The method of periodic auto-calibration a device for measuring the flow of alternating pressure drop directly in terms of their operation, which are widely used in various industrial sectors for the control and accounting costs of various liquid substances (oil, hot water, food, etc.). The basis of the method is based on the use of structural and temporal redundancy measurement conversions, enabling algorithmic way to identify and consider an amendment to the progressive flow errors as additive and multiplicative nature. As aresult of increased flow metrological reliability in the process of continuous operation and, therefore, the reliability of process control volumetric flow of liquid substances