diameter b which is of different size than the diameter a and is shown in the drawings as being smaller a flange 20 of the insert 19b limits its insertion into the boss the operator can selectively choose the insert 19a or 19b to change the effective size of the stock entry opening which leads tangentially into the chamber 13 the plurality of inserts can also be used to provide a plurality of inlet configurations thus by changing inserts the inlet design can be changed from cylindrical to conical or even rectangular the upper end of the chamber 13 is provided with an annular boss 16 adapted to receive an insert 23a the insert 23a has a flange 25 at its upper end to fit snugly into the boss 16 and has a central overflow or vortex finder opening 24 of a diameter c a plurality of vortex finder inserts are provided with another being illustrated in fig4 and 5 at 23b these are provided with flanges 25 and have a flow opening 24 therethrough of a diameter d which is shown to be smaller than the diameter c of the insert 23a the operator can remove the inset 23a and substitute therefor the inset 23b to obtain a smaller vortex finder opening it will be seen that by providing a plurality of inserts such as 23a and 23b for the vortex finder opening different sizes of opening from the chamber 13 can be achieved also by having a plurality of inserts such as 19a and 19b the operator can selectively choose the inlet flow opening by changing these openings selectively the operator has the capability to adjust either the capacity of cleaning efficiency without.