Patent ID: 8579877

Claim:
An intravenous (IV) bag for use in medical practices, comprising: a bladder containing a first substance; and a storage cap containing a second substance sealed to the IV bag, said storage cap positoned to release the second substance into the bladder to mix with the first substance without exposing the first substance to outside contamination, the storage cap comprising: a first structure having a first wall at least partially defining an inner storage chamber operable for storing the second substance, the first wall also defining a first annular opening having a first annular convex surface facing toward the storage chamber; and a second structure coupled to the first structure, the second structure including a plunger element located within the storage chamber and having a domed-end with a convex surface facing toward the annular opening, the domed-end having a radius greater than one-half of the diameter of the first opening; wherein the second structure is configured such that the domed end is moveable to make and break contact with the annular opening, and wherein when the domed end is in contact with the first annular convex surface, a seal is formed between the two convex surfaces along an annular path to seal the storage chamber.