To conclude this outline of possible applications, it is important to mention two recent uses: the maintenance of vacuum in test rooms for the simulation of flights at high altitudes - as well as in the space - and the degassing of moulded steel during casting operations in steel mills.

In these cases, the residual pressures on suction are lower than 1 mbar and the quantities of intaken fluid are considerable. This involves the setting up of huge plants with suction ducts having a diameter up to 3 m.s.