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Reduced Hand Dryer Noise

Conventional hand dryers can emit up to 83dB of sound when in use. This is the equivalent of the traffic noise that you would hear when standing next to a busy road. The combination of low and high frequency sound from a hand dryer can easily pass through walls and doors into surrounding areas and has even been linked with causing hearing problems for younger children who may be closer to the source of the noise.

Why hand dryers make so much noise

The design of a conventional warm air hand dryer produces a great deal of noise. There are two main causes of this noise:

  • The sound of the fan and motor
  • The turbulence caused by the airflow from the nozzle

These two factors combine to generate an unpleasant sound that can be extremely disturbing and may put some people with noise sensitivity off using the dryer altogether.

Fan noise from hand dryers

The design of a warm air hand dryer requires a relatively large nozzle to be used. This allows air to move slowly enough to pick up warmth from the heating element so that it can cause water to evaporate. Unfortunately, the size of the nozzle means that there is nothing between the fan system and the outside of the dryer, so all the noise of the motor and fan can be heard. The motor and fan noises tend to be quite high frequency which can be unpleasant in the area immediately around the dryer.

While it is possible to install some sound proofing on the sides of the dryer, this has very little impact on the amount of noise released overall.

Turbulent air

The wide nozzle of a warm air hand dryer also creates a turbulent flow of air out of the dryer. Turbulence can be useful in terms of slowing the movement of air and allowing it to stream around the user’s hands, however the effect of multiple streams of air moving at different speeds and colliding with each other causes a whooshing or booming noise.

The lower frequency noises from air turbulence are more likely to escape through walls and into the surrounding area where they can affect the concentration of people working nearby or disturb people in a restaurant or bar setting.

 

Low noise alternatives

Modern jet hand dryers such as the Mitsubishi Electric Wave range work in a different way to conventional dryers which helps to reduce the amount of sound produced.

In a jet hand dryer, air is blown over the skin at high speed from a narrow slot to displace droplets of water from the skin.

The design of airflow from a modern jet hand dryer avoids the two main sources of noise from a conventional model.

The narrow slot means that the air flows in a much more directed and smooth manner. Laminar airflow does not produce the noise of turbulence that a wider airflow creates meaning that low frequency noises are avoided.

The internal aerodynamics which are used to accelerate the air inside the hand dryer also act as a physical barrier between the fan system and the surrounding area.  When coupled with good quality soundproofing around the inside of the casing for the hand dryer, noise is reduced significantly.

With a “hands-in” design such as the Mitsubishi Electric Wave i01 hand dryer, the drying area is also contained, which means that there is even less opportunity for sound to escape.

As a result of the design of a jet hand dryer, the amount of noise in the surrounding area is far lower – around 57dB, or the equivalent of a quiet conversation.

Find Out More

Learn more about how low noise hand dryers could benefit your workplace by reducing unwanted noise. Enjoy a quieter environment with less distraction by choosing jet hand dryers from Mitsubishi Electric. Contact us today to request a demonstration of our full range.

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