Suction Couch Roll

This roll (Fig. 6.3) is placed at the end of the tvire section where the web is already formed. It further increases the density of the web and increases its dry content. A small amount of white water is removed and the operating vacuum is about 0.3 to 0.7 bar. The vacuum chamber is divided into two zones with stepvdse increase in vacuum. Shadow marking may occur on sensitive papers with too high vacuum application or inadequate drilling pattern. The open area is about 60%. 

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Fig. 6.3 Schematic of a forming roll and a suction couch roll (source Voith).

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