A milk flow device which includes a conduit for transporting a substantially continuous milk flow varying in height up to a maximum height wherein the maximum height is less than a fluid height which would occlude the conduit and interrupt the vacuum level is shown. A first sensor determines the height of a selected section of the substantially continuous milk flow. The first sensor has a predetermined cross-sectional area and defines an opening for passing a milk flow therethrough. The first sensor is located at a predetermined location in the conduit. A second sensor having a cross-sectional area substantially equal to the cross sectional area of the first sensor is spaced within the conduit in a selected direction and a known distance from the first sensor. The second sensor determines that the selected section of the continuous milk flow has traversed the known distance. A conductivity sensor measures the conductivity of the milk. A processing device derives the cross-sectional area of a milk flow from the height of the selected section of the milk flow, determines the elapsed time for the selected section of the milk flow to traverse the known distance and calculates milk flow through the conduit.