Heat Shrink for Duct BandsThermofit Wraparound Duct Bands (TWDB) is Raychem's (now called Covalence) product fpr solving the problem of costly joint leaks in air conditioning duct systems.
This duct sealing band, made of cross linked polyolefin heat shrinkable material, is precoated with a hot melt adhesive. When heated in excess of 250F, TWDB shrinks and the adhesive melts, forcing it into all surface irregularities. Mechanically strong, pressure tight seals are provided.
Ducts can be assembled on the floor and raised into position shortly after installation. TWDB's cut to length system keeps inventory cost minimal by eliminating the need for multiple sizes. Its wrap around design makes it suitable for flat oval and rectangular duct as well.
Used in high velocity systems operating up to 158F, TWDB is non toxic and resistant to solvents and vibration. Shelf life is unlimited. This product offers an efficient, neat and permanent method for sealing duct joints, all at a low installed cost.
As you see here, the installation procedure is quite simple.
1: Cut TWDB to appropriate length. Recommended overlap is 2 inches onto itself.
2: Using a heat resistant tape (supplied) secure the TWDB end by taping it in place to form the TWDB into a circle (or rectangle).
3: Using a standard propane torch, heat TWDB on all sides until it has shrunk uniformly and adhesive is showing at each end.