METHOD OF PREVENTING CLOGGING A SCREENING MEANS

摘要

In screening a fibre suspension, an accept and a reject are tapped off, tapping the reject being controlled by a valve (6). According to the invention, the pressure drop across the screening means is measured, and when this drop exceeds a predetermined first value the valve (6) is opened from a first to a second position and when the pressure drop falls below a second predetermined value or when a given predetermined time has passed the valve is returned to its position prior to opening. In this second position the reject valve (6) is preferably completely open. The accept flow may possibly also be constricted when the reject valve is in the second position.