full then the baffle boards 72 in the chute assembly 70 are turned into such new positions that the wet pulp fibers 18 are directed from the thickening apparatus 60 into the chute feeding pressure chamber 16 once the pressure chamber 14 has been filled with wet pulp fibers 18 then its wet fiber filling valve 28 and air bleed valve 30 are closed pressurizing valve 32 is opened to raise the pressure in the pressure chamber 14 to the same operating pressure that is in the pressurized flow chamber 24 this completes the pressurizing phase and the pressure chamber 14 is now ready for the next emptying phase once the pressure chamber 12 is full with wet pulp fibers 18 it will be pressurized with compressed air from accumulator 20 pressurizing does not take as much time as the filling so emptying the pressure chamber 12 will start while pressure chamber 14 is still being filled by the time pressure chamber 12 is empty pressure chamber 14 has already been filled and pressurized and is ready for emptying again by the time pressure chamber 14 is empty pressure chamber 16 has been filled and pressurized and is ready for emptying this emptying sequence.