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

A method for detecting one or more properties of milk flowing turbulently in a pipeline with a gaseous phase medium as a pulsed flow comprising a plurality of time spaced apart slugs of milk with air interspersed therebetween, the one or more of the properties of the milk to be detected comprising the presence of milk flowing in the pipeline, the absence of milk flowing in the pipeline, connection of teat cups of a milking cluster to the teats of an animal, disconnection of the teat cups of a milking cluster from the teats of an animal, the commencement of milk flowing in the pipeline, and the ceasing of milk to flow in the pipeline, the method comprising:

• monitoring a sonic signal produced by the turbulently flowing spaced apart milk slugs in the pipeline,
• filtering the frequency domain of the monitored signal to produce a portion of the monitored signal within a predefined frequency bandwidth indicative of milk flowing in the pipeline, computing an energy parameter value of the portion of the monitored signal within the predefined frequency bandwidth,
• comparing the computed energy parameter value with a first predefined energy parameter value indicative of air being drawn under vacuum into the pipeline through the teat cups,
• comparing the computed energy parameter value with a second predefined energy parameter value indicative of the teat cups of the milking cluster being attached to the teats of the animal without milk flowing in the pipeline,
• comparing the computed energy parameter value with an upper third predefined energy parameter value and a lower third predefined energy parameter value indicative of milk flowing in the pipeline, and
• determining one or more of the following:
• the presence of milk flowing in a pipeline in response to the computed energy parameter value being within the upper and lower third predefined energy parameter values,
• the absence of milk flowing in the pipeline in response to the computed energy parameter value being less than the second predefined energy parameter value,
• disconnection of the teat cups of a milking cluster from the teats of an animal in response to the computed energy parameter value exceeding the first predefined energy parameter value,
• connection of teat cups of a milking cluster to the teats of an animal in response to the computed energy parameter value transitioning from a value indicative of air being drawn into the pipeline through the teat cups to a value less than the upper third predefined energy parameter value,
• the commencement of milk flowing in the pipeline in response to the computed energy parameter value transitioning from one of a value indicative of the teat cups of the milking cluster being attached to the teats of the animal without milk flowing in the pipeline, and a value indicative of air being drawn under vacuum into the pipeline through the teat cups to a value indicative of milk flowing in the pipeline, and
• the ceasing of milk to flow in the pipeline in response to the computed energy parameter value transitioning from a value indicative of milk flowing in the pipeline to a value less than the second predefined energy parameter value.