Abstract: An ultrasonic flow sensor having at least one ultrasonic converter (A, B) for transmitting and receiving ultrasonic signals (A0, B0) and a receiver unit (4) that is connected to the ultrasonic converter (A, B) and determines a zero crossing (N) of the ultrasonic signal (A0, B0) as a reception time (t0) once the ultrasonic signal (A0, B0) has exceeded a predetermined threshold value (SW). The measurement precision can be significantly improved if the receiver unit (4) determines a piece of information about an amplitude (Amp) of the ultrasonic signal (A0, B0) and varies the threshold value (SW) based on the information determined.

Abstract: A transcutaneous energy transfer system with subcutaneous non coupled coils is used to transmit power and signals to an implanted biological support device or sensor, such as a flow sensor for measuring relatively low flow rates, such as hydrocephalic shunt flow. The flow sensor is configured to convert a shear wave generated by a transducer to a longitudinal wave at the interface of a signal pathway and the flow, wherein the longitudinal wave travels parallel to the flow and exits a flow channel to convert to a shear wave which intersects a second transducer. The transcutaneous energy transfer employs a pair of inductive coupling coils, wherein the coils are disposed in zero coupling orientation which can include a perpendicular orientation of corresponding coil axes.

Abstract: A photo-acoustic flow meter for use in dialysis is described, that uses an optical beam to generate an acoustic signal in the fluid for which the flow rate is to be measured. The phase angle of the acoustic signal changes when traversing upstream and when traversing downstream. The phase difference between the acoustic signals received upstream and downstream, compared with a reference source signal is measured, and it yields the flow rate of the fluid.

Abstract: An ultrasonic flow measuring device for determining and/or monitoring volume- and/or mass-flow of a measured medium through a pipeline or measuring tube. The wall of the pipeline or measuring tube is provided, in the region of the defined sensor position of the ultrasonic sensor and/or in the region of the sound path of the ultrasonic measuring signals of the at least one ultrasonic sensor, with a deformation or deformations, which is/are embodied and/or arranged in such a manner that the flow velocity of the medium measured in the sound path, or, in the case of plural ultrasonic sensors, the measured and/or the combined flow velocities of the medium in the sound paths correspond/corresponds at least approximately to average flow velocity of the medium averaged over the area of the pipeline or measuring tube.

Abstract: An ultrasonic flow rate measuring device for measuring the flow rate of a medium flowing through a line (1), with at least one ultrasonic transducer (2) and a guide frame (3) for guiding and holding the ultrasonic transducer (2). An electrical connecting box (12) which has a connection (13) for a cable (14) to the ultrasonic transducer (2) and a connection (15) for a cable (16) to the measuring device electronics is provided. Thus, in a clamp-on ultrasonic flow rate measuring device, simple cabling is achieved.

Abstract: Method and device that by acoustic signal energy- generated by a flowing medium, detects characteristic properties, amounts and the individual distribution between several components/phases, i.e. liquids, gases, particles or any distribution individual and between these. The flowing medium is decided to pass through at least one in a pipe system installed flow conditioner that has at least one restriction and by said passing is decided to release acoustic signal energy. The flow conditioner is installed in such a way that it in an acoustic and/or thermal way is totally or partly isolated from upstream and downstream adjoining sections of the pipe system and/or surrounding construction details.

Abstract: In an ultrasonic flowmeter of the time difference type using annular ultrasonic transducers, to obtain an accurate flow volume without correction by actual flow, from theoretical formulas which are taking properties of the fluid such as density, and dimension, and properties of the measuring tube into consideration.

Abstract: A device for determining and/or monitoring volume and/or mass flow rate of a medium that flows in a direction of flow through a pipeline/measuring tube of inner diameter. The device comprises at least two ultrasonic transducers that emit and/or receive ultrasonic measuring signals along defined sonic paths and a control/evaluation device which determines the volume flow rate and/or the mass flow rate of the medium to be measured inside said pipeline/measuring tube based on the ultrasonic measuring signals according to the travel-time difference principle. In order to provide a multichannel ultrasonic flowmeter, at least one reflector element is placed in the interior of the pipeline/measuring tube. The reflector element has a defined distance from the inner surface of the pipeline/measuring tube and is placed within the sonic path of the ultrasound measuring signals running through the pipeline/measuring tube.

Abstract: The present invention relates to a plastic ultrasonic measurement section (1) used for the flow measurement of fluids. It is equipped with two ultrasonic transmitting and receiving transducers (2, 3) spaced in the fluid flow direction and is characterized in that the sound is guidable in Z-shaped manner between the transmitting and receiving transducers (2, 3) by means of at least two reflectors (4). A description is given of a corresponding measurement method and a method for the one-piece production of a measurement section (1) by injection moulding.

Abstract: A probe system for measuring fluid flow in a conduit, such as a blood vessel with ultrasound transit time or similar measurement methods. The probe system having a probe body with a space to receive in a secure but detachable fashion a pliable soft insert. The insert has a central lumen or aperture which is sized to securely but detachably fit around a vessel or conduit without squeezing or in any way altering the conduit during application or use. The insert is acoustically matched with the vessel or conduit and fluid flowing therein to thereby minimize distortion or attenuation of ultra sound waves generated to assess flow. In a further aspect a set of inserts with varying sized lumens or apertures are provided to match with vessels or conduits of varying size. The system among other things increases accuracy of flow measurements while minimizing trauma to the vessel or conduit.

Abstract: An ultrasonic flow sensor having at least one ultrasonic converter (A, B) for transmitting and receiving ultrasonic signals (A0, B0) and a receiver unit (4) that is connected to the ultrasonic converter (A, B) and determines a zero crossing (N) of the ultrasonic signal (A0, B0) as a reception time (t0) once the ultrasonic signal (A0, B0) has exceeded a predetermined threshold value (SW). The measurement precision can be significantly improved if the receiver unit (4) determines a piece of information about an amplitude (Amp) of the ultrasonic signal (A0, B0) and varies the threshold value (SW) based on the information determined.

Abstract: A device for determining and/or monitoring the volume, and/or mass, flow of a medium flowing through a containment in a stream direction. The device includes: At least one ultrasonic transducer, which emits and/or receives ultrasonic measuring signals; and a control/evaluation unit, which determines the volume, and/or mass, flow of the medium in the containment on the basis of the ultrasonic measuring signals according to the travel time difference principle or the Doppler principle. A first clock-pulse generator having a first pulse rate and a second clock-pulse generator having a second pulse rate are provided, with the first pulse rate of the first clock-pulse generator being greater than the second pulse rate of the second clock-pulse generator. The control/evaluation unit operates the first clock-pulse generator intermittently. The control/evaluation unit sizes the duration of a switch-on, or measuring, phase and/or a resting phase as a function of the available energy.

Abstract: A system is shown for injecting a chemical, such as an odorant, from a chemical supply into a fluid containing system such as a natural gas pipeline or an LPG pipeline. A tank of odorant is maintained under a positive pressure which exceeds that of the pipeline. An injection conduit communicates the odorant tank with the pipeline. A precise control flow valve, located within the injection conduit, meters odorant to be injected into the pipeline. An ultrasonic measuring unit allows the odorant to be metered on a drop wise basis with drops of chemical being counted as they pass through the flow valve into the injection conduit and into the natural gas pipeline. The ultrasonic measuring unit also allows steady state flow conditions to be measured accurately. A sonic measuring unit can also be utilized in low flow situations.

