A mechanical seal assembly adapted for arrangement around a rotating shaft of a rotating device, the mechanical seal assembly comprises: a first seal ring that, in operation, is axially shiftable relative to the rotating shaft; a second seal ring that, in operation, is axially fixed relative to the rotating shaft; an annular carrier having a base and a removable end portion configured to be affixed to a housing of the rotating device, wherein the axially shiftable first seal ring is proximate and axially shiftable relative to the annular carrier in response to axial movement of the rotating shaft and the axially fixed second seal ring, and wherein the axially shiftable first seal ring has an axially shiftable seal face that interfaces with an axially fixed seal face of the axially fixed second seal ring; a biasing mechanism that urges the axially shiftable first seal ring toward the axially fixed second seal ring to engage the axially shiftable seal face to the axially fixed seal face with a closing force; and an annular flexible sealing membrane comprising: an outer portion arrangeable between the axially shiftable first seal ring and the biasing mechanism, the outer portion being axially shiftable relative to the rotating shaft; an inner portion surrounded by the outer portion and positioned between the base and the removable end portion of the annular carrier, wherein the annular flexible sealing membrane comprises a central hole formed in the inner portion and arranged to surround the shaft, the inner portion extends radially outward from the central hole, and the outer portion extends radially outward from the inner portion, wherein the annular flexible sealing membrane presents a generally dumbell-shaped cross-section, comprising the outer portion and the inner portion surrounded by the outer portion; wherein the base and the removable end portions hold the inner portion fixed relative to the annular carrier as the outer portion shifts relative to the rotating shaft. a first seal ring that, in operation, is axially shiftable relative to the rotating shaft; a second seal ring that, in operation, is axially fixed relative to the rotating shaft; an annular carrier having a base and a removable end portion configured to be affixed to a housing of the rotating device, wherein the axially shiftable first seal ring is proximate and axially shiftable relative to the annular carrier in response to axial movement of the rotating shaft and the axially fixed second seal ring, and wherein the axially shiftable first seal ring has an axially shiftable seal face that interfaces with an axially fixed seal face of the axially fixed second seal ring; a biasing mechanism that urges the axially shiftable first seal ring toward the axially fixed second seal ring to engage the axially shiftable seal face to the axially fixed seal face with a closing force; and an annular flexible sealing membrane comprising: an outer portion arrangeable between the axially shiftable first seal ring and the biasing mechanism, the outer portion being axially shiftable relative to the rotating shaft; an inner portion surrounded by the outer portion and positioned between the base and the removable end portion of the annular carrier, wherein the annular flexible sealing membrane comprises a central hole formed in the inner portion and arranged to surround the shaft, the inner portion extends radially outward from the central hole, and the outer portion extends radially outward from the inner portion, wherein the annular flexible sealing membrane presents a generally dumbell-shaped cross-section, comprising the outer portion and the inner portion surrounded by the outer portion; wherein the base and the removable end portions hold the inner portion fixed relative to the annular carrier as the outer portion shifts relative to the rotating shaft. an outer portion arrangeable between the axially shiftable first seal ring and the biasing mechanism, the outer portion being axially shiftable relative to the rotating shaft; an inner portion surrounded by the outer portion and positioned between the base and the removable end portion of the annular carrier, wherein the annular flexible sealing membrane comprises a central hole formed in the inner portion and arranged to surround the shaft, the inner portion extends radially outward from the central hole, and the outer portion extends radially outward from the inner portion, wherein the annular flexible sealing membrane presents a generally dumbell-shaped cross-section, comprising the outer portion and the inner portion surrounded by the outer portion; wherein the base and the removable end portions hold the inner portion fixed relative to the annular carrier as the outer portion shifts relative to the rotating shaft.