The database differentiates between stamped elbows (smooth radius) and pleated elbows. It breaks down losses based on the radius ratio ($R/D$).
Consider a 10,000 cfm (4.72 m³/s) system with 50 fittings, 80% elbows, 20% tees. Using the 1994 database at 15 m/s reference:
The 1994 edition was one of the first ASHRAE publications widely scanned and distributed as a searchable PDF. Unlike older scanned texts, high-quality versions of the 1994 database are OCR-friendly, allowing engineers to quickly find fitting types using keywords like "round 90-degree mitered elbow" or "rectangular converging tee." duct fitting database -ashrae 1994- pdf
The 1994 database was developed to automate the manual process of looking up fitting data in the ASHRAE Handbook. It established a standardized library of fittings—ranging from elbows to transitions—each assigned a specific code and associated mathematical model for pressure drop calculations.
| Feature | 1994 Edition | 2005 Edition | 2017 Edition | | :--- | :--- | :--- | :--- | | | ~250 | ~300 | ~350+ | | Flat oval data | Basic | Improved | Extensive | | Digital support | None (PDF only) | CD-ROM with search | Online interactive tool | | Reynolds correction | Limited | Moderate | Full (Re 100 to 10^7) | | Best for | Legacy systems, education | General purpose | New construction, LEED | Using the 1994 database at 15 m/s reference:
When a duct expands or contracts, the air velocity changes. If the angle of expansion is too steep, flow separation occurs, essentially stalling the air. The includes charts showing the optimum angle of expansion (usually around 15 degrees or less) to minimize pressure loss. It documents the losses for abrupt transitions versus conical transitions, allowing engineers to weigh space constraints against energy efficiency.
Provides inputs like flow rate , density , and dimensions to output velocity , velocity pressure , and the loss coefficient (C) . | Feature | 1994 Edition | 2005 Edition
Because this is a 1994 scan, Optical Character Recognition (OCR) can mistake numbers. For instance, a "Co = 0.22" might be read as "Co = 0. ZZ." Always cross-reference with the original scanned image if a value seems illogical.
Why would you pull out a 30-year-old PDF instead of using modern tools? Several real-world scenarios demand it: