TUBE NEWS 2016 November 2016 | Page 9

inlet has been redesigned and the effective inlet area enlarged. As a result of this redesign, the maximum feeding capacity and throughput has been increased. An increase of up to 15% is possible, especially for smaller sizes. This increase in capacity is achieved with keeping consistently good operating conditions (minimum number of cut grains and smooth running). Also the noise caused by leakage gas expansion, which is the main source of noise in high-pressure rotary valves (up to 3.5 bar differential pressure), has been reduced considerably by a new design of the expansion opening. Furthermore, the transformation of the elongated opening to a pipe connection was integrated in the cast. An additional consequence of the reduction in noise emission is that an adapter piece is no longer required. The ZV valve also now has a pipe connection that meets the standard. The Finite Element Method (FEM) was used to calculate the cast housing, which optimized its rigidity while reducing the mass at the same time. This allows a narrow gap between the rotary valve and the housing, with the advantage of a low gas leakage rate when operating the new ZV pellet rotary valve. 9 TN November 2016