Method and a device for determining the mass flow rate and the presence or absence of a liquid flowing in a pipe

Abstract

A device () for determining the mass flow rate of milk turbulently flowing with air in a pipe () in pulsed milk slugs comprises sampling a signal from a microphone () of the device () indicative of sonic signals produced by the milk flow. The sampled signals are read by a microprocessor () which applies a Fast Fourier Transform to the sampled signal to produce the frequency domain of the sampled signal. The microprocessor () is configured to compute the average energy value of the sampled signal in the frequency bandwidth of 6 kHz to 15 kHz during consecutive monitoring periods. The average energy values are inserted into a calibration equation, which may be a power law equation, a polynomial equation, a logarithmic equation or any other such suitable equation in order to convert the average energy value to a mass flow rate of the milk flowing through the pipeduring that predefined monitoring period. The total mass flow of milk flowing through the pipeline () during a period from Tto Tis determined by integrating the determined mass flow rate of the milk from the time Tto the time T. Disengagement of a milking cluster from the teats of an animal as a result of kick-off during milking is also determined when the monitored signal from the microphone () transitions from the signal indicative of milk flowing in pulsed slugs to a continuous relatively high energy noise signal indicative of air being continuously drawn through the pipeline.