Abstract: Measuring volume flows or mass flows in the intake system of motor vehicle internal combustion engines plays an important role in reducing harmful emissions. Therefore, an ultrasonic flow meter for measuring a flow velocity of a fluid flowing in an essentially laminar flow in the main flow direction is described. The ultrasonic flow meter has at least two ultrasonic transducers, the ultrasonic transducers being able to emit and/or receive ultrasonic waves at an angle ? to the main flow direction which is different from 90°. Furthermore, the ultrasonic flow meter has at least one turbulator situated upstream from at least one ultrasonic transducer in the main flow direction of the fluid, which generates longitudinal eddies in at least one zone adjacent to the at least one ultrasonic transducer, in particular in a protrusion in a wall of a flow pipe and thus improves the flow of the fluid in this zone in the flow pipe.

Abstract: A flowmeter for measuring a flow velocity of a fluid in a pipeline includes a measuring tube having opposite ends. Two ultrasonic transducers are disposed respectively at the opposing ends of the measuring tube, and two connection pipes are provided for attachment of the flowmeter to the pipeline and extend in axial relationship to the pipeline.

Abstract: An apparatus and method for measuring a flow velocity profile of fluid traveling in a pipe or conduit uses an ultrasonic wave transmitted from an ultrasonic wave transducer mounted at an angle on the outside of a pipe using a wedge, and made incident onto the fluid in the pipe to measure the fluid flow velocity profile, using the principle that a frequency of an ultrasonic wave, reflected by a reflector existing in the fluid, is changed depending on a flow velocity due to Doppler effect. The transmission frequency and the angle of incidence onto the pipe can be selected to suppress frequency dependence of a measured value due to Lamb wave and allow the flow velocity or flow rate of fluid to be measured with a greater accuracy.

Abstract: In order to be able to couple as great a fraction as possible of ultrasonic measuring signals into a medium to be measured, an ultrasonic sensor is provided with a cup-shape and includes a housing and an oscillatable unit for producing the ultrasonic signals. The oscillatable unit is composed of a plurality of components and is so embodied that it has a node plane, which is oriented essentially perpendicularly to the radiating or receiving direction of the ultrasonic measuring signals. At least a portion of the outer surface of the oscillatable unit is connected with the housing in the region of the node plane of the oscillatable unit.

Abstract: A method and system for driver configuration for an ultrasonic meter. At least some of the illustrative embodiments are ultrasonic meters comprising a spool piece that couples within a flow of fluids, a first upstream transducer mechanically coupled to the spool piece, a first downstream transducer mechanically coupled to the spool piece (the first downstream transducer in operational relationship to the first upstream transducer), and a first transducer driver that selectively couples to the first upstream and first downstream transducers. The transducer driver drives the first upstream transducer, and also drives the first downstream transducer.

Abstract: In an ultrasonic flow meter for measuring a flow rate of a fluid flowing through a conduit by detecting a propagating time difference between a forward propagating time of an ultrasonic wave propagating within the conduit in a forward direction and a backward propagating time of an ultrasonic wave propagating within the conduit in a backward direction, forward and backward ultrasonic wave signals generated by ultrasonic vibrating elements are sampled to derive forward and backward digital data series x and y, which are stored in a memory, the forward and backward digital data series x and y are read out of the first and second memory units and total sums of absolute difference values between the forward and backward digital data series x and y are calculated, while data positions of these backward and forward digital data series x and y are relatively shifted, a shift amount of data positions at which a total sum of absolute difference values becomes minimum is detected, an ultrasonic propagating time differe

Abstract: An ultrasonic flow rate measuring device for measuring the flow rate of a medium flowing through a line (1), with at least one ultrasonic transducer (2) and a guide frame (3) for guiding and holding the ultrasonic transducer (2). An electrical connecting box (12) which has a connection (13) for a cable (14) to the ultrasonic transducer (2) and a connection (15) for a cable (16) to the measuring device electronics is provided. Thus, in a clamp-on ultrasonic flow rate measuring device, simple cabling is achieved.

