outlet of the feed pump p 1 which is within 10 of the entire length of the feed line 10 during normal disturbance free operation in the system the fall in pressure in the feed line 10 between the points 10 a and 10 b should expediently exceed or correspond to the increased pressure in the washing liquid filtrate 13 a 13 b in the embodiment shown the diffuser washing device consists of two diffusers which are coupled in parallel as regards the receipt and treatment of cooked pulp obtained from the digester this configuration provides increased availability in the system with it being possible to redirect part of the pulp flow between diffusers depending on any possible momentary disturbances in the system the diffuser pump arrangement consists of two diffuser pumps p 2 a and p 2 b which are coupled in parallel and which on the inlet side are connected to the same supply flow 11 which is taken from the main feed line 10 with each respective outlet from each of the diffuser pumps only supplying one diffuser with its respective washing liquid flow 12 a 12 b while p 2 a and p 2 b can of course be replaced with a single pump two separate pumps provide increased availability the wash filtrates 13 a and 13 b which are obtained from each respective diffuser are first of all combined to form a joint flow 16 in a y coupling after which this combined wash filtrate flow 16 is returned to the main feed line at a point 10 b on the main feed line closer to the inlet to the digester pump p 3 the whole of the system becomes self adjusting with regard to any possible.