a sleeve 56 acts as an abutment which sleeve 56 is formed at the cover 37 of the valve cap 30 and projects into the inner space of valve cap 30 this flushing valve 15 allows now two flushing modes i e it allows a controlling of the amount of flushing water in two steps the partial flushing mode is initiated by pressing lever 16 downwards by a relatively small amount the corresponding short axial movement of the piston rod 25 leads to a lifting off of the sealing rod sleeve 31 from the o ring 44 whereby the sealing rod sleeve 31 does not reach the abutment position in which it contacts sleeve 56 accordingly water is free to flow through the through bores 42 of the side wall 41 of the valve cap 30 through the central opening 46 as well as the openings 35 of the partition 26 thereby the forces of both compressed springs 43 and 54 pressure prevailing in the upper chamber 27 as well as a flow pressure act combined on the sealing rod sleeve 31 these pressure forces hold this sealing rod sleeve 31 against the combined forces of springs 43 and 54 in its open position until the pressure vessel 2 has been emptied by a certain amount and the pressure has fallen accordingly thereafter the sealing rod sleeve 31 is reset by the pressure spring 43 and by the resetting spring 54 such to move again in its sealing position the complete.