The invention relates to a valve (10, 110) having a valve chamber (14, 114), having at least one inlet conduit (16, 116) and one outlet conduit (18, 118), furthermore having a movable lifting rod (34, 134), one end of which opens into an actuator (53), and having at least one valve member (36, 136, 236) secured to the lifting rod (34, 134), and having at least one valve seat (22, 122) cooperating with the valve member (36, 136, 236).It is proposed that the valve seat (22, 122) and / or valve member (36, 136, 236) is elastically deformable in such a way that the elasticity of the valve seat (22, 122) and / or valve member (36, 136, 236) is at least so great that the valve member (36, 136, 236) can be thrust through the valve seat (22, 122) by an in particular external exertion of force and that the valve seat (36, 136, 236) and the valve member (22, 122) return to their outset state.