Abstract
The flow rate coefficient was calculated both theoretically, based on calculus relationships, and experimentally, based on data obtained on two extruders with screw diameters of 45 mm and 90 mm, respectively. The concordance of the theoretical results with those obtained experimentally in two situations were verified, namely: free discharge, no backpressure, and discharge with backpressure. Keywords: flow rate coefficient; feeding zone; single screw extruder; flow rate