One embodiment of a blood transfusion device includes a drip chamber (10) comprising a bottom outlet (113) a filter (40) fixedly disposed in the drip chamber (10) and a float regulator (20) moveably disposed in the drip chamber (10) under the filter (40). the float regulator (20) comprising an inverted upper cup (21) including a top projection (212), a lower cup (22) secured to the upper cup (21), and a suction cup (23) secured to an underside of the lower cup (22). An inner diameter of the upper cup (21) is greater than an outer diameter of the lower cup (22). The projection (212) contacts an underside of the filter (40) when blood from a blood bag (90) sufficiently fills the drip chamber (10). The suction cup (23) falls to permanently close the outlet (113) when blood in the drip chamber (10) completely drains.
