Abstract: A controller for a flowmeter includes an input module operable to receive a sensor signal from a sensor connected to a vibratable flowtube. The sensor signal is related to a fluid flow through the flowtube. The controller also includes a signal processing system operable to receive the sensor signal, determine sensor signal characteristics, and output drive signal characteristics for a drive signal applied to the flowtube. An output module is operable to output the drive signal to the flowtube and a control system is operable to modify the drive signal and thereby maintain oscillation of the flowtube during a transition of the flowtube from a substantially empty state to a substantially full state.

Abstract: A controller for a flowmeter includes an input module operable to receive a sensor signal from a sensor connected to a vibratable flowtube. The sensor signal is related to a fluid flow through the flowtube. The controller also includes a signal processing system operable to receive the sensor signal, determine sensor signal characteristics, and output drive signal characteristics for a drive signal applied to the flowtube. An output module is operable to output the drive signal to the flowtube and a control system is operable to modify the drive signal and thereby maintain oscillation of the flowtube during a transition of the flowtube from a substantially empty state to a substantially full state.

Abstract: Techniques for measuring a density of a liquid within a fluid that includes both a liquid and a gas are described. A pressure of the fluid oscillates according to a time-varying function, which causes a density of the fluid also to oscillate according to the same time-varying function. A resulting pressure signal and density signal are analyzed to extract at least a first and second pressure value and at least a first and second density value, where the first pressure and density values occur at a first time, and the second pressure and density values occur at a second time. Then, the liquid density is calculated from the first and second pressure and density values. As a result, the liquid density may be calculated quickly and easily, with a minimum of effort on the part of an operator, and without requiring disruption of other measurement processes associated with the flowtube.

Abstract: Two-wire transmitters are described in which the required voltage that a control room must supply to the transmitter is lower at high current than at low current, thus freeing up more voltage for other uses, and in which a constant set of operating voltages may be maintained. A corrected pressure in a vortex flow meter may be determined that reflects the mass flow rate. Thus, the mass flow rate may be determined based on the corrected pressure reading and a measured volumetric flow rate. Density may be determined from pressure and temperature using a table containing error values based on a standard density determination and a relatively simple approximation. During operation of a flow meter, the stored error values may be linearly interpolated and the approximation may be computed to determine the density from the stored error value.

Abstract: A controller for a flowmeter includes an input module operable to receive a sensor signal from a sensor connected to a vibratable flowtube. The sensor signal is related to a fluid flow through the flowtube. The controller also includes a signal processing system operable to receive the sensor signal, determine sensor signal characteristics, and output drive signal characteristics for a drive signal applied to the flowtube. An output module is operable to output the drive signal to the flowtube and a control system is operable to modify the drive signal and thereby maintain oscillation of the flowtube during a transition of the flowtube from a substantially empty state to a substantially full state.

Abstract: Techniques for measuring a density of a liquid within a fluid that includes both a liquid and a gas are described. A pressure of the fluid oscillates according to a time-varying function, which causes a density of the fluid also to oscillate according to the same time-varying function. A resulting pressure signal and density signal are analyzed to extract at least a first and second pressure value and at least a first and second density value, where the first pressure and density values occur at a first time, and the second pressure and density values occur at a second time. Then, the liquid density is calculated from the first and second pressure and density values. As a result, the liquid density may be calculated quickly and easily, with a minimum of effort on the part of an operator, and without requiring disruption of other measurement processes associated with the flowtube.

Abstract: A flowmeter includes a vibratable conduit, a driver connected to the conduit and operable to impart motion to the conduit, and a sensor connected to the conduit and operable to sense the motion of the conduit. A control and measurement system is connected to the driver and the sensor. The control and measurement system includes circuitry to receive a sensor signal from the sensor, generate a drive signal based on the sensor signal, supply the drive signal to the driver, and generate a measurement of a property of material flowing through the conduit based on the sensor signal.

Abstract: A digital flowmeter includes a vibratable conduit, a driver connected to the conduit and operable to impart motion to the conduit, and a sensor connected to the conduit and operable to sense the motion of the conduit. A control and measurement system is connected to the driver and the sensor. The control and measurement system includes circuitry to receive a sensor signal from the sensor, generate a drive signal based on the sensor signal using digital signal processing, supply the drive signal to the driver, and generate a measurement of a property of a two-phase material flowing through the conduit based on the signal from the sensor.

Abstract: Two-wire transmitters are described in which the required voltage that a control room must supply to the transmitter is lower at high current than at low current, thus freeing up more voltage for other uses, and in which a constant set of operating voltages may be maintained. A corrected pressure in a vortex flow meter may be determined that reflects the mass flow rate. Thus, the mass flow rate may be determined based on the corrected pressure reading and a measured volumetric flow rate. Density may be determined from pressure and temperature using a table containing error values based on a standard density determination and a relatively simple approximation. During operation of a flow meter, the stored error values may be linearly interpolated and the approximation may be computed to determine the density from the stored error value.

Abstract: A flowmeter includes a vibratable conduit, a driver connected to the conduit and operable to impart motion to the conduit, and a sensor connected to the conduit and operable to sense the motion of the conduit. A control and measurement system is connected to the driver and the sensor. The control and measurement system includes circuitry to receive a sensor signal from the sensor, generate a drive signal based on the sensor signal, supply the drive signal to the driver, and generate a measurement of a property of material flowing through the conduit based on the sensor signal.

