8-Inch Long-Radius 90° Airflow Duct Elbow

Description

Overview

A long-radius 8-inch 90-degree elbow — bend radius 175 mm, R/D 0.858 — for duct runs where the turn should cost as little as possible. Applying published duct-loss relationships to the geometry gives a computed loss coefficient of 0.40, against 1.04 for our compact 90 and 0.92 for two 45s in series. Those figures are computed from geometry using published relationships; they are not measurements from our bench, because no flow bench has been run on any part in this line.

The trade is space. At roughly 304 × 209 × 304 mm this elbow needs substantially more room than the compact 90. If the duct has to turn inside a tight shelf gap or against a wall, the compact elbow is the one that fits; this one is for runs with room to sweep.

What it fits

• 8-inch rigid snap-lock pipe, socket at both ends.

Rigid sockets only. The socket bore accepts rigid pipe at nominal OD; it cannot take a flex-duct core directly, because HVAC flex slips over a male end rather than into a socket. To continue in flex, add the 8-inch flex duct adapter or a hardware-store metal splice collar.

Measure before you order. Fit dimensions in this line are derived from published fan and chassis geometry and are not yet validated against measured production hardware. Check your flange size and clearances against the footprint below. If something does not fit, tell us — that is how the next revision gets better.

How it is used

Seat rigid 8-inch pipe in the socket at each end where the run turns 90 degrees — up a wall, over a shelf, into a window drop. Give the long sweep the room it asks for; that sweep is the entire reason this part exists. Where the run continues in flex rather than pipe, put the flex adapter in the socket first.

Why it helps

• The gentlest 8-inch turn in the line: computed loss coefficient 0.40, against 1.04 for the compact 90 and 0.92 for two 45s in series — per published duct-loss relationships.
• Both ends are the line’s standard 8-inch rigid sockets, so it drops into an existing run.
• One purpose-shaped bend instead of stacking two 45s and a coupler.
• Honest status: the coefficients are computed from geometry, not measured; and this elbow needs real space — measure the corner before you order.

Specifications

Open source

This design is open source under CC BY-SA 4.0. The files are free to download at /3d-models/, and anyone may print, modify or sell them — that is the point. Buying a finished part from us is one way to support the work; the fund is another.

Works with

Slots into the 8-inch rigid fitting family:

• 8-Inch Compact 90° Duct Elbow
• 8-Inch 45° Duct Elbow
• 8-Inch Duct Coupler

See the full D-Central shroud and ducting system.

Frequently asked questions