Concentric Reducers for Ventilation Duct

Concentric Reducers for Ventilation Duct

What is a duct reducer?

A concentric reducer is a basic peice of metalwork that is used as a duct adapter to decrease (or increase) diameters of a duct system.

They are either pressed or fabricated. The majority of pressed reducers are in the size range upto 315mm diameter, however some sizes within this range (which are classed as non-standard) will be fabricated. Diameters from 355 upwards are fabricated i.e a specialist metal worker will make them with there own fair hands.

• A reducer is a fitting used in ventilation systems between two pipes of different diameters. Concentric reducers adapt the pipe and enable a change of diameter on a duct run to assist air flows.
• Reducers up to 315mm diameter are pressed reducers (for Standard Sizes), 355mm and above are fabricated reducers.
• Reducers for spiral ducting are all male fittings and fit directly into circular spiral ducting (secure using recommended fixing methods).
• For a male to male connection i.e reducer to spigot a Female coupler should be used.

What is the difference between a concentric & eccentric reducer?

• All of our reducers are concentric, eccentric reducers are available on request.
• A concentric reducer, is shaped like a cone and the centre line is directly in the middle of the two diameters.
• An eccentric reducer has an edge that is parallel to the connecting pipe and creates an offset in the centre line of the ventilation duct run.

Will a reducer have an effect on airflows and noise levels?

In short, it all depends on how your ducting system has been designed. It is possible. There are many variables, the duty of the fan, where the reducer is situated within the duct run etc, etc.

Be aware that a negative change in diameter can have an impact on the airflows within the duct system, as the air is forced through a smaller area it can create more resistance and more noise.

Reducers can also be used as enlargers i.e they can be used to increase the diameter, this can have the added effect of reducing the resistance and noise levels.

It is advisable to only use reducers to make adaptations to the duct diameter if it is absolutley essential.

What is the most common common size of ducting reducer?

Our most popular size of duct adapter  is a 150mm to 100mm reducer. Don’t worry we look at our sales and make sure we have stock for your orders.

Can I use the steel reducers for extractor fans?

You sure can, but also take a look at our plastic duct reducer 150mm to 100mm as many resdential systems utilise plastic ducting for house ventilation.