: It covers round, rectangular, and flat oval duct fittings for supply, exhaust, and common duct functions. Integration with Excel
-factor varies dynamically based on geometric ratios (e.g., aspect ratio, radius ratio) and flow ratios (e.g., flow rate fractions in branches vs. mains).
Data can be easily exported or imported from CAD software. How to Build or Implement an ASHRAE DFDB in Excel
: Add the pressure losses of all fittings, straight ducts, and equipment (like filters or coils) to determine the total fan static pressure required. Core Calculation Formulas
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is the total pressure loss (in inches of water column or Pascals) Ctcap C sub t is the non-dimensional total pressure loss coefficient Pvcap P sub v is the velocity pressure, defined as (in IP units) or (in SI units) The provides empirical Ctcap C sub t
The official ASHRAE DFDB software contains thousands of these Cocap C sub o
Junior engineers can utilize standardized company templates to reduce human error in calculations. Structuring the Excel Database : It covers round, rectangular, and flat oval
The Ultimate Guide to the ASHRAE Duct Fitting Database Excel: Streamlining HVAC Design
Each fitting in the database is associated with a specific loss coefficient ( C0cap C sub 0
The database has evolved through multiple versions. Version 5.0 introduced modifications to numerous fittings, including CD3‑9, ED1‑4, ER1‑2, SD1‑2, and SR1‑1, among many others. Version 6.00.05 added an integrated database and real‑time calculation updates. Always verify that you are working with the most current data for your region and application.
The standardized ASHRAE fitting identifier (e.g., CR3-1 for a round elbow). Data can be easily exported or imported from CAD software
For tees, wyes, and branches (Category 5), always verify whether the -factor applies to the common velocity ( Vccap V sub c ), branch velocity ( Vbcap V sub b ), or main velocity ( Vmcap V sub m
). Include a correction factor input cell if designing for high-altitude projects.
often recommend building a custom Bernoulli-based spreadsheet and manually plugging in the coefficients provided by the DFDB for the most reliable results. While some modern BIM software like Revit attempts to automate these calculations, engineers often report that Revit's internal database can be unreliable, making the standalone ASHRAE tool a necessary cross-check. Duct Fitting Database - ASHRAE