Illustration of Methods Used to Control the Noise of Generator Set

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There are six basic strategies for controlling noise of generator set.

1. Acoustic barriers

Rigid barriers that have substantial mass and stiffness reduce the transmission of sound energy. Examples include sheet steel typically used in enclosures and sand-filled block walls or poured concrete walls used in indoor locations. As there has been a trend to lighter-weight sheet steel for enclosures as a cost-saving measure, it is sometimes necessary to install reinforcing ribs when steel enclosure walls lack sufficient stiffness. Steel panels can also be covered with a barium-filled rubber mat that adds mass and is very effective at preventing the transmission of low-frequency sound.

2. Acoustic insulation

Sound-absorbing acoustic foam is effective for controlling high-frequency noise and is used extensively in outdoor enclosures. In indoor installations, it can be very effective at reducing noise when used to line air ducts or when used as a wall or ceiling covering. Generator set manufacturers generally offer sound-attenuating enclosures for units up to about 2,000 kW.

3. Vibration isolation

Vibrating generator components induce pressure waves as sound into the environment. Also, anything that is attached to the generator set can cause vibrations to be transmitted into the building structure or foundation. These attachment points include skid anchors, radiator discharge air ducts, exhaust piping, coolant piping, fuel lines and electrical conduit.

4. Attenuation of cooling air noise

The movement of cooling air is a significant source of high-frequency noise, but restricting its flow is detrimental to generator set cooling efficiency. More than 20 cubic meters per second of air is required for cooling a 50-liter diesel engine generators.

5. Exhaust silencers

Silencers are available in several different sound-attenuation grades, commonly referred to as industrial, residential or critical/hospital.

6. Maximize the distance from the source

Noise zoning ordinances typically set noise limits based on what can be measured at the property line.