The present invention relates to an annular barrier to be expanded in an annulus between a well tubular structure and a wall of a borehole downhole for providing zone isolation between a first zone having a first pressure and a second zone, the annular barrier comprising a tubular metal part for mounting as part of the well tubular structure, the tubular metal part having a first expansion opening, an axial extension and an outer face, an expandable sleeve surrounding the tubular metal part and having an inner face facing the tubular metal part and an outer face facing the wall of the borehole, each end of the expandable sleeve being connected with the tubular metal part, and an annular space between the inner face of the expandable sleeve and the tubular metal part, the annular space having a space pressure, wherein fluid inside the tubular metal part has a tubular pressure, and wherein the annular barrier comprises an expansion unit having a first inlet in fluid communication with the expansion opening, a second inlet in fluid communication with the first zone and an outlet in fluid communication with the annular space, and the expansion unit comprising an element movable at least between a first position and a second position, in the first position the expansion opening being in fluid communication with the outlet and the tubular pressure being higher than the first pressure, and in the second position the outlet being in fluid communication with the first zone and the first pressure being higher than the tubular pressure, wherein the tubular metal part comprises at least one second expansion opening being fluidly connected with the first inlet. The present invention also relates to a downhole system.
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