Abstract: The present invention relates to a pressure control system for maintaining the pressure differential between a reactor (1) and a feeder (2) connected thereto and provided for introducing feed into the reactor (1), characterized in that the pressure control system comprises a pressure up line (5) and a pressure release line (6), each line (5, 6) having a control valve (7, 8), both lines (5, 6) combining into one main line (3) leading to the feeder (2), wherein a filter unit (4) is provided in the main line (3); as well as to a reactor having such a pressure control system and a process utilizing a reactor with the specific pressure control system.