Designing a baghouse system requires careful calculation and optimization of multiple design variables to ensure reliable performance, regulatory compliance, and long-term durability.

What Is the Duct Size?

Well-designed hoods should minimize turbulence, maintain smooth airflow, and include air locks to prevent blowback into the system.

Well-designed hoods should minimize turbulence, maintain smooth airflow, and include air locks to
prevent blowback into the system.

Duct sizing refers to the calculation of the appropriate diameter for your system’s ductwork based on how much air (measured in CFM) needs to be transported and at what velocity (measured in feet per minute, or FPM). The goal is to select a duct size that allows for proper dust conveyance without excessive friction loss or particle dropout.

Duct Size Calculator

DUCT SIZE CALCULATOR

Formula:
Duct Diameter = √(Air Flow / Velocity / π) × 24
Duct Diameter = in.

Importance of Duct Size In Baghouse Design

Poor duct sizing can lead to a number of costly issues. If the duct is too small, it can create excessive static pressure, overloading the fan and reducing system performance. If it’s too large, air velocity may drop below the minimum transport velocity, causing dust to settle and clog the ductwork.

Correct duct sizing helps maintain transport velocity above minimum values (typically 3,500–4,500 FPM, depending on material). It prevents dust accumulation and blockages as well as reducing energy use by avoiding oversized fans.

Note: While this formula provides a solid starting point for duct sizing, it should not be used as the only basis for design decisions. There are many other factors a dust collection expert considers, including duct length and layout, number of branches and elbows, material characteristics (abrasive, sticky, etc) and fan capacity and system static pressure. 

We strongly recommend consulting with a dust collection expert, such as the team at Baghouse.com, before finalizing any ductwork layout. We can help tailor your system to your specific plant requirements and avoid costly design errors.