Abstract: The vortex flow pickup (1) serves for measuring the mass flow, the volume flow or the flow velocity of a fluid which is flowing in a measuring tube (2) having a tube wall (21), and has a temperature sensor (34) arranged in such a way that the vortex flow pickup may also be used together with those fluids which corrode the temperature sensor. A bluff body (4) which produces vortices, and consequently pressure fluctuations, is arranged in the measuring tube. A vortex sensor (3) responding to these pressure fluctuations is fitted downstream of the bluff body in a bore (22) of the tube wall (21) of the measuring tube. The vortex sensor (3) comprises a diaphragm (33) which covers the bore (22) and on which a sensor vane (31) protruding into the fluid is fastened. The temperature sensor (34) is fixed on the bottom of a blind hole (314) of the sensor vane. On the side of the diaphragm lying opposite the sensor vane, a sensor element (35) is fastened.

Abstract: A transit time ultrasonic flow sensor uses a pair of transducers that alternate between transmitting and receiving operational states, the operating frequency of a reference oscillator driving the transmitting transducer is controllably varied so as to maintain a constant phase relationship between the transmitted and received signals. A second oscillator is slaved, in frequency to the reference oscillator just before the alternation in operational states takes place and retains that frequency for most of the next operational state, and so forth. Fluid flowing along a line between the two transducers causes one of the two oscillators to swing to a higher frequency, and the other to swing low with respect to each other. A difference frequency between the two oscillators is detected and used as a basis for calculating the rate of fluid flow. In preferred versions of the invention the pair of transducers and an acoustic reflector are configured as a probe that can be inserted into the flowing fluid.

Abstract: A method for measuring fluid flow includes generating vortices in a fluid and relating the fluid flow to a first set of fluid parameters to obtain a first relationship, and relating the fluid flow to a second set of fluid parameters to obtain a second relationship. The first and second sets of fluid parameters are monitored. A first flow value is calculated from the first set of monitor fluid parameters and the first relationship. The second relationship is adjusted based on the first flow value. The output value is calculated from the second set of monitored fluid parameters and the adjusted second relationship.

Abstract: The invention encompasses a vortex flowmeter for measuring the flow rate of a fluid by detecting an alternating signal produced by Karman vortices using a sensor comprising a low pass filter for passing the frequency band of the alternating signal that is determined by the diameter and flow rate range of the vortex flowmeter; subband filters for splitting the frequency band passing through the low pass filter into a plurality of component bands; a spectrum analyzer for analyzing the plurality of component bands; and a bandpass filter for passing a frequency band to be measured according to the analysis results of the spectrum analyzer, thereby providing flow rate measurement with high precision.

Abstract: A process variable transmitter, implemented in a dual PLL structure, includes a first PLL having a first bandwidth producing a first output signal, and a second PLL having a second bandwidth narrower than the first bandwidth of the first PLL. The first and second PLLs are operable to lock into a frequency of an input signal and produce first and second output signals, respectively. The second PLL is operable to lock into the frequency of the input signal with greater accuracy and greater immunity to noise than the first PLL. A switch is operable to switch an output signal of the process variable transmitter between the first output signal and the second output signal.

Abstract: A vortex flow meter includes a measuring tube in which a fluid is carried, a vortex generator provided in the measuring tube for developing a Karman vortex in the fluid, a magnetic field generator generating a magnetic field across the measuring tube downstream of the vortex generator, a pair of electromotive force measuring electrodes provided downstream of the vortex generator for measuring an electromotive force generated by the Karman vortex passing across the magnetic field, a pair of reference electrodes provided at locations upstream and downstream of the electromotive force measuring electrodes, respectively, for measuring a potential at each location, and a detector circuit electrically connected to the electromotive force measuring electrodes and the reference electrodes for calculating the flow of the fluid from the electromotive force and the potential measured by the reference electrodes.

Abstract: A vortex sensor senses the vortices generated by a vortex generator. A temperature sensor, disposed at a streamlined body within a flow tube, measures a temperature of fluid carried by the flow tube. A circuit coupled to the vortex sensor and to the temperature sensor creates an output indicative of the flow.

