Devices and systems for capturing and removing accumulated gas bubbles in a liquid-carrying line wherein the device is an expanded double-layered chamber designed and adapted to be integrally placed within the flow pathway of a liquid-carrying line. The device allows insertion of tubes and wires through the device while in use without occlusion of the fluid flow path and without interruption of the bubble-removing function. The efficiency of the air venting and bubble-removing process is not dependent on the fluid flow rate under stable flow conditions, and the device works to remove air bubbles under a range of orientations.