METHOD AND APPARATUS IN SCREENING FIBRE SUSPENSIONS
Method and apparatus in screening a fibre suspension in a pressure screen (10) with an inlet (1) for the fibre suspension and outlets (2, 3) for accept and reject, respectively, a conduit (12, 13) being respectively connected to said outlets, the reject conduit (13) opening to the atmosphere at its end facing away from the reject outlet and being at least partially at a higher level than both inlet (1) and reject outlet (3), the flow through said conduit (13) being measured, the difference between the measured value and a criterion value being determined, and the flow through the reject conduit (13) being changed in response to a function of the difference of the change of the flow through the accept conduit (12) by means of a valve (7) in said accept conduit (12).