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Square to Rounds

Ventilation Ducting  | Rectangular Ductwork |  Square to Rounds

Ductwork Transistions

Square to Rounds

Ductwork square to rounds, as the name suggests, convert square or rectangular ductwork to round wherever such a transition is required. This may be to connect rectangular ductwork to ventilation equipment designed for a circular connection, or to change the duct shape to pass through a confined space. In confined areas such as ceiling voids (the space between the suspended and structural ceiling of a building) it's common to see ductwork runs comprised of both rectangular and round spiral duct - the main duct and branches are rectangular as the equivalent sized round duct may not fit into the ceiling void. Square to rounds provide the means to make this transition.

Note that rectangular ductwork is made to order. Please therefore take manufacturing time into account when scheduling your project.

There are many possible shapes and sizes of square to rounds. Most are symmetrical but some may be offset to one side or two sides. We are able to manufacture any square to round required if a clearly dimensioned drawing is supplied to us. Otherwise it is possible to order them online but with limitations to the size and general design (symmetrical and offset to one side - one side is flat - can be defined on the website). Square to rounds offset to two sides and/or with a larger offset will require a drawing.

In accordance with DW144 we manufacture square to rounds with a maximum slope angle of 22.5°. We use a maximum of 30° for offset square to rounds. If there is a substantial difference in size between the square and round ends it can mean that the square to round is quite long. For example a 750x600 down to will 125 dia will be approx. 850mm total length. You can provide your own overall length in the "Any other info" box if required. You may also email us for an image of the square to round you intend to order (please provide dimensions and use "Image required" in the subject field of your email).

This is useful to ascertain the default length and to determine whether you need to stipulate your own length due to space restrictions. Note that, in terms of airflow, the higher the slope angle the more inefficient the the square to round becomes.

Note that with offset square to rounds the flat side will correspond with the 'width' side. If you require the other side to be the flat side i.e the 'depth' side as shown in the drawing, go back and make the width the depth and vice-versa.

If you need to calculate the size of the square end of a transition piece relative to the round end, or vice-versa. Please use the link below:

How to calculate square to round transition sizes..

(If you're interested in buying just the flat pattern for a square to round click here)

Please use the drop-down menu below to select the width of the square to round required as depicted in the drawing to the right. Depth, diameter, and style can be selected on the following pages.


Ductwork Square to Rounds
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