof curb or inserted in a wall opening. Options include various materials of construction, EXP motors, dampers, actuators, air filter assemblies, VFD controls, louvers, bird screens, weather hoods, and diffusers.