Isolation device in a heating and sealing system

A protective packaging formation device, comprising:

• an inflation assembly having a fluid conduit that directs fluid between first and second overlapping plies of a web material into chambers;
• a sealing mechanism that includes:
• an isolation element disposed having an isolation surface that supports the plies,
• a heating assembly defining a guide surface operable to heat the plies at a location that is transversely adjacent to the isolation surface to create a longitudinal heat seal that seals the first and second plies together to seal the fluid in the chambers as the web material is driven over the guide surface in a downstream direction, and
• a compression element held against the isolation surface that applies pressure to the web material against the isolation surface,
• wherein the isolation surface has a first radius and the guide surface has a second radius smaller than the first radius such that the isolation and guide surfaces have different curvatures and the curvatures of the isolation surface and the guide surface curve in a same direction, thereby forming a complex bend in the plies in a transition region disposed transversely between the guide and isolation surfaces, the complex bend including a longitudinal curve and a transverse curve;
• wherein the isolation element extends into the compression element and applies pressure to the compression element via the isolation surface such that the complex bend isolates the fluid in the chambers from the longitudinal heat seal during the creation of the longitudinal heat seal, the pressure applied by the isolation surface to the compression element being greater than that applied by the guide surface to the compression element;
• and
• a driving mechanism that drives the plies in the downstream direction over the guide surface, the isolation surface and through the transition region from an upstream location to a downstream location.