Abstract: An ultrasonic signal processing method for improving the signal-to-noise ratio in ultrasonic measurements comprises the transmission of a predefined timed sequence of a number of ultrasonic burst signals at a first transducer, and reception of a signal representing said transmitted sequence of ultrasonic burst signals at a second transducer. This signal is processed by addition of multiple time-shifted copies of the received signal to said original received signal to obtain a sum of the original received signal and its time-shifted copies. An original burst signal having an improved signal-to-noise ratio is reconstructed from this sum.

Abstract: The invention relates to an ultrasonic tomograph for spatial and temporal characterisation of fluids in motion such as air and water. This tomograph comprises a plurality of pairs of emitting-receiving ultrasonic probes, whereas each pair may be inscribed, diametrally opposite, on a circle centred round a flow axis of the fluid. The probes are therefore laid out on either side of the flow and will neither modify nor disturb the flow. Each probe may be displaced in a plane perpendicular to the flow axis. Indeed each probe is allocated a stepping motor. Each probe is a piezoelectric ceramic transducer which does not drift with time and which does not require any re-calibration, which provides the tomograph according to the invention stability over time. Moreover this tomograph is robust since these ultrasonic probes may be used under extreme conditions. The frequency of ultrasounds ranges between 30 kHz and 300 kHz.

Abstract: An acoustic flowmeter calibration method and sampling system address a variation in acoustic transducer delay time with increasing temperature. In one aspect, calibration of the path length between the sending and receiving transducers and calibration of the transducer delay time over a wide temperature range are optimized. In another aspect, the flowmeter output is temperature compensated based on the exhaust flowmeter gas temperature. These two aspects may be embodied in an ultrasonic flowmeter for exhaust gas measurement individually or in combination in accordance with the invention.

Abstract: An ultrasonic flowmeter of the present invention includes: first and second ultrasonic transducers that send and receive an ultrasonic wave and are arranged so as to form a propagation path for the ultrasonic wave in a flow path of fluid; a transmission unit and a reception unit that drive the first ultrasonic transducer and the second ultrasonic transducer such that the ultrasonic wave is sent and received in two ways between the first ultrasonic transducer and the second ultrasonic transducer, and receive the ultrasonic wave; a zero-cross detection unit that measures a propagation time of the ultrasonic wave by subjecting a received signal generated by the ultrasonic wave received in the reception unit to zero-cross detection; and a correction unit that reduces an error in the zero-cross detection caused by noise superimposed on the received signal, in which the ultrasonic flowmeter calculates a flow volume of the fluid on the basis of the propagation time.

Abstract: An ultrasonic flowmeter arranged to perform measurement with high accuracy has first and second ultrasonic transducers 1, 2 which transmit and receive ultrasonic waves, and which are placed so as to form a path for propagation of the ultrasonic waves in a flow passage 14 for a fluid, a transmitting section 3 which drives one of said first and second ultrasonic transducers 1, 2, a first matching section 5 which is connected to the transmitting section, and which adjusts the output impedance of the transmitting section, and a receiving section 6 which has an input impedance approximately equal to or lower than the adjusted output impedance, and which receives the ultrasonic wave reaching the other of the first and second ultrasonic transducers. The flow volume of the fluid is measured by detecting a bidirectional-propagation time difference between the ultrasonic waves propagating in the propagation path.

Abstract: An apparatus for measuring a gas concentration comprises a conduit through which an objective gas to be measured flows, a ultrasonic transmitting and receiving element fixed in a straight portion of the conduit and a reflecting plate fixed in the straight portion to face to the ultrasonic transmitting and receiving element. The apparatus further comprises a calibration gas source for supplying a calibration gas of which components and component ratio are preliminarily known, temperature sensors for measuring the temperature of the calibration gas flowing through the conduit, a propagation time calculating means for calculating the time period for propagation of the ultrasonic through the calibration gas in the conduit, a calibration means for calibrating the reference distance between the ultrasonic transmitting and receiving element and the reflecting plate based on the calculation results of the propagation time calculating means.

