Abstract: The disclosure relates to a method for operation of a flow measurement device, and to a flow measurement device itself. In order in this case to record the conductivity of the medium or faults resulting from deposits by means of a measurement tube configuration in a technically simple manner, a total of at least 4 electrodes are arranged distributed on the circumference of the measurement tube, in the measurement tube. When a signal is fed in at one of the electrodes or at an electrode pair, an electric current is measured between one electrode pair, while an electrical voltage is measured between another electrode pair. An impedance value is determined from the two measured values, from which impedance value a conductivity of the medium is determined and/or in comparison of different conductivities or in comparison with historical values, it is deduced that there is a covering layer on the electrodes.

Abstract: An electromagnetic flowmeter assembly is described in which an excitation field is set up across a flow conduit and electrodes are used to sense the electromagnetic field generated across the flow conduit as a result of interaction between the excitation field and fluid flowing along the flow conduit. The signals obtained from the electrodes are processed, together with stored calibration data, by processing circuitry to determine flow measurements and means is provided for dynamically updating the calibration data.

Abstract: The disclosure relates to a method for operation of a flow measurement device, and to a flow measurement device itself. In order in this case to record the conductivity of the medium or faults resulting from deposits by means of a measurement tube configuration in a technically simple manner, a total of at least 4 electrodes are arranged distributed on the circumference of the measurement tube, in the measurement tube. When a signal is fed in at one of the electrodes or at an electrode pair, an electric current is measured between one electrode pair, while an electrical voltage is measured between another electrode pair. An impedance value is determined from the two measured values, from which impedance value a conductivity of the medium is determined and/or in comparison of different conductivities or in comparison with historical values, it is deduced that there is a covering layer on the electrodes.

Abstract: An electromagnetic flowmeter assembly is described in which an excitation field is set up across a flow conduit and electrodes are used to sense the electromagnetic field generated across the flow conduit as a result of interaction between the excitation field and fluid flowing along the flow conduit. The signals obtained from the electrodes are processed, together with stored calibration data, by processing circuitry to determine flow measurements and means is provided for dynamically updating the calibration data.

Abstract: Methods and apparatus for determining the phase of a signal in a measurement device having a digital signal processor are described. The signal is digitised and the digitised signal, or a signal derived therefrom, is numerically correlated with a numerically generated reference signal. In one embodiment, the reference signal has a predetermined phase. In a further embodiment, the numerically generated reference signal has a reference phase and the phase is determined from the result of the correlation. The techniques described herein may reduce the amount of information lost in determining the signal phase.

Abstract: A method of obtaining a measure of flow from an electromagnetic flow meter is disclosed. A shaped excitation waveform is applied to the flow meter and an output is received from the meter. The sampled output data from the meter is then resolved into a non-flow waveform component and a flow waveform component to derive a measure of flow. Resolving the data into expected waveform components rather than correlating each frequency component of the sampled output data with a sine wave may allow readings to be obtained without processing each frequency component separately. Also, the method may allow more accurate removal of the non-flow component from the output signal, and may decrease the time delay before the initial reading and allow the use of a greater reading repetition rate.

Abstract: There is described herein a method of obtaining a measure of flow from an electromagnetic flow meter having at least one field generating coil and potential sensing electrodes. A composite excitation waveform is applied to the field-generating coil. The composite excitation waveform comprises at least two frequency components and a plurality of frequency components are simultaneously present for at least a portion of the waveform. The potential sensed by the potential sensing electrodes is sampled to produce a sampled output and the sampled output is correlated with a composite waveform based on the composite excitation waveform. The result of the correlating is used to derive a measure of flow.

Abstract: Methods and apparatus for determining the phase of a signal in a measurement device having a digital signal processor are described. The signal is digitised and the digitised signal, or a signal derived therefrom, is numerically correlated with a numerically generated reference signal. In one embodiment, the reference signal has a predetermined phase. In a further embodiment, the numerically generated reference signal has a reference phase and the phase is determined from the result of the correlation. The techniques described herein may reduce the amount of information lost in determining the signal phase.

Abstract: A method of obtaining a measure of flow from an electromagnetic flow meter is disclosed. A shaped excitation waveform is applied to the flow meter and an output is received from the meter. The sampled output data from the meter is then resolved into a non-flow waveform component and a flow waveform component to derive a measure of flow. Resolving the data into expected waveform components rather than correlating each frequency component of the sampled output data with a sine wave may allow readings to be obtained without processing each frequency component separately. Also, the method may allow more accurate removal of the non-flow component from the output signal, and may decrease the time delay before the initial reading and allow the use of a greater reading repetition rate.

Abstract: There is described herein a method of obtaining a measure of flow from an electromagnetic flow meter having at least one field generating coil and potential sensing electrodes. A composite excitation waveform is applied to the field-generating coil. The composite excitation waveform comprises at least two frequency components and a plurality of frequency components are simultaneously present for at least a portion of the waveform. The potential sensed by the potential sensing electrodes is sampled to produce a sampled output and the sampled output is correlated with a composite waveform based on the composite excitation waveform. The result of the correlating is used to derive a measure of flow.

Abstract: In a vibrating tube meter such as a Coriolis meter, an accurate measurement of a fluid parameter such as density can be obtained, substantially independent of stress, by measuring vibrational characteristics, particular resonant frequencies of two different vibrational modes. Stress or other variables can be determined from the measurement. Because the measurement of or compensation for stress is based directly on the vibrational characteristics, better accuracy may be obtained than by using a conventional strain gauge to measure stress. The techniques disclosed can give accurate results without requiring particular constraints on meter design.

Abstract: In a coriolis flow meter, two drivers are provided and a measure of mass flow rate derived from the adjustment of the input signals to each driver required to achieve a desired phase shift in the output. This may give higher accuracy compared to conventional meters in which the phase shift is simply measured, and may also enable determination of other characteristics of the fluid.