A short-radius 45-degree elbow is choking a high-velocity round duct

A tight pleated elbow can create system effect and turbulence on high-velocity duct. Use an approved smoother/longer-radius fitting or revised route where the system needs it.

Stop if

• This 45 on the high-velocity round run is a tight pleated fitting near [equipment/location]. It may be causing turbulence. Do you want a smoother/longer-radius fitting or a revised offset path?

Watch out

• Do not use a cheap tight 45 elbow in a high-velocity location just because it physically clears the obstruction.

Check

• Confirm duct velocity/pressure class and where the fitting sits in the system.
• Look for noise, vibration, or fan performance complaints.
• Check whether the elbow is pleated/light-duty or smooth/heavy-duty.
• Look for straight duct requirements near equipment.
• Confirm revised fitting with foreman/detailer/TAB if performance is affected.

Steps

• Confirm duct velocity/pressure class and where the fitting sits in the system.
• Look for noise, vibration, or fan performance complaints.
• Check whether the elbow is pleated/light-duty or smooth/heavy-duty.
• Look for straight duct requirements near equipment.
• Confirm revised fitting with foreman/detailer/TAB if performance is affected.

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