Ductwork Cowls: Benefits, Uses and Applications | Dust Spares

August 26, 2020 Team Dust Spares Comments

When Will I Need To Use A Cowl?

A cowl is a hood-shaped covering of a chimney stack or ventilation discharge. These are used at the end of ducting systems when air is discharged to the outside. You will need to use a cowl if your ducting system exits the building via the ceiling or a wall.

Benefits And Uses Of Cowls

The advantages of using cowls is that they reduce the chance of animals, debris and rain from entering the ducting system. High Velocity and Swedish Cowls are used to increase draft / velocity to prevent backflow or re-entrainment of product or fumes back into the building.

Applications Of Our Cowls

The cowls that we offer have different applications as they are used for different purposes. For example, the Bird Beak with mesh and China Man Hat / Weather Cowl prevent rain and birds, whereas the High Velocity and Swedish Cowl only prevent rain from entering the ducting system.

- Bird Beak with mesh – this cowl is used for horizontal extraction from the side of a building. It has an overlapping top to prevent the rain from going through the mesh, which is there to prevent animals and debris from entering.

- High Velocity Cowl – this cowl is used for the vertical extraction from the roof of a building. This has higher weather protection for ductwork exhaust stacks and prevents rain from entering the ducting – due to the rain falling at an angle and bypassing the opening. These are used to increase the draft / velocity of the discharge to escape the boundary layer.

- Swedish Cowl – this cowl is used for the vertical extraction from the roof of a building. It contains a piece of galvanised steel to allow the rain to flow past the entrance of the ducting.

- China Man Hat / Weather Cowl – this cowl is the smallest for vertical extraction that we offer. It has a wide angled top to direct the rain away from the entrance and a narrow gap between the top and ducting to reduce the risk of anything getting in. However, this type of discharge is advised by the HSE not to be used as the discharge will be directed back towards the building – allowing smells to occur or the discharge to enter back into the building.

Please contact us if you require a bespoke size, or if you are unsure which cowl is best suited for your application and our experts will put you in the correct direction.