An intravenous infusion device (10) comprises a fluid drip chamber (11) having an inlet (12) and an outlet (13). A floating plug (14) provides an indication of fluid level and when the fluid is exhausted the plug (14) settles in the outlet (13) and, being made from a soft deformable material, effectively forms a bung preventing air entering the line (4). It is thus a simple matter to replace an associated fluid bottle (2) and allow the replenished fluid to flow with minimal interruption or intervention. By providing the plug (14) with a flexible skirt or fin (15) and providing the chamber (11) with a conical end section (16) an enhanced seal is provided by the fin (15) engaging the conical section (16). In a further enhancement the conical section (16) has an opaque lower section (17) and the plug (14) is thus obscured from view as the fluid is depleted providing an enhanced visual indication that the fluid bottle (2) is empty. The plug (14) may advantageously also be coloured at least partially green such that the presence of a green indicator indicates that the infusion device is functioning.
