I only used vacuum pumps in two cases.
in the first to make the void in the rooms where there were some details that were filled in helium.
in the second applied to die casting molds to improve mold filling.
this last application has had a strong evolution, so that now you also make some frame details for motorcycles and components for motor cars.
Hi.
I used vacuum pumps in furnaces that work at high temperature, there are classic mechanics or for more pressed voids use diffusers (oil bath).
suction turbines in theory are used in powder treatment should have nothing other than the classic fan I'm not sure but logic rigor, see it as a contrery blower instead of using the suction.
of the first 3 rows are certain of the other 3 I go to logic but could be wrong
another application of the vacuum pump I saw it in a waste water distiller, served to evaporate, quickly, the waters so as to divide them from the oils.
in reference to helium seal tests, the pumps used for high vacuum were roots, with lobes impellers, such as those of volumetric compressors mounted on cars.