In the forming section of a paper machine, a large amount of water is removed from the wet paper web in a very short period of time. At the end of the forming section suction boxes remove water by applying a local vacuum: the pressure drop causes water to flow out of the web and into the suction box.

 

Innventia has designed a laboratory scale suction box to study the dewatering and deformation behaviour of fibre mats during and after a suction pulse. The mechanics and instrumentation of the laboratory suction box are designed to account for all mechanisms that determine the final dry content of the web after suction pulse:

 

 

In the Innventia laboratory suction box we can controll the duration of the pressure pulses (50 ms to 10 s) and the vacuum applied to the suction box (0 to -40 kPa). The thickness of the paper web is monitored continuosly during the suction pulse and directly afterwards. Additionally the laboratory set up allows for studies of rewetting since it is equipped with a separation device that can remove the web from the suction box at defined times during and after the suction pulse.