Apparatus and method for attaching a tap to a mounting surface (13) has a clamping assembly inserted through an aperture (11) in the mounting surface (13) and tightened from above the mounting surface (13). The clamping assembly has a pair of clamping arms (25, 27) that are mounted for pivotal movement from a collapsed position for passage through the aperture (11) to an operative position below the mounting surface (11). The clamping arms (25, 27) are operable on tightening the clamping assembly to engage in a first stage an underside of the mounting surface (13) remote from the fluid delivery device and to engage in a second stage a sidewall of the aperture (11) when continuing tightening. Thus a step change in an operating force is required that provides feedback to an installer that a required clamping force has been achieved.