PacB Group // Mitigating Generator Noise: Silent Generators as an Effective Solution


Mitigating Generator Noise: Silent Generators as an Effective Solution

Generators, whether powered by diesel or petrol, often generate significant levels of noise that can be intrusive and harmful to both humans and animals. Silent generators constitute one of the solutions to mitigate the negative effects of generator noise.

Generators can have a significantly bad effect on human health. The internal combustion engines driving generators produce noise. Noise is measured in decibels, and noise over a certain decibel level can have adverse effects on human health. The excessive noise levels emitted by generators, especially when operating close to where people work or live, can cause irritation and even permanent damage to a person’s hearing. And with the worsening unreliability of electrical power supply from Eskom, the frequent use of small generators, particularly petrol-powered generators, has become common.

Small petrol-powered generators are typically chosen for affordability, so invariably lack any form of noise attenuation. As a result, the noise they produce can become a significant nuisance. Small generators are considerably less noisy than large industrial and commercial diesel generators are but are often used in residential environments, which means that they are being used close to where people live.


Silent Generators: A Practical Solution

To address the noise problem we mentioned above, the use of a silent generator is usually the only practical solution.

The higher the capacity of the generator, the worse the noise level will be. Large-capacity generators tend to produce more noise and require more effective noise-attenuation measures than small ones do. Silent generators are housed within sound-reducing containers or custom enclosures known as sound-attenuation enclosures. These enclosures are specifically designed to reduce the noise produced by the generator’s engine components. Silent generator enclosures are commonly constructed using materials such as glass-reinforced plastic composites. These enclosures incorporate a combination of hard materials to reflect sound energy back into the enclosure, along with soft and porous materials that absorb sound energy and convert it into heat. The design and materials used depend on the power output of the generator. A silent generator, housed in a properly designed sound-reducing enclosure, offers an effective solution to mitigate noise and create a more comfortable environment for those who live or work in it.


Optimising Sound Absorption in Silent Generators

Some materials excel at absorbing high-frequency sounds but struggle with lower frequencies. The varying abilities of materials to absorb sound means that different materials and techniques must be used in silent generators to achieve optimal noise reduction.

Different frequencies of sound require different, specific materials for effective absorption. The sound-absorbing properties of materials are frequency specific. Soft and porous materials are highly efficient at absorbing higher frequency sounds. Lower frequency sounds pose a greater challenge and require heavier layers of movement-resistant materials. Additionally, creating air pockets between thin panels can help deaden lower frequencies. The resonance effect generated by these air gaps converts low-frequency sound into higher pitches, which can then be absorbed by the porous materials in the enclosure.

Most silent generators incorporate multiple layers of materials with distinct sound-deadening properties to achieve optimal noise reduction. By combining materials that excel at absorbing different frequency ranges, generators can substantially reduce overall noise levels. In addition to the material layers, other measures such as engine exhaust silencers and vibration-absorbing isolation mounts play a significant role in minimising noise. Engine exhaust silencers reduce noise emitted from the exhaust gases, while isolation mounts prevent vibrations from being transmitted to the generator’s surroundings.

While generic sound-attenuating enclosures are commonly used, they may not deliver the best noise reduction for every generator model. To achieve truly silent generators, each enclosure needs to be engineered specifically for the intended generator model. Soundproofing must be designed to absorb the specific range of sound frequencies produced by the generator’s engine. Custom enclosures, although more costly, are reserved for sites where noise reduction is crucial. Reputable generator manufacturers typically have in-house noise-attenuation experts, and there are also specialised companies that focus specifically on building sound-attenuating enclosures. Achieving silent generators is a complex process that demands specialised engineering and tailored solutions to attenuate the specific sound frequencies produced by each generator model.


Understanding Noise Levels and What Constitutes Too Loud

Understanding noise levels and their potential impact on human hearing requires understanding of how sound levels are measured. Decibels (dB) are used to measure sound, and different thresholds indicate when noise becomes harmful. The concept of a silent generator is tied to how much noise in decibels it produces. The decibel requirement for a particular application informs which unit is required when purchasing or renting a generator. Decibels serve as a measurement unit for sound levels. To establish reference points, consider that a human whisper registers at around 30 dB, while normal conversation reaches approximately 60 dB. Prolonged exposure to noise levels consistently higher than 70 dB can start to damage hearing. Sound at about 110 dB causes potential hearing loss within as little as two minutes. Sound exceeding 120 dB can immediately and permanently harm the ears.

Noise above 80 decibels is generally considered “too loud,” and most people experience discomfort at levels exceeding 140 dB. It’s important to note that not all noise frequencies can be detected by humans. To account for sounds audible to humans, noise levels are annotated as db(A). A 50 kW diesel generator can produce noise levels around 85 dB(A), while a 1500 kW engine may exceed 105 dB(A), and generator noise can persist for hours or even days.


What Makes a Silent Generator Silent?

When selecting a commercial or industrial generator for purchase or rental, noise should be a significant factor to consider. Typically, generators falling within the range of 75-85 dB(A) at a one-meter distance are considered “silent generators.” This does not imply the complete absence of noise. Even the quietest and most costly silent generators, often referred to as “whisper generators”, produce some level of noise. Whisper units are specifically designed for use in environments where minimal background noise is critical, such as TV and film sets, hospitals, and other medical facilities. For critical applications requiring the absolute minimum possible background noise, whisper generators offer the highest level of sound reduction.


Choose an Acknowledged Expert in Power Generation

At PacB, we have established ourselves as a leading manufacturer in the power-generation industry. Specialising in the production of large, commercial, and industrial generators, we are aware of the noise challenges posed by large diesel gensets. We combine technical expertise and extensive experience to deliver optimal solutions for customers. From generator sizing to noise attenuation and system configuration, we combine a comprehensive understanding of site-specific conditions with technical know-how to provide a solution for your specific requirements.

For guaranteed, quiet, electrical power generation, make us your go-to provider. Whether it’s large silent generators or specialised control systems, we offer industry expertise, superior quality, and reliable service. Contact us today to discuss your power requirements and benefit from our expertise in delivering exceptional solutions tailored to your needs.

Our qualified technicians offer support and advice in the selection of the right power solution for your needs by calculating your power requirements.

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