The invention provides a method and apparatus for checking the condition of a self-oscillating vibrating fork level switch. The switch includes a test facility that operates when the switch is taken from a closed loop feedback operating mode into an open loop test mode. Amplitudes of the received test signals are subjected to comparison with predetermined thresholds to establish the health of the switch.

A purging attachment for a workpiece having a surface to be processed using laser radiation, wherein the workpiece has a chamber open on at least one side of the workpiece, and wherein the surface is within the chamber, comprises: a central opening through the purging attachment; a purge gas supply channel extending through the purging attachment to an outlet opening; a purge gas suction channel extending through the purging attachment to an inlet opening, wherein the outlet opening of the purge gas supply channel and the inlet opening of the purge gas suction channel are arranged on opposite sides of the central opening; and a centering portion configured to interact with a centering region arranged on the side of the workpiece such that the central opening, the outlet opening, and the inlet opening communicate with the chamber.

The present disclosure relates to a method for determining a process variable of a medium by means of a vibronic sensor. In a first operating mode, an oscillatable unit is excited by a first electrical excitation signal, such that it executes mechanical oscillations, and the mechanical oscillations of the mechanically oscillatable unit are received and converted into a first electrical, received signal having a first frequency. Furthermore, the first received signal is evaluated relative to the process variable. In a second operating mode, mechanical oscillations of the oscillatable unit are received and converted into a second electrical, received signal, wherein a second frequency of the second electrical, received signal is ascertained, and wherein the second frequency is associated with a first disturbing influence for the vibronic sensor. Furthermore, the present disclosure relates to an apparatus, which is suitable for performing a method of the present disclosure.

A method for determining and/or monitoring a predeterminable fill level of a medium in a container using a vibronic sensor having at least one sensor unit with a mechanically vibratable unit, comprises exciting the mechanically vibratable unit with an excitation signal to produce mechanical vibrations, and receiving the mechanical vibrations in the form of a reception signal, determining an amplitude and a frequency of the reception signal, comparing the frequency and amplitude of the reception signal with a predeterminable frequency limit value and a predeterminable amplitude limit value, and determining a reaching of the predeterminable fill level on the basis of the comparison.

An assembly arrangement for connecting a membrane of a vibration sensor with a drive unit such that vibrations of the drive unit are transmitted to the membrane and vibrations of the membrane are transferred to the drive unit, wherein the assembly arrangement is formed as a cylindrical sleeve, having on one end a fastening section for indirectly or directly fastening to the membrane or an element connected with the membrane, and an insertion opening for the drive unit on the other end.

An apparatus and a method for determining and/or monitoring at least one process variable of a medium in a container, comprising: a mechanically oscillatable unit, a driving/receiving unit for exciting the mechanically oscillatable unit to execute mechanical oscillations by means of an electrical exciting signal and for receiving and transducing mechanical oscillations into an electrical, received signal, an electronics unit, which electronics unit is embodied, to produce the exciting signal starting from the received signal, to set a predeterminable phase shift () between the exciting signal and the received signal, and from the received signal, to determine and/or to monitor the at least one process variable. A phase correction unit is provided, which phase correction unit is at least embodied, to ascertain a phase correction value (.sub.kor) from at least one process parameter dependent, characteristic variable of at least one component of the apparatus, especially the driving/receiving unit, and to set the predeterminable phase shift () in accordance with the phase correction value (.sub.kor).

The present disclosure includes a method for monitoring the condition of a component of an electromechanical resonator having a piezoelectrical element which can be excited to mechanical vibration using an electrical excitation signal and the mechanical vibrations of which can be received in the form of an incoming electrical signal. The method steps performed at a first point and a second point in time, including determining an amplification factor of the electromechanical resonator, determining a mechanical quality resonator, and establishing an electromechanical efficiency resonator at least from the amplification factor and the mechanical quality. A change over time in the electromechanical efficiency is calculated from the first point to the second point in time, the change over time in the electromechanical efficiency is compared with a pre-definable threshold, and a condition indicator is determined from the comparison.

An apparatus for determining and/or monitoring the viscosity, the density and/or a predetermined filling level, having an excitation/receiving unit which excites a mechanically vibratable unit to vibrate, wherein a control/evaluation unit which is connected to the excitation/receiving unit and has a measuring branch and a checking branch separate from the latter is provided. The checking branch is configured to apply an excitation signal to the excitation/receiving unit, to receive the vibrations of the mechanically vibratable unit and to determine at least a first malfunction and a second different malfunction of the mechanically vibratable unit and/or of the excitation/receiving unit from the received vibrations, wherein the excitation signal of the checking branch has a continuous changing frequency which is described by a frequency/time function and passes through a plurality of modes of the mechanically vibratable unit.

A system for determining the level of solids accumulated in a sand separator has a vibratory level sensor and a solid separator control system. The vibratory level sensor includes a vibratory rod and an exciter connected to the vibratory rod. In some embodiments, a vibration sensor is connected to the vibratory rod to monitor changes in the vibration of the rod. In other embodiments, changes in vibration are measured by looking at the rotational speed and power inputs at the exciter.

The fluid-level sensor has an acoustic waveguide comprising a flexible metal rod, an electroacoustic transducer coupled to one end of the acoustic waveguide and an acoustic resonator coupled to the other end of the acoustic waveguide. The flexible metal rod has two ends, one cylindrical waveguide coupled via a conical acoustic concentrator to one end of the flexible metal rod, the other cylindrical waveguide coupled via a conical concentrator to the other end of the flexible metal rod. One cylindrical waveguide is coupled to the electroacoustic transducer and the other cylindrical waveguide is coupled to the acoustic resonator. The structure provides for the enhanced functional capabilities of the sensor by using it under the conditions of high temperature, radiation, strong electromagnetic interference, intense vibrations, impacts, and other negative factors. The sensor can be installed, maintained, and repaired without hazard to servicing personnel.