Can-Fan Silencer 125mm 45cm

A 45 cm silencer with 125 mm flanges, for fitting into the duct behind a fan.

A silencer does not remove all the noise from an extraction system. It removes one kind, and it helps to know which, because that decides whether this is the part that solves your problem.

Which noise this takes out

Noise from an extraction system comes from three sources. The sound the impeller makes, travelling out through the duct. The sound of air rushing past bends and edges. And vibration carrying through the mounting into the structure.

This silencer addresses the first. Inside it is mineral wool, which absorbs sound energy from the air passing through, so that less of it emerges at the end of your duct run.

What it does not do is solve the other two. A fan droning because it is hauling against a clogged filter will not be quietened here, and neither will vibration running through a bracket into a wall. For the first, look at the filter; for the second, at how you have hung it.

Where to fit it

The usual place is directly behind the fan, on the side the air leaves. That is where the noise you want to stop sits before it travels into the rest of the ducting.

Beyond that this part is not fussy: it can also go behind a volume controller or at an air inlet grille, anywhere noise is being passed along 125 mm ducting.

Build

The casing is galvanised sheet steel, with the flanges fixed mechanically using screws and rivets rather than bonded. Steel makes sense here because the part has to enclose a filling and hold its shape while hanging off a duct.

Technical Specifications:

• Flange size: 125 mm
• Length: 45 cm
• Casing: galvanised sheet steel
• Filling: mineral wool
• Placement: behind a fan, volume controller or inlet grille
• Construction: flanges fixed with screws and rivets

Frequently asked questions

Will this make my extraction silent?
No. A silencer reduces noise travelling through the duct. Vibration and flow noise remain.

Which side of the fan should it go?
Usually the discharge side, directly behind the fan.

Will it fit my 125 mm ducting?
The flanges are 125 mm, so you couple it with clamps to compatible ducting of that size.

Does this cost me airflow?
A little. Every extra length of duct adds resistance, so allow for it when choosing your fan.