An apparatus for connecting multi-lumen conduits may include a conduit adapter and a conduit collar. The apparatus comprises an airlock containing a fluid for sealing the vessel and an electrical circuit operatively arranged to pass a current through the fluid to detect passage of bubbles through the airlock. Ink particles and bubbles flowing from the ink reservoir to the printhead are filtered out, bubbles which may flow from the printhead to the ink reservoir, move to edges of the filter, and the ink is smoothly supplied to the printhead. The clipping device includes a pair of clips, a supporting plate and a circuit board cover to securely hold the circuit board.