Abstract: For flow rate measurement by means of ultrasonic waves, on a measuring tube two ultrasonic transducers are arranged spaced apart from each other, one operating as transmitting transducer and the other as receiving transducer. For determining the flow rate the phase shift between the transmission signal and the reception signal is measured digitally in that the measuring time intervals corresponding to the phase shift the periods of a signal are counted with a counting frequency which is substantially greater than the frequency of the transmission signal. The start phase which the counting frequency signal has at the beginning of each counting operation with respect to the measuring time interval is varied from measuring time interval to measuring time interval in a measuring cycle including a plurality of successive measuring time intervals and the counts obtained in the course of the measuring cycle are evaluated to form a measured value with increased measurement resolution.

Abstract: The mass flow meter operating by the Coriolis principle comprises a mechanical oscillating system having at least one measuring tube and an optical sensor means for sensing the mechanical oscillations of the oscillating system. The optical sensor means includes a light transmitter, a light receiver and an optical waveguide means having two quartz or sapphire rods which transmit the light of the light transmitter to the light receiver, the transmitted light flux being influenced by the oscillations of the mechanical oscillating system. To increase the mechanical strength and to protect the quartz or sapphire rods against temperature influences and against chemically aggressive media, the quartz or sapphire rods are embedded in ceramic material or glass which, preferably, is further surrounded by a metal cladding.

Abstract: In the method for mass flow measurement by the Coriolis principle a fluid-traversed elastically deformable measuring tube is periodically deflected. As a measure of the mass flow phase displacements are measured between deflections of portions of the measuring tube wall which are arranged differently in the flow direction. For this purpose a periodic deformation of the cross-section of the measuring tube is effected in such a manner that portions of the measuring tube wall lying diametrically opposite each other are deflected in each case through about the same distance in opposite or the same direction transversely of the flow direction of the fluid. This method can be carried out with a simply constructed mass flow meter in the operation of which a wandering of the center of gravity of the meter is substantially avoided and which is also suitable for large nominal widths.

Abstract: In an electromagnetic flow measuring arrangement an electrically conductive fluid flows through a measuring tube in which a magnetic field is generated transversely of the flow direction, whereby a voltage is induced which is proportional to the flow velocity. This voltage is tapped by means of two electrodes. The cavity of the measuring tube has an elliptical cross-section with two major axes, the first major axis coinciding with the connecting line of the two electrodes, and the second major axis coinciding with the direction of the magnetic field. The flow to be measured is proportional to the product of the measured flow velocity and the cross-section area of the cavity of the measuring tube. The flow measuring arrangement is constructed so that on changes of the cavity cross-section caused by external influences the cross-section retains substantially the profile of an ellipse and the length of the second major axis remains substantially constant.

Abstract: The vortex frequency flow meter has a tube body which comprises a flow passage for the medium of which the flow is to be measured. In the flow passage a bluff body is arranged which generates Karman vortices of which the recurrence frequency is proportional to the flow velocity of the medium. A sensor which responds to the pressure fluctuations generated by the vortices is arranged in a cavity which communicates via passages with the flow passage so that the pressure fluctuations are conveyed to the cavity. The passages can be closed by a shutoff member which is adjustable from outside by an actuating member. It is thus possible to remove the sensor from the cavity after the closure of the passages without the flow medium being able to emerge.

Abstract: An arrangement for generating natural resonant oscillations of a mechanical oscillating system includes an electromechanical oscillation exciter which on excitation by an electrical excitation signal generates a drive force setting the oscillating system in mechanical oscillations, an oscillation sensor which is formed as displacement sensor and senses the mechanical oscillations of the oscillating system and converts them to an electrical sensor signal, and an excitation circuit which receives the sensor signal and supplies to the oscillation exciter the electrical excitation signal with the frequency of the sensor signal. The excitation circuit includes a phase control circuit which controls the phase position of the excitation signal in dependence upon the phase position of the sensor signal. A phase shift circuit produces a phase displacement of 90.degree.

Abstract: A mass flow meter operating by the Coriolis principle includes a mechanical oscillating system having two straight measuring tubes which are clamped at both ends. In the center of the measuring tubes an oscillation exciter is disposed which sets the two measuring tubes into oppositely phased flexural oscillations. The mechanical oscillations are sensed by oscillation sensors which are arranged at equal distances on both sides of the oscillation exciter. The phase displacement of the sensed oscillations is a measure of the mass flow. The mechanical oscillating system is arranged axially in a support tube. For decoupling the mechanical oscillations from the support tube the mechanical oscillating system is freely suspended in the support tube at each end by an annular diaphragm. The entire mechanical oscillating system including the diaphragms preferably consists of titanium.

