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