TDC vs. TDF Profile
- Mated TDC and TDF Profiles
Lockformer’s TDC Machine (circa 1975)Smacna classifies any rolled on transverse connector as T25. Lockformer came out first with a TDC Rollformer (Transverse Duct Connector) and then Engel followed with their TDF Rollformer (Transverse Duct Flange). These machines rollform the Flange to the end of the Duct Joint, meaning that the Duct Wall and the Flange are one piece. TDC / TDF Duct is used in lieu of Ductmate Flange for the transverse connection (end to end) on medium and high pressure rectangular duct systems.
How to identify a TDC vs TDF profile:
On TDC the hem on the flange is on the outside; on TDF the hem on the flange is on the inside.
TDC (T-25a)
- TDC Profile
- Mated TDC Profile
- TDC’s raw edge on its turned out hem is a reason many shops, given a choice, would favor the TDF. This raw edge can be a safety concern when handling Duct on the Job Site
TDF (T-25b)
- TDF Profile
- Mated TDF Profile
Differences between machinery requirements to roll each T25a (C) and T25b (F) profile:
12 stations are required to form the TDC profile; 16 stations required to form the TDF profile. TDC machine is available as 12 or 16 station. TDF machine is sold only as 16 station.
- TDF Profile
- TDC Profile
- TDF Profile on Full Wrap Duct
Which is a better profile?
Though Smacna doesn’t differentiate between the two, the T25B (F) profile is often considered a better profile because it’s hemmed to the inside, not only adding strength but also leaving no exposed edge on the outer part of the duct. There are likely arguments in favor of the TDC profile, possibly as it relates to the components. Let’s let the duct fab shops determine this for themselves.