Abstract: A mass flow meter operating by the Coriolis principle comprises a mechanical oscillating system having two straight measuring tubes which are clamped at both ends. The mechanical oscillating system is arranged axially in a support tube. In the center of the measuring tubes an oscillation exciter is disposed which sets the two measuring tubes into oppositely phased flexural oscillations. Oscillation sensors sensing the mechanical oscillations at equal distances on both sides of the oscillation exciter generate electrical oscillation sensor signals which are characteristic of the frequency and phase position of the sensed oscillations. An evaluation circuit receives the oscillation sensor signals and generates from their phase difference a measuring signal indicating the measured value of the mass flow. A first temperature sensor is arranged such that it measures the temperature of the support tube and generates a first temperature sensor signal indicating said temperature.

Abstract: A capacitance measuring circuit operating by the principle of switched capacitors includes a switchover device which alternately and periodically with a predetermined switchover frequency connects the measured capacitance for charging to a constant voltage and for discharging to a storage capacitor whose capacitance is large compared with the measured capacitance and whose terminal voltage is held substantially at a constant reference potential by a controlled discharge current. The magnitude of the discharge current is then proportional to the measured capacity and represents the measured value. A further switchover device applies a shield associated with the measured capacitance with the switchover frequency periodically and alternately to potentials which correspond substantially to the constant voltage and reference potential respectively. As a result, the potential of the shield is caused to follow the potential of the electrode to be shielded in accordance with the principle of "active shielding".

Abstract: A vortex flow meter for measuring the flow velocity of a fluid in a conduit includes a bluff body disposed in the flow passage of the conduit. The bluff body generates Karman vortices whose recurrence frequency is characteristic of the flow velocity to be measured. In the bluff body a cavity is formed which via passages communicates with the flow passage of the conduit and in the cavity a capacitive vortex sensor is disposed which converts the vortex pressure fluctuations originating from the Karman vortices to capacitance changes. The capacitive vortex sensor includes a first oscillating body in the form of a sensor sleeve which is deflectable by the vortex pressure fluctuations and an electrode holder which is disposed in the sensor sleeve and is formed as second oscillating body but is uncoupled from the vortex pressure fluctuations.

Abstract: In magnetic-inductive flow measurement with periodically reverse-poled DC magnetic field (with or without field-free phases) the signal voltage in each half period is sampled during a measuring signal sampling interval and the signal value obtained by the sampling is stored. For compensating an interference DC voltage superimposed on the measuring signal in a compensation interval following each measuring signal sampling interval within the same half period by sampling and storing the signal voltage a compensation voltage is generated which compensates the signal voltage within the compensation interval to the value zero. The compensation voltage is stored and superimposed on the signal voltage until the next compensation interval. During a correction sampling interval following each compensation interval within the same half period the signal voltage is again sampled and the signal value thereby obtained also stored.

Abstract: An arrangement for magnetic-inductive flow measurement of an electrically conductive liquid flowing in a conduit includes a magnetic field generator which generates a periodically reversed magnetic field passing through the conduit perpendicularly to the flow direction. In the conduit two electrodes are disposed. The voltage taken from the electrodes is applied to a measuring amplifier. Connected to the output of the measuring amplifier are two sample and hold circuits which are controlled by a control circuit in such a manner that they sample the output voltage of the measuring amplifier for equal induction values of opposite sign of the magnetic field and store the sampling values until the next sampling. A subtraction circuit forms the difference of the stored sampling values.

Abstract: An arrangement for generating DC magnetic fields of alternating polarity for the magnetic-inductive flow measurement by means of a field coil which is connected via alternately controlled switching members to a DC voltage source, wherein during the reversal time following the change-over of the switching members a capacitor is connected to the field coil to form a resonant circuit separate from the DC voltage source and the capacitance C of the capacitor in dependence upon the desired reversal time .DELTA.t has substantially the value ##EQU1## wherein L is the inductance and R the ohmic resistance of the field coil.

Abstract: A method of compensating interference DC voltages in the electrode circuit in magnetic-conductive flow measurement with periodically reversed DC magnetic field in which the useful signal is obtained by sampling and storing the signal voltage after each reversal of the magnetic field at opposite polarity values of the magnetic field during a sampling time interval and forming the difference of the stored sampled values, and wherein in a compensating time interval following each sampling time interval a compensation voltage is produced by sampling and storing the signal voltage, which compensation voltage is superimposed oppositely on the signal voltage for compensating the signal voltage within the compensation time interval to the value zero and is retained until the next compensation time interval, wherein each compensation time interval lies within the time interval corresponding to the switched-on magnetic field, in which also the preceding sampling time interval lies.

Abstract: Method and apparatus for inductive flow measurement using a periodically reversed magnetic field, in which the useful signal is obtained by sampling and storing the signal voltage at equal but opposite values of induction of magnetic field and forming the difference of the stored sample values. There is formed between each two successive magnetic field impulses of opposite polarity an interval where the magnetic field is zero, there being generated in a compensation time interval within each magnetic field interval at the same time-interval before the next subsequent sampling of the signal voltage, a compensation voltage which restores the signal voltage during the compensation time interval to zero value. The compensation voltage value developed during the compensation time interval is stored and is employed until the next compensation time interval.