Quick and safe connection of hose assemblies and loading arms to mobile and stationary tanks,under pressure and with minimized liquid loss. Both coupling parts are equipped with a flat poppet valve for the connection, the hose unit is pushed onto the tank unit and coupled sealed by turning the coupler clockwise by 15 degrees.When the unit is turned by 100 degrees, the valves move into the tank unit so that the medium can flow.When a similar turn is made counterclockwise, the flow is stopped and the coupler can be pulled off.