the inner surface 58 and outer surface 60 of the plate the lower side surface 64 of each slot 52 may form an inclination angle u03c9 of between zero to 15 degrees and preferably 5 to 15 degrees with respect to horizontal this inclination angle causes the cross section of the lower side surface to be parallel to horizontal or have an upward incline with respect to the inside surface 58 of the plate the lower side surface with a horizontal or inclined slope tends to deflect chips that are drawn into the slot back into the pulp flow f and away from the slot the slope of the lower side surface is inward on the plate of the curved inlet 64 the combination of the curved inlet and horizontal or inclined lower side enhances the ability of the slots 52 to deflect chips into the pulp flow and avoid clogging the slots 52 in the plate 50 have an expanding opening with an opening angle u03b2 that facilitates the movement of liquor fl through the slot and the screen plate in view of the slope of the lower side surface 62 the opening angle as indicated by the angle of arrow fl is offset at an upward incline equal to the sum of one half the opening angle u03b2 and the inclination angle u03c9 of the lower side of the slot the offset upward opening angle results in.