Coupling element and coupling system for a closed fluid transfer system

A coupling member for a closed fluid transfer system, the coupling member comprising:

• A) a coupling member housing comprising a fluid connection and a coupling side, wherein a longitudinal axis of the coupling member housing extends from the fluid connection to the coupling side;
• B) a first fluid channel extending in parallel to the longitudinal axis of the coupling member housing from the fluid connection toward the coupling side to a fluid channel opening facing perpendicular to the longitudinal axis of the coupling member, for fluidly connecting the fluid connection and the coupling side;
• C) at least one elastomer member, which:
• i) surrounds the fluid channel opening of the first fluid channel;
• or
• ii) forms a second fluid channel adjoining the fluid channel opening of the first fluid channel, wherein an elastomer member opening of the second fluid channel faces perpendicular to the longitudinal axis of the coupling member housing;
• and
• D) a sealing member having a sealing surface facing the fluid channel opening of the first fluid channel or the elastomer member opening of the second fluid channel,
• wherein the sealing surface is movable along the longitudinal axis of the coupling member housing between a first position, in which the sealing surface seals the fluid channel opening of the first fluid channel or the elastomer member opening of the second fluid channel, and a second position, in which the sealing surface exposes the fluid channel opening of the first fluid channel or the elastomer member opening of the second fluid channel for fluid communication with the coupling side,
• wherein the coupling member housing comprises on an inner surface of the coupling member housing an undercut, and
• wherein the coupling member housing comprises on the coupling side a radial projection with respect to the longitudinal axis, which forms a coupling side stop for the sealing member in the first position, and wherein the undercut is formed by the radial projection.