flocks which may occasionally form inside the pump and which are harmful to the pumping process it is also possible to feed liquid discharged from the pulp to a container for temporary storage from which the liquid may be fed back to dilute occasional consistency peaks or pulp flocks in the pump as for example at or around area 62 or adjacent the pump which flocks may otherwise impair the trouble free pumping operation it will be appreciated that it is not necessary to feed the liquid separated from one or more of the filter surfaces to only one location within the system but it is possible to direct the liquid at the same time to many different points within the pumping process as needed none of the above figures show a device for withdrawing the internal dilution liquid filtered from the pulp because no device such as a pump is needed if the filter surfaces are located on the discharge side in a pressurized chamber since the liquid flows by itself due to the pressure created by the height of the pulp in the mass tower and the pressure generated by the pump on the other hand if the dilution liquid is taken from the filter surface on the suction side a pump may be necessary to convey the liquid to the pulp vessel.