The innovative aspect of this design is that TDI and eventually a TDI compatible 6th component are axially fed to the mixing chamber through the small piston that cleans the mixing chamber. The other four components (polyols, other catalysts, additives, flame retardants, etc) are fed radially.
A seal on the small piston provides permanent separation between the two feeding areas so that any crossover of low viscosity components is avoided. By feeding these low-viscosity components in an axial way, it is possible to apply on them a limited dosing pressure (as low as 10-20 bar) with immediate advantages in terms of component-line simplification and safety. Fillers - such as fire-retardant mineral charges, or pulverized PU scrap foam - can be fed through this axial stream avoiding the use of abrasion-resistant mechanical parts.