Abstract: An ultrasonic sensor having a pair of ultrasound transducers adapted to be inserted in and being able to perform at a single site of introduction into a duct. The ultrasonic sensor measures a forward ultrasonic path transit time and a second reverse ultrasonic path transit time of ultrasound signals propagating in a fluid. The arrangement being such that a comparison of the signal associated with ultrasound travel in one direction with that of the signal associated with ultrasound travel in the opposite direction enables the flow rate of the fluid in the duct to be determined. The ultrasonic sensor may utilize a reflecting surface on the duct and a reflective surface of an ultrasonic sensor end cap to provide forward and reverse ultrasonic W-shaped paths. In addition, the ultrasonic sensor may also be used to measure the temperature, viscosity, and cavitation effects of a fluid.

Abstract: An ultrasonic transducer assembly for helping monitor a fluid flowing through a duct is disclosed herein. The assembly includes: (1) a piezoelectric transducer element having a first contact surface electroplated with a first metallic film layer and an opposite second contact surface electroplated with a second metallic film layer; (2) a housing, configured on and at least partially conterminous with the outer surface of the duct, having a chamber in which the piezoelectric transducer element is situated and thereby substantially enclosed; and (3) means for conducting electrical signals between the electroplated first contact surface of the piezoelectric transducer element and the outside of the housing. In the assembly, the electroplated second contact surface of the piezoelectric transducer element is solder-mounted within the housing such that the piezoelectric transducer element is thereby coupled to the outer surface of the duct in a substantially conterminous fashion.

Abstract: A flow meter measures a flow rate of fluid flowing through a flow passage based on a duration of propagation of an ultrasonic wave along the flow passage. A signal of the received ultrasonic wave is then compared with a reference voltage to detect an arrival of the ultrasonic wave. A voltage setting unit determines the reference voltage to an appropriate level according to a signal output from a propagation measuring unit which measures a duration of propagation of the ultrasonic wave along the flow passage from the start of transmission of the ultrasonic wave to the output of a signal from a judging unit as the reference voltage being changed. The reference voltage is determined readily and accurately, the flow meter measures the flow rate with the appropriate reference voltage.

Abstract: Embodiments of the invention provide an algorithm for enhancing the transit time measurement of an ultrasonic wave through a fluid, and criteria for evaluating the suitability for various waveforms with regard to noise rejection. The transit time calculation provides a greater noise immunity and accuracy than techniques used in the prior art, and allows a measure of weighting of dispersed signals with different arrival times. The transit time calculation utilizes either the transmitted signal or the measurement of a reference system, the calculation of the squared convolution of this signal with the received signal, and the calculation of the transit time from the time-weighted squared convolution signal over a suitable interval defined by the minimums of the squared convolution signal. In the case of dispersion where the arrival times are symmetrically displaced around a mean transit time, or if asymmetric dispersion is suitably within the main lobe, the calculation properly weights the composite signal.

Abstract: An inductive flowmeter for measuring the flow velocity of a conductive fluid has an electrical circuit that advantageously utilizes minimal analog components, and hence has advantages over conventional systems. The circuit has an evaluation channel that measures a differential voltage induced across the fluid as it flows through a region having a magnetic field, and has a reference channel that provides a voltage indicative of the strength of the magnetic field. The differential voltage and the reference voltage are each digitized over the same time interval, and a programmable controller calculates a ratio of the digitized voltages to provide the flow velocity of the fluid.

Abstract: An apparatus and method for determining the density and fluid-type of a fluid flowing in a capillary tube, the velocity and viscosity of a blood sample flowing in a capillary tube, the erythrocyte sedimentation rate (ESR) of a blood sample after flow has been brought to an abrupt stop in a capillary tube, and/or the zeta sedimentation rate (ZSR) of a blood sample after flow has been brought to an abrupt stop in a capillary tube. These measurements are accomplished by directing a waveform pulse, such as an ultrasound pulse, at a pre-determined frequency transversely across the capillary tube and sample fluid, and by determining the flight of time of the pulse through the capillary tube and sample fluid and/or the Doppler shift of the echo signals reflecting off cells moving forwardly or transversely within a flowing, or stationary, blood sample.

