A tank (500") with a door locking mechanism comprising: (a) said tank (500") comprising a housing having an interior cavity for receiving an expandable bioprocessing container having flexible walls; a bottom wall; a side wall (509"), wherein the side wall (509") has an opening (509A"); an outwardly pivoting tank door (510"); and a hinge mounted to the side wall (509") and the outwardly pivoting tank door (510"), wherein the outwardly pivoting tank door (510") is arranged to cover at least a portion of the opening (509A"); the tank (500") including a door locking mechanism comprising: (i) a rotatable shaft mounted to the outwardly pivoting tank door (510"), the rotatable shaft having a first end and a second end, the second end comprising a projecting arm; and, (ii) an arm receiver, comprising a base mounted to the at least one side wall (509") of the tank (500") at a distance from the outwardly pivoting tank door (510") and the rotatable shaft, the arm receiver further comprising a receiver top extending horizontally from the base, the receiver top comprising a receiver top wall, first and second opposing receiver top side walls (283, 284), a receiver top rear wall, and a receiver top front wall having a bottom end, the receiver top opposing side walls (283, 284) each extending toward the base a distance past the bottom end of the receiver top front wall; the bottom end of the receiver top front wall and first and second opposing receiver top side walls (283, 284) defining an arm receiver opening for receiving the projecting arm when the rotatable shaft is rotated to align the projecting arm with the arm receiver opening, and the outwardly pivoting tank door (510") pivots outwardly upon being contacted by an expanded bioprocessing container. (a) said tank (500") comprising a housing having an interior cavity for receiving an expandable bioprocessing container having flexible walls; a bottom wall; a side wall (509"), wherein the side wall (509") has an opening (509A"); an outwardly pivoting tank door (510"); and a hinge mounted to the side wall (509") and the outwardly pivoting tank door (510"), wherein the outwardly pivoting tank door (510") is arranged to cover at least a portion of the opening (509A"); the tank (500") including a door locking mechanism comprising: (i) a rotatable shaft mounted to the outwardly pivoting tank door (510"), the rotatable shaft having a first end and a second end, the second end comprising a projecting arm; and, (ii) an arm receiver, comprising a base mounted to the at least one side wall (509") of the tank (500") at a distance from the outwardly pivoting tank door (510") and the rotatable shaft, the arm receiver further comprising a receiver top extending horizontally from the base, the receiver top comprising a receiver top wall, first and second opposing receiver top side walls (283, 284), a receiver top rear wall, and a receiver top front wall having a bottom end, the receiver top opposing side walls (283, 284) each extending toward the base a distance past the bottom end of the receiver top front wall; the bottom end of the receiver top front wall and first and second opposing receiver top side walls (283, 284) defining an arm receiver opening for receiving the projecting arm when the rotatable shaft is rotated to align the projecting arm with the arm receiver opening, and the outwardly pivoting tank door (510") pivots outwardly upon being contacted by an expanded bioprocessing container. (i) a rotatable shaft mounted to the outwardly pivoting tank door (510"), the rotatable shaft having a first end and a second end, the second end comprising a projecting arm; and, (ii) an arm receiver, comprising a base mounted to the at least one side wall (509") of the tank (500") at a distance from the outwardly pivoting tank door (510") and the rotatable shaft, the arm receiver further comprising a receiver top extending horizontally from the base, the receiver top comprising a receiver top wall, first and second opposing receiver top side walls (283, 284), a receiver top rear wall, and a receiver top front wall having a bottom end, the receiver top opposing side walls (283, 284) each extending toward the base a distance past the bottom end of the receiver top front wall; the bottom end of the receiver top front wall and first and second opposing receiver top side walls (283, 284) defining an arm receiver opening for receiving the projecting arm when the rotatable shaft is rotated to align the projecting arm with the arm receiver opening, and the outwardly pivoting tank door (510") pivots outwardly upon being contacted by an expanded bioprocessing container.