A device for changing a flow of a bulk material flowing through a flexible tube, in accordance with the intended use, the device comprising: - an attachment means (5, 5') for attaching the flexible tube; and - a deforming means arranged and operable to deform the flexible tube radially to a longitudinal axis to change the flow of the bulk material flowing in a direction of the longitudinal axis of the flexible tube; wherein the attachment means (5, 5') includes an adjustable clamping member which is adapted for encircling the flexible tube about the longitudinal axis and which has an aperture extending radially with respect to the longitudinal axis; and wherein by adjusting the clamping member, the flexible tube (i) can be pressed against a surface defining an opening of the device in a sealing manner such that the flow of the bulk material can pass through the opening, and (ii) can subsequently be released from the opening by readjusting the clamping member; and after detaching the flexible tube from the surface, the flexible tube can be removed by pulling it radially to the longitudinal axis through the aperture, wherein the attachment means (5, 5') includes a carrier ring which surrounds the flexible tube and to which the flexible tube is attachable and against which the clamping element bears, preferably directly; and the clamping member can press the flexible tube against the surface via the carrier ring during the adjustment, and wherein the flexible tube can be wrapped over the carrier ring in such a way that an end face of the carrier ring facing in the direction of the surface can bear against the flexible tube; and the clamping member bears, preferably directly, against an end face of the carrier ring opposite the end face; and the clamping member acts on the carrier ring during adjustment in such a way that the end face can press the flexible tube against the surface. - an attachment means (5, 5') for attaching the flexible tube; and - a deforming means arranged and operable to deform the flexible tube radially to a longitudinal axis to change the flow of the bulk material flowing in a direction of the longitudinal axis of the flexible tube; wherein the attachment means (5, 5') includes an adjustable clamping member which is adapted for encircling the flexible tube about the longitudinal axis and which has an aperture extending radially with respect to the longitudinal axis; and wherein by adjusting the clamping member, the flexible tube (i) can be pressed against a surface defining an opening of the device in a sealing manner such that the flow of the bulk material can pass through the opening, and (ii) can subsequently be released from the opening by readjusting the clamping member; and after detaching the flexible tube from the surface, the flexible tube can be removed by pulling it radially to the longitudinal axis through the aperture, wherein the attachment means (5, 5') includes a carrier ring which surrounds the flexible tube and to which the flexible tube is attachable and against which the clamping element bears, preferably directly; and the clamping member can press the flexible tube against the surface via the carrier ring during the adjustment, and wherein the flexible tube can be wrapped over the carrier ring in such a way that an end face of the carrier ring facing in the direction of the surface can bear against the flexible tube; and the clamping member bears, preferably directly, against an end face of the carrier ring opposite the end face; and the clamping member acts on the carrier ring during adjustment in such a way that the end face can press the flexible tube against the surface. wherein the attachment means (5, 5') includes an adjustable clamping member which is adapted for encircling the flexible tube about the longitudinal axis and which has an aperture extending radially with respect to the longitudinal axis; and wherein by adjusting the clamping member, the flexible tube (i) can be pressed against a surface defining an opening of the device in a sealing manner such that the flow of the bulk material can pass through the opening, and (ii) can subsequently be released from the opening by readjusting the clamping member; and after detaching the flexible tube from the surface, the flexible tube can be removed by pulling it radially to the longitudinal axis through the aperture, wherein the attachment means (5, 5') includes a carrier ring which surrounds the flexible tube and to which the flexible tube is attachable and against which the clamping element bears, preferably directly; and the clamping member can press the flexible tube against the surface via the carrier ring during the adjustment, and wherein the flexible tube can be wrapped over the carrier ring in such a way that an end face of the carrier ring facing in the direction of the surface can bear against the flexible tube; and the clamping member bears, preferably directly, against an end face of the carrier ring opposite the end face; and the clamping member acts on the carrier ring during adjustment in such a way that the end face can press the flexible tube against the surface.