Bypass vented extruder

Another method to control the flow rate into the extraction section is to use a bypass system. This system was proposed by Willert of Egan Machinery Company [14]. Maddock and Matzuk [15] discussed the principles of the bypass vented extruder and described actual experiments with different screw geometries. The bypass vented extruder is shown schematically in Fig. 8.42. 

FIGURE 2.21 A two-stage vented extruder with a valved bypass. (After Fisher, E. G. 1971. Blow Molding of Plastics. Iliffe, London.)... 

FIGURE 14.2 A two-stage vented extruder in which a valved bypass section steps down the pressure developed in the first stage to atmospheric pressure for venting valve is for adjustment. (Data from Van Ness, R. I. et ah, Mod. Plast., 45, 672, October 1968.)... 

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