Abstract: A method for determining the pulsatile flow characteristics in fluid flow driven by a periodic pressure disturbance includes the step of evaluating the spectrum of a signal representative of the vortices generated by a vortex flowmeter. Because of the periodic pressure disturbance, the signal is an FM signal in which a carrier, having a frequency corresponding to the vortex-shedding frequency in the absence of pulsating flow, is modulated by the periodic pressure disturbance. The pulsation frequency and amplitude are then estimated on the basis of the separation between adjacent sidebands of the spectrum of the FM signal and the relative amplitudes of the sidebands.

Abstract: This sensor for measuring the flow velocity and/or the flow rate of a fluid provides an optical sensor system which is also suitable for use at temperatures higher than 400° C., does not come into contact with the fluid, and requires less space than conventional optical sensor systems. The sensor comprises a tube (1) through which the fluid flows in a first direction and which has a wall (11) in which a first window (2) and a second window (3) of optical, schlieren-free, high-temperature glass are set fluid-tight and pressure-tight at points lying opposite each other along a first tube diameter. A bluff body (4) is disposed along a second tube diameter and fixed in the tube for generating Kármán vortices, whose frequency f is proportional to the flow velocity u. The second diameter is up-stream of, and perpendicular to, the first.

Abstract: The piezoelectric vortex sensing element (3, 3′, 3″, 3+) of this vortex flow sensor (1) can be assembled from individual components in a simple manner; if its piezoelectric element (34, 34′, 34″, 34*, 34+, 34++) should be faulty, it can be easily replaced. Also, the vortex sensing element can be made largely insensitive to vibrations acting from outside. The vortex flow sensor (1) serves to measure the flow velocity and/or the volumetric flow rate of a fluid flowing through a measuring tube (2). A bluff body (4) generating Kármán vortices is disposed along a diameter of the measuring tube and fixed to the measuring tube at at least one fixing point (41). The vortex sensing element responds to vortex-induced pressure fluctuations and either is installed in a wall (22) of the measuring tube down-stream of the bluff body in a tight manner or extends into a main bore (46) extending through the measuring tube into the bluff body.

Abstract: A vortex flow meter includes a measuring tube in which a fluid is carried, a vortex generator provided in the measuring tube for developing a Karman vortex in the fluid, a magnetic field generator generating a magnetic field across the measuring tube at the downstream of the vortex generator, a pair of electromotive force measuring electrodes provided at the downstream of the vortex generator for measuring an electromotive force generated by the Karman vortex passing across the magnetic field, a pair of reference electrodes provided at the upstream and downstream of the electromotive force measuring electrodes, respectively, for measuring a potential at each location, and a detector circuit electrically connected to the electromotive force measuring electrodes and the reference electrodes for calculating the flow of the fluid from the electromotive force and the potential measured by the reference electrodes.

Abstract: To achieve accuracies of the order of 0.75% of the measured value, a digitized, two-dimensional overall image of a bluff body (7), of the internal surface of a measuring tube (2) in the area of the bluff body, of the two fixing zones (71, 72) of the bluff body, and of contour line (51) of the inlet end (5) of the measuring tube is generated by a high-resolution electronic camera (9) located in front of the measuring tube (2) on the axis (3) of this tube. The overall image is divided into three partial images. The first partial image contains only information about the inlet end (5) and the internal surface (4) of the measuring tube, the second contains only information about the bluff body (7) without the fixing zones (71, 72), and the third contains only information about the fixing zones. From shape information about the fixing zones (71, 72) and ideal information characteristic of the ideal shapes of the fixing zones, cross-correlation information is formed.

Abstract: A vortex shedding flowmeter includes a sensor assembly received within a sleeve assembly that has a sensor tab extending into the fluid stream. The sleeve assembly includes a flexible sleeve portion that can flex slightly in the presence of vortices. The flexible sleeve exerts a force on a rocker arm of the sensor assembly which causes the sensor assembly to pivot about a pair of piezoelectric crystals mounted therein. A unique electrode pad and split electrode arrangement relative to the piezoelectric crystals is employed to provide the voltage signals from the piezoelectric crystals to a sensing circuit. The flowmeter can be used in either in-line or insertion applications.

