fig3 with reference to fig4 a 4 b and the above description of mounting the following occurs when the thread bushing 20 is for example adjusted by an allen key in the hexagonal actuating hole 18 this can preferably occur without the actuator being mounted when the abutment means 16 is moved toward the closure element 5 a preferably uniformly distributed force is peripherally applied between the above components for mutual sealing this force is suitably transmitted centrally by the thread bushing 20 as force transmitting means this single adjusting means results in adjustment being achieved in a simple and uniform manner in the valve housing 2 the support portion 25 and the seat portion 31 act as an abutment for the closure element so that the abutment means 16 obtains the desired function in the opposite direction the coupling device 7 together with the thread bushing 20 acts as an abutment for the press fit force exerted by the abutment means 16 the abutment means 16 preferably exerts a pressure at a suitable radial distance from its centre on the closure element 5 adjacent the edge portion 26 this distance is adjusted so that the closure element 5 can flex adjacent the flexible portion 30 for actuating the valve 1 in other words the closure element has adjacent said portion 30 at the end the sealing portion 14 some freedom of movement so that the closure element can move in the intended vertical direction the abutment means 16 preferably abuts on both sides.