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