An infusion system configured to automatically control an infusion pump, the infusion system comprising: an infusion pump configured to pump an infusion fluid along a flow path; a first acoustic sensor positioned at a first location along the flow path, the first acoustic sensor configured to detect a first acoustic signal; a second acoustic sensor positioned at a second location downstream from the first acoustic sensor along the flow path, the second acoustic sensor configured to detect a second acoustic signal; wherein the first acoustic signal is emitted from the second acoustic sensor parallel to the flow path and the second acoustic signal is emitted from the first acoustic sensor parallel to the flow path, and a controller configured to: determine a first volumetric flow rate of the infusion fluid based on the detected first acoustic signal and the detected second acoustic signal, and adjust the infusion pump based on the detected first volumetric flow rate to achieve a desired volumetric flow rate, wherein the first volumetric flow rate is determined based on; measuring a phase angle between the emitted first acoustic signal and the detected first acoustic signal by a phase discriminator to determine a first phase delay of the first acoustic signal, between the first acoustic sensor and the second acoustic sensor; or measuring a phase angle between the emitted second acoustic signal and the detected second acoustic signal by a phase discriminator to determine a second phase delay of the second acoustic signal, between the second acoustic sensor and the first acoustic sensor. an infusion pump configured to pump an infusion fluid along a flow path; a first acoustic sensor positioned at a first location along the flow path, the first acoustic sensor configured to detect a first acoustic signal; a second acoustic sensor positioned at a second location downstream from the first acoustic sensor along the flow path, the second acoustic sensor configured to detect a second acoustic signal; wherein the first acoustic signal is emitted from the second acoustic sensor parallel to the flow path and the second acoustic signal is emitted from the first acoustic sensor parallel to the flow path, and a controller configured to: determine a first volumetric flow rate of the infusion fluid based on the detected first acoustic signal and the detected second acoustic signal, and adjust the infusion pump based on the detected first volumetric flow rate to achieve a desired volumetric flow rate, wherein the first volumetric flow rate is determined based on; measuring a phase angle between the emitted first acoustic signal and the detected first acoustic signal by a phase discriminator to determine a first phase delay of the first acoustic signal, between the first acoustic sensor and the second acoustic sensor; or measuring a phase angle between the emitted second acoustic signal and the detected second acoustic signal by a phase discriminator to determine a second phase delay of the second acoustic signal, between the second acoustic sensor and the first acoustic sensor. measuring a phase angle between the emitted first acoustic signal and the detected first acoustic signal by a phase discriminator to determine a first phase delay of the first acoustic signal, between the first acoustic sensor and the second acoustic sensor; or measuring a phase angle between the emitted second acoustic signal and the detected second acoustic signal by a phase discriminator to determine a second phase delay of the second acoustic signal, between the second acoustic sensor and the first acoustic sensor.