Price: $49/year for student members; $399/year for professionals.
Includes: Full DFDB online, plus all ASHRAE handbooks and standards.
If you are a full-time engineering student, ASHRAE offers deep discounts. While they may not give away version 6.00.05 specifically (they push newer versions), many university libraries have an ASHRAE Digital Library subscription. Ask your librarian if they have a site license that includes the DFDB. Alternatively, professors can request evaluation copies for a semester. ashrae duct fitting database 6.00 05 free download
If the cost of the official ASHRAE software is a barrier, or if you simply need the data, consider the following legitimate alternatives: C. Official Purchase
A. The ASHRAE Handbook (Hardcopy/PDF)
B. Free Online Calculators While they may not have the official "ASHRAE" branding, many HVAC engineering websites offer free calculators based on the same loss coefficient equations. Price: $49/year for student members
C. Official Purchase