{HEAD ~ an extrusion bowl} comprising a sleeve element fixed at the central portion of said conical part of the cover, {TAIL ~ a portion} of said sleeve element extending inside said vessel and an aperture longitudinally provided in said portion, 
comprising
{ HEAD ~ an extrusion bowl } comprising a sleeve element fixed at the central portion of said conical part of the cover , { TAIL ~ a portion } of said sleeve element extending inside said vessel and an aperture longitudinally provided in said portion ,
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH