Abstract: A coupling device for use in a fluid system comprising a first coupler member (10) having a first valve means (14) and a second coupler member (20) having a second valve means (24), said coupling members (10, 20) being configured to cooperate with each other to provide a coupling device, each of the coupler members having means for connection to a fluid system and means for fastening the two members to each other; and said valve means (14, 24) being configured to cooperate with each other and to control fluid flow (F) through their respective coupler member. Fluid displacement means (15, 16, 17a,b, 18a,b) are arranged and configured for displacing at least a portion of fluid which is confined in the mating regions (M1, M2) between the coupler members (10, 20).