An apparatus for expanding plastics material parisons into plastics material containers by a liquid medium, with at least one transforming station which fills and expands the plastics material parisons with the liquid medium, with at least one common delivery device which delivers the liquid medium to the at least one transforming station, wherein the at least one transforming station has a filling device which fills the liquid medium into the plastics material parisons, wherein the at least one transforming station and/or the filling device has a throttle device which is suitable and intended for changing the volume flow of the liquid entering the plastics material parisons, and
- wherein the apparatus has a first sensor device which detects a measured value which is characteristic for the through flow of the liquid through the filling device, wherein the characteristic measured value is a characteristic measured value for a flow cross-section and/or a flow rate, wherein changing the volume flow includes an actual change to the product stream entering the plastics material parisons, wherein the change to the product stream entering the plastics material parisons is achieved by the throttle device having a cover element, wherein an entry of the liquid medium into the plastics material parison can be influenced by a movement of the cover element and the cover element can move to any position between two predetermined end positions to change the flow volume and/or the flow rate in a continuously variable manner.