@SandervG: Thank you, but I cannot find the type of stainless steel used on their website. My guess is that A2 and 303 are enough corrosion resistant, but I know that not all stainless steels are suitable for processing PVC in injection moulding.
@geert_2: Good point: the little material on the outside of the nozzle may have material degradation/corrosion. Fortunately it is normally only a little bit of material.
Does anyone know what metal is used for the fan duct? It is (a bit) magnetic, so it could be stainless? Or is it a zinc plated steel?