Select each Sub-mesh one by one in your inlet part (region1 and export them. Navigate to the upper menu File > Export > STL File (see figure ).
Repeat the surface mesh generation and STL export also for outlet region region2.
Repeat the surface mesh generation and STL export also for all three valve plugs. A valve plug is not split into groups so it is not necessary to create a sub-mesh. Just export the whole surface mesh of the plug.
Save your progress.
BTW: The current state can be loaded anytime as an original file: “part5.hdf“.