Pumping Instability
Vol. 33 #1, Summer 2006
Product rate variability in a single screw extruder is often caused by pumping instabilities in the feed and transition sections. The screw can be analyzed by monitoring the pressure variability. Installing a pressure tap in the early sections (zone 1) is helpful. A read rate of 30 reads/sec is needed. Pressure fluctuations of less than 2.5% are generally OK. If adjusting the temperature profile in zone 1 does not reduce the pressure variation, then a new screw design may be needed.
– Barry Morris, DuPont
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