Abstract: A digital flowmeter includes a vibratable conduit, a driver connected to the conduit and operable to impart motion to the conduit, and a sensor connected to the conduit and operable to sense the motion of the conduit. A control and measurement system is connected to the driver and the sensor. The control and measurement system includes circuitry to receive a sensor signal from the sensor, generate a drive signal based on the sensor signal using digital signal processing, supply the drive signal to the driver, and generate a measurement of a property of a two-phase material flowing through the conduit based on the signal from the sensor.

Abstract: A digital flowmeter includes a vibratable conduit, a driver connected to the conduit and operable to impart motion to the conduit, and a sensor connected to the conduit and operable to sense the motion of the conduit. A control and measurement system is connected to the driver and the sensor. The control and measurement system includes circuitry to receive a sensor signal from the sensor, generate a drive signal based on the sensor signal using digital signal processing, supply the drive signal to the driver, and generate a measurement of a property of a two-phase material flowing through the conduit based on the signal from the sensor.

Abstract: A digital flowmeter includes a vibratable conduit, a driver connected to the conduit and operable to impart motion to the conduit, and a sensor connected to the conduit and operable to sense the motion of the conduit. A control and measurement system is connected to the driver and the sensor. The control and measurement system includes circuitry to receive a sensor signal from the sensor, generate a drive signal based on the sensor signal using digital signal processing, supply the drive signal to the driver, and generate a measurement of a property of a two-phase material flowing through the conduit based on the signal from the sensor.

Abstract: A digital flowmeter includes a vibratable conduit, a driver connected to the conduit and operable to impart motion to the conduit, and a sensor connected to the conduit and operable to sense the motion of the conduit. A control and measurement system is connected between the driver and the sensor. The control and measurement system includes circuitry to receive a sensor signal from the sensor, generate a drive signal based on the sensor signal using digital signal processing, supply the drive signal to the driver, and generate a measurement of a property of material flowing through the conduit based on the signal from the sensor.

Abstract: Drivers and sensors in Coriolis-type mass flowmeters are used to monitor and predict flowmeter failure modes due to mechanical deterioration during meter operation. The relative values of two different signals, e.g, resonant frequencies, associated with Coriolis flow conduit motion are monitored as an indicator of excessive mechanical deterioration and also used to compensate for shifts in meter factor. The noise spectrum of the sensor output is also monitored to indicate mechanical fatigue of the tubes. Energy loss in the vibrating tubes is monitored as an indication of fatigue to determine tube failure by determining the drive power needed to maintain constant velocity oscillation or measuring the decay rate of the drive signal when driver power is interrupted.

Abstract: A method and apparatus for increasing the resolution and accuracy of flow measurements made by vortex flowmeters through the use of an adaptive filter. A vortex sensor signal is conditioned by a bandpass filter whose corner frequencies are dynamically altered as a function of the measured frequency of the vortex sensor signal. When the change in frequency is relatively small, the filters' corner frequencies are set to track the frequency signal in accordance with a specified bandwidth thereby improving the signal-to-noise ratio. For large frequency changes, a new frequency signal is searched for thereby avoiding tracking erroneous noise signals. Furthermore, compensation for additional or missed vortex pulses is made thereby generating a more accurate vortex frequency measurement.

Abstract: A vortex sensor 14 measures a flow rate of a fluid flowing through a flow passage by detecting alternating pressure variations 26a and 28a generated by a shedding body 16 placed in the flow passage. The vortex sensor 14 includes a sensor housing 32 enclosing piezoelectric sensing elements 62, 64 which are acted on by a movable member 30. The lifetime of the sensing elements in the closed interior is enhanced by providing surface barriers, oxidizing exposed interior surfaces, or providing a gas reservoir. In applications where fluid leakage may be accepted, a controlled leak restrictor provides a limited rate diffusion path to the atmosphere allowing a minimum partial pressure of oxygen to be maintained.

Abstract: A vortex sensor 14 for measuring a flow rate of a fluid flowing through a flow passage. The flow rate is measured by detecting alternating pressure variations 26a and 28a generated by a shredding body 16 placed in the flow passage. The vortex sensor 14 includes a sensor housing 32 having two cavities 44 and 46 interconnected by a channel 42. An Axle 52 of a spool member 34 is slideably disposed in the channel 42 and allows each of two flange members 54 and 56, connected proximate each end of the axle 52, to shuttle back and forth with respect to the sensor housing 32. A piezoelectric sensing element 62, 64 and a biasing mechanism 58, 60 are disposed between the flange members 54 and 56 and the sensor housing 32. The alternating pressure variations are applied to each flange member 54, 56 causing the spool member 34 to shuttle back and forth. When the spool 34 moves, mechanical forces are coupled to each sensing element 62 and 64 by biasing mechanisms 58 and 60.

Abstract: An ultrasonic flowmeter of the upstream/downstream sonic propagation type includes two transducers mounted externally on the same side of a flow conduit. The transducers are coupled to respective sonic probes which transmit and receive acoustic pulses between the transducers through the fluid by "bouncing" the pulses off the opposite pipe wall. Additionally the meter maintains a smooth bore in the measurement region so that the acoustic pulses are refracted at the probe/fluid interface and hence propagate along a sonic path that varies depending on the sonic velocities within the fluid and the probe. An acoustic path of known length is included within at least one of the probes along which a portion of the generated acoustic pulses propagates, thereby providing for a third sonic measurement which represents the transmit time in the probe.