Abstract: An flow rate measurement method and a ultrasonic flow meter is provided, which can measure a flow velocity accurately by utilizing a ultrasonic wave having a frequency by which a phase difference becomes zero. According to the flow rate measurement method, a reference ultrasonic velocity is prepared such that the fluid is in a standard condition, firstly. Then, an absolute ultrasonic velocity in the fluid and a temporary flow velocity V0 in the fluid are obtained. Then, the temporary flow velocity V0 is corrected by using the difference between the reference ultrasonic velocity and the absolute ultrasonic velocity thereby to determine an accurate flow velocity of the fluid, and to determine a flow rate of the fluid by using the accurate flow velocity and a cross section area of the conduit.

Abstract: A gas type identification system includes: a flow path; an ultrasonic measurement section disposed in the flow path, the ultrasonic measurement section including a pair of ultrasonic transducers; a sound velocity calculation section for calculating a sound velocity of a gas flowing through the flow path based on a signal from the ultrasonic measurement section; a sound velocity memory section for previously storing a predetermined sound velocity; and a comparison section for comparing the sound velocity calculated by the sound velocity calculation section with the predetermined sound velocity previously stored in the sound velocity memory section.

Abstract: Disclosed is a method and apparatus for measuring flow velocity and flow rate of a fluid in a tube member or the like with high precision. A flow vel0ocity measuring method has: a step of allowing a signal sound of ultrasound to propagate through a fluid in a tube member or the like and detecting a phase difference between the signal sound and an original signal; a step of eliminating a phase difference detected in the step to obtain synchronism; a step of detecting time or oscillation frequency required to complete the phase synchronization in the step; and a step of, on the basis of the time or oscillation frequency required to complete phase synchronization in the step, calculating flow velocity by referring to flow velocity which is preset in a table in correspondence with the time or frequency. In the table, flow velocities corresponding to changes in temperature, pressure, and kind of a fluid may be preset together with the time or oscillation frequency.

Abstract: An apparatus for determining fluid flow in a pipe. The apparatus includes an ultrasonic flowmeter adapted to be placed with the pipe for measuring fluid flow in the pipe. The apparatus includes a turbulence-reducing flow conditioner adapted to be disposed in the pipe through which the fluid flow in the pipe passes and upstream to the flowmeter. A turbulence-reducing flow conditioner for an ultrasonic flowmeter for a pipe. A method for determining fluid flow in a pipe. The method includes the steps of flowing the fluid in the pipe through a turbulence reducing flow conditioner wherein the conditioner reduces turbulence intensity T of the fluid and increases frequency of residual turbulence of the fluid after the fluid has passed through the conditioner. Then there is the step of measuring the fluid flow in the pipe with an ultrasonic flowmeter after the fluid flow has passed through the conditioner. A method for reducing turbulence in a pipe for measuring flow in the pipe.

Abstract: An apparatus for noninvasively monitoring the flow and/or the composition of a flowing liquid using ultrasound is described. The position of the resonance peaks for a fluid excited by a swept-frequency ultrasonic signal have been found to change frequency both in response to a change in composition and in response to a change in the flow velocity thereof. Additionally, the distance between successive resonance peaks does not change as a function of flow, but rather in response to a change in composition. Thus, a measurement of both parameters (resonance position and resonance spacing), once calibrated, permits the simultaneous determination of flow rate and composition using the apparatus and method of the present invention.

