Endress + Hauser Gmbh + Co.

Endress U. Hauser Gmbh U. Co.

Other

Endress&plus;hauser Gmbh&plus;co.

Peter Gerst

Karlheinz Banholzer

Frank Hegner

Elke Maria Schmidt

Thomas Uehlin

Ulfert Drewes

Stefan Burger

Johanngeorg Otto

Wolfgang Lubcke

Rainer Martin

Peter Jung

Karl Flögel

Winfried Maier

Karl Fl&ouml;gel

Carsten Fitsch

Jean-Gyl Capt

Wulf Springhart

Jurgen Lau

A pressure sensor that is particularly suitable inter alia for the food industry and the measuring accuracy of which is stable over a long time, having a diaphragm seal () with a separating diaphragm () on which a pressure (P) to be measured acts and having a ceramic measuring cell () which is connected to the diaphragm seal () exclusively by inorganic materials, is provided, in which sensor the separating diaphragm () and all further sensor components coming into contact during measurement with a medium of which the pressure (P) is to be measured are metallic.

Pressure sensor having metallic diaphragm seal joint

A pressure sensor that is particularly suitable for the food industry and the measuring accuracy of which is stable over a long time, having a diaphragm seal with a separating diaphragm on which a pressure to be measured acts and having a ceramic measuring cell which is connected to the diaphragm seal exclusively by inorganic materials, is provided, in which sensor the separating diaphragm and all further sensor components coming into contact during measurement with a medium of which the pressure is to be measured are metallic.

Pressure sensor having metallic diaphragm seal mount

Measuring instrument having two pairs of lines connected to two indentical pairs of terminals, via which signal current flows through one pair and supply current flows through the other pair

Evaluation unit of a differential-pressure sensor An evaluation unit of a differential-pressure sensor is provided which supplies an output signal which corresponds to a differential pressure (.DELTA.P) which has been corrected with respect to a measuring error due to the static pressure (P.sub.S). The differential-pressure sensor has a capacitive single-chamber differential-pressure measuring cell with two capacitors (4, 5) as sensor element (1), and a temperature sensor (6) is arranged at the sensor element (1). The differential-pressure measured value is corrected by means of a first correction value (.DELTA.K) which is a measure of the static pressure (P.sub.S) at a reference temperature (T.sub.R). This correction value (.DELTA.K) is determined from the difference between a sensor temperature (T.sub.S) determined by means of the temperature sensor (6) and a sum of a temperature discrepancy (T.sub.0) and an internal temperature (T.sub.i) assigned to the sum (.SIGMA.) of the reciprocal values of the capacitances of the two capacitors (4, 5).

Evaluation unit of a differential-pressure sensor

For measuring the level of a material in a container on the basis of the radar principle, microwaves are radiated downwards and reflected microwaves received by means of the antenna of a ranging device arranged above the highest level anticipated. In the normal measuring operation the received microwaves are evaluated in the distance range up to empty distance corresponding to the distance of the antenna from the bottom of the container for determining the echo waves reflected from the surface of the material, for measuring the transit time of the echo waves and for computing the distance of the material surface from the antenna of the ranging device from the measured transit time. In order to reliably detect the empty condition of a container having a curved bottom, despite the multiple reflections of the microwaves reflected from the container bottom, when no echo waves are detected in the distance range up to the empty distance, the evaluation is done in an enlarged distance range and any echo waves detected in the enlarged distance range beyond the empty distance are assigned to the empty distance.

Radar-based method of measuring the level of a material in a container

A level measuring device using microwaves comprises an antenna for sending transmitted waves toward the surface of a material whose level is to be measured, and for the reception of echo waves resulting from reflection at the surface, and a receiving and evaluating circuit which derives from the echo waves received by the antenna an echo function representative of the echo amplitudes as a function of the distance and determines from the echo function the transit time of the microwaves from the antenna to the surface of the material and therefrom the distance of the surface of the material from the antenna. In order to detect the formation of deposits of the material on the antenna or further trouble conditions, such as damage to the antenna or the loss thereof, the level measuring device comprises an arrangement which compares a section of the echo function originating from a reference reflection point in the antenna or in the vicinity of the antenna with a predetermined threshold value and produces a signal indicating the existence of a state above or below the said threshold value. The reference reflection point may be constituted by a part of the antenna or a separate reference reflector mounted in the antenna or in the vicinity thereof.

Device for measuring a level of material using microwaves

Provision is made for a pressure sensor with a ceramic sensor element (1) which is introduced in a gas-tight manner, having a metallic housing (2) and having a metallic adapter (3) which is arranged between the sensor element (1) and housing (2) and which is connected in a gas-tight manner both to the housing (2) and to the sensor element (1).

Gas tight pressure sensor sealed with flexible metallic adaptor and

Radar-based method of level measurement

The differential pressure measuring apparatus comprises a single chamber differential pressure sensor having two resilient sensor diaphragms which enclose a volume filled with a fluid. In the single chamber differential pressure sensor two measuring capacitors are formed whose capacitances vary in opposite senses in response to the sensor differential pressure between the pressures acting on the two sensor diaphragms. The single chamber differential pressure sensor is connected to an adaptor comprising a volume filled with a fluid which is closed on the one hand by one of the two sensor diaphragms and on the other hand by an elastic adaptor diaphragm. An evaluation circuit calculates the sensor differential pressure from the capacitances of the measuring capacitors. The evaluation circuit comprises a first compensation arrangment which compensates the influences of the sensor temperature and of the sensor parameters on the calculated sensor differential pressure, and a second compensation arrangement which compensates the influences of the adaptor temperature and of the adaptor parameters on the sensor differential pressure corrected by the first compensation arrangement.

Differential pressure measuring apparatus

The differential pressure measuring apparatus comprises a single chamber differential pressure sensor filled with a fluid and having two measuring capacitors whose capacitances vary in opposite senses in response to the differential pressure to be measured and in the same sense in response to the temperature said capacitances being transformed by means of associated capacitance measuring circuits into measurement signals which are supplied to a calculation circuit for calculating the temperature and the differential pressure. A temperature measuring means which comprises a temperature sensor mounted on the differential pressure sensor and a temperature measuring circuit connected to the temperature sensor measures directly the temperature of the single chamber differential pressure sensor. A comparison means compares the temperature calculated from the capacitances of the measuring capacitors with the measured temperature and delivers a signal indicating the occurrence of a failure when the difference between the compared temperatures exceeds a predetermined threshold. By this self-monitoring, perturbations and other causes of failure which would result in an erroneous measurement can be recognized and indicated with great safety.

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Weil am Rhein, Germany

Peter Gerst