Heating and air-conditioning systems often rely on ducting to move air around. This is great, but one of the problems it has is that the ducts can amplify machinery noise – such as the fan that is moving the air around.
In a work environment, controlling noise levelsis important, and employers have a duty to protect their workforce. One of the ways of reducing this noise is to fit a duct silencer.
What Is a Silencer?
A silencer – more accurately called an attenuator – won’t eliminate all of the noise that comes through your ducting, but it will significantly reduce it.
Silencers from ductwork parts suppliers such as https://www.dustspares.co.uk/ductwork-parts/ work by absorbing the sound that passes through the ducts. This is usually done by using material to absorb the sound waves. Mineral wool is commonly used for this. The thickness needed is dependent on the level of noise that you are trying to cut.
Another way of cutting the level of noise passed through a duct is to add baffles. This is how the silencer on a car exhaust works; it’s also the technique used in recording studios, where you see an egg box-like arrangement of foam on the walls. Sound waves like to travel in a straight line, and adding baffles stops them from doing that, which cuts the amount of noise transmitted. However, baffles can be a problem in ventilation systems because they also restrict the movement of air, which is not what you want. Restricting the airflow means the fan will have to work harder – that leads to more noise and you’re back where you started.
Cutting the noise in ducts may well therefore involve a combination of different techniques in order to find the correct level. This might mean using baffles alongside mineral wool in order to get an acceptable balance between noise and airflow.
Ideally, designing a new ducting system should take account of the amount of sound generated and plan to keep it down to a minimum. However, changes to the system over time may upset things and mean you end up with higher noise levels. Fortunately, it is possible to retro-fit a silencer in order to correct problems at a later stage and bring the system back down to a suitable noise level.