Abstract: A zero crossing detector has an analyzer which determines a zero level crossing of a currently input electrical pulse packet and which emits a trigger signal indicative of a determination having been made, and a pre-trigger unit which monitors variations in the amplitude of the current input pulse packet to detect a crossing of a pre-trigger level. The detector further includes a control unit operably connected to the pre-trigger unit which compares the amplitude of the pre-trigger level with any amplitude of a signal derived from the current or a previous input electrical pulse packet, and which automatically controls the amplitude of the pre-trigger level to maintain a working difference therebetween.

Abstract: An equipment specifying system of the present invention includes: a flow path for supplying gas to a plurality of pieces of equipment; an ultrasonic propagation signal measuring section for measuring a propagation signal based on a time during which an ultrasonic wave propagates across the flow path; a signal pattern generation section for generating a signal pattern based on a change in a propagation signal; a signal pattern storage section for previously storing a plurality of signal patterns respectively corresponding to a plurality of pieces of equipment; a signal pattern comparison section for comparing a signal pattern generated by the signal pattern generation section with a plurality of signal patterns previously stored in the signal pattern storage section; and an equipment specifying section for specifying currently used equipment among a plurality of pieces of equipment, in accordance with the comparison results obtained by the signal pattern comparison section.

Abstract: A low profile transducer (11, 12) is provided for use in flow meter for pipes of small diameter. The transducer (11, 12) has a transducer (18) or other form of transducer which transmits and receives electrical signals of three volts and 1 MHz and converts between these electrical signals and acoustic waves. In one embodiment, the transducer (18) produces surface acoustic waves (SAW), while in another embodiment the transducer (32) produces plate waves known as Lamb waves. These waves are converted to bulk acoustic waves (BAW) transmitted between the pair of transducers (11, 12).

Abstract: An ultrasound meter HAS a transmitter, a receiver and a control unit for the transmitter. To improve measurements a feedback connection proceeds between the control unit and the receiver for a signal from the receiver to the control unit, and the control unit regulates energy to the transmitter dependent on the signal fed back from the receiver so that a constant output signal is obtained from the receiver.

Abstract: The present invention provides an ultrasonic transducer having uniform characteristics. Because the characteristics of a pair of ultrasonic transducer are equalized with each other, measuring accuracy of an ultrasonic flowmeter can be improved. Electrical connection from an electrode surface 13 of a piezoelectric body 11 to an external electrode is achieved not by soldering but by an electroconductive elastic body 16. As a result, variations of the frequency characteristics due to thermal load on the piezoelectric body 11 can be reduced, and this makes it possible to obtain an ultrasonic transducer with uniform characteristics, and measuring accuracy of an ultrasonic flowmeter using a pair of the ultrasonic transducer can be improved.

Abstract: An ultrasonic-wave propagation time measuring method which enables determination of accurate propagation time, a gas-pressure measuring method, a gas-flow-rate measuring method, and a gas sensor. A reception wave which has been transmitted and received by an ultrasonic element 5 is shaped and integrated by an integration circuit 67 to obtain an integral value. A peak value of the integral value is held by a peak-hold circuit 39. As to detection of gas concentration, a resistance-voltage-division circuit 41 sets a reference value on the basis of the peak value, and a point in time when the integral value of the reception wave is judged by a comparator 43 to have reached the reference value is regarded as an arrival time. Subsequently, a gas concentration is detected on the basis of a period between the emission time and the arrival time.

Abstract: A process and device for measuring the velocity of flow of a fluid stream by measuring the difference between the respective traveltimes of acoustic pulses emitted by means of a generator (G) respectively between two points (PA, PB) spaced out along the fluid stream, according to whether they are propagated upstream or downstream in relation to the direction of flow, a difference that is indicative of the displacement velocity of the fluid stream. Measurement of this traveltime difference comprises using an acquisition unit (A) coupled to a processing unit (P) allowing determination of the frequency spectrum of each pulse and measurement of the phase lag affecting at least part of the frequency spectrum of each pulse, resulting from the traveltime thereof. Measurement of the velocity of flow of the fluid stream and of the resulting flow rate is very accurate. The process can be applied in chemical industries, chromatography, etc.

