Patent ID: 8608723

Claim:
A fluid transfer device for use with a medicinal vial having a longitudinal vial axis and including a vial body having a vial interior for storing a medicament, a vial rim defining a vial opening, a narrow neck intermediate the vial body and the vial rim, a vial stopper sealing the vial opening and having a stopper thickness T close to the vial axis, the vial stopper having an uppermost stopper surface, the fluid transfer device comprising: a) a vial adapter having a longitudinal adapter axis and including a top wall transverse to said adapter axis, a downward depending skirt with flex members configured to be snap fitted onto the vial rim for concentric mounting of said vial adapter on the vial, a tubular cannula having a pointed tip configured to initially contact the vial stopper at a puncture site and puncture therethrough for establishing flow communication with the vial interior on said snap fit mounting, and a flow communication channel in flow communication with said cannula; and b) an elastic O-ring like sealing element sealingly encircling said cannula and being slidably disposed on said cannula, said sealing element being initially disposed along said cannula and spaced apart from said top wall and said pointed tip to leave a first exposed cannula length L between said sealing element and said pointed tip and a second exposed cannula length between said sealing element and said top wall, said first exposed cannula length L being shorter than said stopper thickness T such that said sealing element contacts the vial stopper prior to said cannula puncturing therethrough, said sealing element being configured to be brought into initial contact with the vial stopper subsequent to said pointed tip contacting the vial stopper at said puncture site and to be thereafter slidingly urged on said cannula toward said top wall and continuously seal said puncture site during said snap fit mounting of said vial adapter on the vial.