One of the most common concerns around generators is the noise. There’s an image in the public mind that generators are always large, noisy, dirty and smelly. Perhaps that was true 30 years ago, but in recent years manufacturers have focused on reducing everything from size, to fuel consumption, to safety risk and above all, noise. Today’s generators run at noise levels far below their predecessors. In many situations, generators need to be very quiet indeed – for example in hospitals where a generator is situated near to patients or staff. Apart from the obvious, there are many reasons why customers would choose to purchase a genset that’s as quiet as possible.
Diesel generators produce most of their noise due to the combustion process involved in how they work. Diesel fuel is injected into the engine’s cylinders and is ignited, producing the motive power in the pistons which ultimately is turned into electricity. The ignition, combustion and movement within the cylinders generates a lot of vibration and noise. Diesel engines also require a high level of air intake to support combustion, which creates additional noise from the intake and exhaust systems. Diesel generators also often use cooling fans to regulate the engine’s temperature, which can also contribute to the noise level. Not all generators are equal, and generally, the larger the generator (in terms of power output), the louder the noise it will produce.
Like most things in the world of sound, generator noise is measured in dBA (decibels in other words). A common maximum noise level for generators is 75dBA and this can be likened to: the volume of a vacuum cleaner from a distance of 1 meter, a washing machine or dishwasher, hairdryer or a crowded restaurant.
Believe it or not, using the right combination of acoustic attenuation, muffling and enclosures, it’s usually possible to reduce the maximum volume of even the largest generators to these modest levels.
To reduce noise levels, manufacturers of diesel generators use various sound-dampening technologies, such as mufflers and insulation materials.
Insulation materials reduce the transmission of noise from the engine to the surrounding environment. This includes using sound-absorbing materials on the engine casing and acoustic barriers around the generator.
Mufflers are used to reduce the noise emitted from the exhaust system. They work by absorbing and reducing the sound waves created during the combustion process. Sound attenuation equipment can be applied to generator inlets and outlets, and can also include exhaust silencing systems.
Anti-vibration mounts are used to reduce the vibrations that are transmitted from the generator to the surrounding environment. These mounts are made from materials that can absorb and isolate the generator’s vibrations.
Enclosures are used to contain the generator and reduce noise levels. These enclosures are made from sound-insulating materials and can be designed to provide adequate ventilation and access for maintenance. Find out more about acoustic enclosures.
Manufacturers can design engines with quieter components, such as quieter fuel injectors, valves, and turbochargers, to reduce the noise level produced during operation.
The design of the cooling fans can also impact noise levels. Manufacturers can use fans with fewer blades or variable speed fans that produce less noise.
The location of the generator can have a significant impact on noise levels. Often larger generators are housed in their own dedicated rooms which can be isolated from other buildings and soundproofed. However, even with these measures in place, diesel generators are generally louder than other types of generators.
Comfort: Silent generators provide a more comfortable environment, especially in residential areas, where noise pollution can be a significant problem. In highly populated environments such as schools and hospitals, noise levels must be kept at a minimum. Prolonged exposure to high noise levels can cause hearing loss or problems such as tinnitus (ringing in the ears). It can also be very stressful and can even lead to issues such as high blood pressure and anxiety. It’s also associated with disrupted sleep, leading to lower productivity and wellbeing. For all these reasons, choosing a power generator that is a silent as possible is highly recommended.
Noise is a frequent consideration in many of our generator installation projects. For example, when we installed three 1900kVA generators for a leading telecoms provider, a maximum noise level of 75dba was specified. We achieved this through designing a bespoke acoustic enclosure fitted around the generators. More about this project. In generator installation projects, we will take permitted sound levels into account when designing and specifying the system.