A volumetric pump including a housing, a front flap having a locking lever to be operated manually, and a sensor system with contactless sensors for the volumetric pump operating according to the linear peristalsis principle, which detects the position of a front flap and/or the locking lever relative to the housing of the volumetric pump, the sensor system comprising: at least one sensor unit; at least one sensor transmitter unit; and a sensor output signal processing unit, wherein the sensor transmitter unit is arranged to apply a detection variable varying as a function of a travel position to the sensor unit along a predetermined travel along which a fixedly arranged sensor unit preferably mounted on the housing and a movably arranged sensor transmitter unit are moving relative to each other, the sensor unit is configured to output, on the basis of the varying detection variable, a detection signal corresponding to the respective travel position, the sensor output signal processing unit is arranged to receive the detection signal output by the sensor unit and to discriminate at least three travel positions on the basis of the received detection signal, wherein the at least three travel positions comprise a closed position in which a tube portion inserted in the pump is occluded, an open position in which the tube portion inserted in the pump is not occluded and an intermediate position provided between the closed position and the open position, and the sensor transmitter unit is mounted on a locking bar mechanically controlled in its position by a locking lever. a front flap having a locking lever to be operated manually, and a sensor system with contactless sensors for the volumetric pump operating according to the linear peristalsis principle, which detects the position of a front flap and/or the locking lever relative to the housing of the volumetric pump, the sensor system comprising: at least one sensor unit; at least one sensor transmitter unit; and a sensor output signal processing unit, wherein the sensor transmitter unit is arranged to apply a detection variable varying as a function of a travel position to the sensor unit along a predetermined travel along which a fixedly arranged sensor unit preferably mounted on the housing and a movably arranged sensor transmitter unit are moving relative to each other, the sensor unit is configured to output, on the basis of the varying detection variable, a detection signal corresponding to the respective travel position, the sensor output signal processing unit is arranged to receive the detection signal output by the sensor unit and to discriminate at least three travel positions on the basis of the received detection signal, wherein the at least three travel positions comprise a closed position in which a tube portion inserted in the pump is occluded, an open position in which the tube portion inserted in the pump is not occluded and an intermediate position provided between the closed position and the open position, and the sensor transmitter unit is mounted on a locking bar mechanically controlled in its position by a locking lever. at least one sensor unit; at least one sensor transmitter unit; and a sensor output signal processing unit, wherein the sensor transmitter unit is arranged to apply a detection variable varying as a function of a travel position to the sensor unit along a predetermined travel along which a fixedly arranged sensor unit preferably mounted on the housing and a movably arranged sensor transmitter unit are moving relative to each other, the sensor unit is configured to output, on the basis of the varying detection variable, a detection signal corresponding to the respective travel position, the sensor output signal processing unit is arranged to receive the detection signal output by the sensor unit and to discriminate at least three travel positions on the basis of the received detection signal, wherein the at least three travel positions comprise a closed position in which a tube portion inserted in the pump is occluded, an open position in which the tube portion inserted in the pump is not occluded and an intermediate position provided between the closed position and the open position, and the sensor transmitter unit is mounted on a locking bar mechanically controlled in its position by a locking lever.