A process for continuously producing a pulp biomass, comprising subjecting a biomass containing feed to a treatment which comprises bringing the feed to a pressure of 100-250 bar, keeping the pressurized feed subsequently or concomitantly at a temperature not exceeding 280 degrees C. A downhole deployment valve may provide the isolation utilizing a valve member such as a flapper that is disposed in a housing of the DDV and is designed to close against a seat within the housing. The N bits are interleaved and error-correction encoded to generate parity bits corresponding to an EC codeword. An output 3 is used for supplying questions to a user. The filter element fits into the body part of the housing, and the end cap and the body part have interengaging formations in the form of at least one rib and at least one groove, arranged so that the rib can be slid into the groove when the filter element is fitted into the body part, and so that the filter element rotates with the body part relative to the head part. The housing supports act to provide additional structural support for the top and bottom walls of the linear housing.