Abstract: A vortex flowmeter capable of measuring the flow rate of fluid flowing through a pipe bidirectionally or in a pulsating manner while measurement error is substantially nulled. The vortex flowmeter includes a first vortex-generating body 2a disposed within a pipe 1 for generating a Karman vortex m for a flow in one direction, a second vortex-generating body 2b disposed within the pipe 1 for generating a Karman vortex m for a flow in the opposite direction, and vortex detection means X and Y for detecting a Karman vortex generated by each of the vortex-generating bodies 2a and 2b. When applied to the case where backward flow is generated in fluid flowing through a pipe in a regular direction to thereby cause a pulsating flow, the vortex detection means X and Y detect the Karman vortexes, and subtraction is performed on output values represented, for example, by the number of pulses to thereby take into account the influence of backward flow on the regular flow, thereby determining an accurate flow rate.

Abstract: A vortex detector for low flow rates comprises a vane that is located downstream from a vortex generator and is connected at only one end in a canthever manner to a cylindrical housing, which defines a flow passage. The end of the vane connected to the housing includes an area of reduced thickness that acts as a resilient, plastic hinged joint to make it easier for weak vortices generated by the vortex generator to impart vibrations or deflections to of the vane. Strain gauge transducers in the area of reduced thickness detect deflections or vibrations of the vane and produce analog electric signals having amplitudes and frequencies that are related to the strengths, frequencies, and period of the vortices.

Abstract: The invention relates to a vortex flow meter for ultra pure applications. The vortex flow meter of the invention employs a smooth and continuous fluorocarbon layer to coat a number of fluid accessible surfaces of the flowmeter. The coating prevents or minimizes contact between the process fluid and the fluid accessible surfaces of the flowmeter, thus allowing the flow meter to measure the flow rate of a process fluid having a level of purity of typically one part per trillion without contaminating the fluid. The flowmeter of the invention is advantageously less costly and more accurate than conventional flow meters for ultra pure applications.

Abstract: A Kármán vortex flowmeter includes a vortex generator 2 provided in a tube-like flow passage 1a, a vortex detector 4 having a piezoelectric element 6 embedded in an elastic sheath 5 having a pressure receiving wing piece 5a, spaced apart by a prescribed distance from the vortex generator, downstream of the flow passage. The vortex detector includes the pressure receiving wing piece of a square plate, and a piezoelectric element accommodating portion 5c of a circular cylinder having a larger outer diameter than the pressure receiving wing piece. The pressure receiving wing piece protrudes from an end face 5c of the piezoelectric element accommodating portion. In this configuration, a Kármán vortex flowmeter with high accuracy can be provided in which the detector itself generate no vortex and can detect vortexes stably.

Abstract: A vortex detector comprises a generally cylindrical housing or body that defines a flow passage extending from an upstream end to a downstream end. A vortex generator disposed diametrically across the cylindrical housing near the upstream end of the cylindrical housing and oriented substantially perpendicular to the longitudinal central axis of the flow passage generates a vortex street in a fluid flowing in the flow passage. The vortex street created by the vortex generator impacts a vane located downstream of the vortex generator and connected at one end to the cylindrical housing substantially spans the flow passage diametrically and substantially parallel to the vortex generator such that vibrations or motion are generated in the vane. The end of the vane connected to the housing includes an area of reduced thickness that acts as a resilient, elastic hinged joint for the motion of the vane.

Abstract: A transit time ultrasonic fluid flow sensor is configured as a self contained modular unit that does not rely on acoustic transmissions through or reflected by a pipe for operation. A highly efficient transducer assembly transmits and receives signals which are well isolated from each other and which enables simplification of the supporting electronics. Continuous wave transmission and reception of the acoustic signals, and provision for acoustic path and electronic drifts enable the sensors to be physically small and yet to exhibit high sensitivity and measurement precision. Some versions of the apparatus sense flow along two orthogonal axes. In addition, electrolytic cleaning is provided for some versions of the sensor.

Abstract: A vortex sensor senses the generated vortices and provides a vortex signal. A filtering circuit is coupling to the vortex sensor to receive the vortex signal and provide an output indicative of fluid flow. A temperature sensor senses a temperature of the fluid and provides a temperature value, while a pressure sensor senses a pressure of the fluid and provides a pressure value. A processor is operably coupled to the filtering circuit, the temperature sensor, and the pressure sensor for receiving the output, the temperature value, and the pressure value, respectively. The processor calculates a calibration factor as a function of the output, the temperature value, and the pressure value for use in calculating the output value indicative of the flow rate of the fluid.