Abstract: A flow meter, such as a gas meter, for measuring the flow velocity and/or the volumetric through-flow of fluids. The flow meter has a body with connecting flanges for connecting the meter to a pipeline for the fluids. The meter has a tubular center piece that, on its exterior, has at least two receptacles, each of which receives a measuring device. The measuring devices are coupled to a signal processing unit. Electrical cabling between the measuring devices (probes) and the signal processing unit is completely covered against damage from the exterior by partially guiding the cables through bores in walls of the center piece of the flow meter and by covering portions of the cable and protruding sections of the probes with a cap.

Abstract: The invention provides a fluid meter comprising ultrasound transducers, attenuation means for attenuating parasitic ultrasound waves of wavelength &lgr;, and constituted by at least one passage in which said waves propagate along a main direction corresponding to a longitudinal dimension a of said passage, said passage having a transverse dimension b perpendicular to a and much smaller than the wavelength &lgr; of the parasitic waves in the propagation medium, said passage comprising a plurality of consecutive passage portions each having a part presenting a reduction in transverse propagation section along the dimension b of the passage, the longitudinal dimension of each passage portion being substantially equal to &lgr;/2.

Abstract: A liquid flow meter for directly measuring the velocity of a liquid is disclosed. The liquid flow meter includes a pair transducers arranged facing each other in a conduit through which the liquid flows. The liquid flow meter also includes a transmitter means for causing the transducers to simultaneously transmit an acoustic wave packet directed for reception at the other transducer. A differential receiver means is also included whereby the differential receiver means has inputs each coupled to a corresponding one of the transducers for detecting an acoustic signal received thereby and determining a difference between the two received signals. The difference being related to the velocity of the liquid within the conduit. The transmitter means and the differential receiver means are each matched to the transducers to ensure substantial reciprocity to thereby substantially avoid phase and/or amplitude variations in the received signal. A method for measuring the velocity of a liquid is also disclosed.

Abstract: A system for determining the density, flow velocity, and mass flow of a fluid comprising at least one sing-around circuit that determines the velocity of a signal in the fluid and that is correlatable to a database for the fluid. A system for determining flow velocity uses two of the inventive circuits with directional transmitters and receivers, one of which is set at an angle to the direction of flow that is different from the others.

Abstract: An ultrasonic gas meter housing member is configured to provide an associated multi-configuration ultrasonic gas meter assembly. The housing member is installable in an ultrasonic gas flow meter which includes an internal flow measurement tube along which gas travels for flow measurement, the tube having an inlet end and an outlet end. The ultrasonic gas meter housing member includes a closed back portion and a front portion spaced from the back portion to define a space for receiving the internal flow measurement tube such that the tube extends across the internal space of the housing member. At least one wall portion extends between the back portion and the front portion, the wall portion having a first opening and a second opening therethrough for connection of the housing member to a gas inlet pipe and a gas outlet pipe. The gas meter housing member is symmetrical about a plane which divides the housing member into a first portion and a second portion.

Abstract: It is an object of the present invention to provide an ultrasonic transducer, which is so configured as to reduce the variations in characteristics, thereby to enable the stabilization of the precision, as well as to enable the improvement of the durability, and the like, a method for manufacturing the ultrasonic transducer, and an ultrasonic flowmeter. In order to attain this object, in accordance with the present invention, the ultrasonic transducer is so configured as to include a piezoelectric element and an acoustic matching layer, wherein the acoustic matching layer is made of a dry gel of an inorganic oxide or an organic polymer, and a solid skeletal part of the dry gel has been rendered hydrophobic. With this configuration, it is possible to obtain the ultrasonic transducer having an acoustic matching layer 3 which is very lightweight and has a small acoustic impedance due to the solid skeletal part of the dry gel which has been rendered hydrophobic.