Scientific news from division 1

For very small static torques of up to 1 N·m, Working Group "Torque" has developed a standard facility which works according to the established principle – with a lever supported by an air bearing and load masses. The metrological investigations of this facility have recently been completed. These consisted in determining the quantities having an influence on the measurement result and in...

Erste Ergebnisse gravimetrischer Messungen des Oxidwachstums auf Siliziumkugeln bestätigen den theoretischen Verlauf und ermöglichen es, den Einfluss der Oxidbildung auf die Massestabilität von Siliziumkugeln abzuschätzen.

Bei der Nutzung von Messgeräten steht im Allgemeinen deren statische Übertragungscharakteristik im Vordergrund, welche bestimmungsgemäß im Idealfall durch einen linearen Zusammenhang zwischen zu messender Größe und Messanzeige definiert ist. In der Realität beinhaltet dieser Zusammenhang jedoch praktisch immer auch Nichtlinearitäten und muss deshalb individuell durch Kalibrierung bestimmt werden....

Laser Doppler anemometers (LDAs) in backscattering arrangement are used in many measuring devices as reference standards. An alternative calibration method, which is presented here, now also allows, for the first time, LDAs in forward scattering direction to be calibrated with small uncertainties.

Ultrasonic equipment, such as, e.g., ultrasonic cleaning baths, can cause very loud noise. High-frequency airborne ultrasound was measured up to 100 kHz on a solid metrological basis for the first time, and different assessment quantities were determined quantitatively.

The sound power is the major descriptor for the total amount of the sound radiated from a source. In contrary to the acoustic field quantities like sound pressure, it is independent of the acoustic environment and of the distance to the source. The acoustic properties of technical products e.g. a sound emission or a sound insulation, are therefore described in terms of sound power or quantities...

A scaled reverberation room has been successfully used for the primary calibration of diffuse-field microphones at PTB.

With a susceptometer both the volume magnetic susceptibility and the vertical component of the permanent magnetic polarization of a weight can be tested. Monte Carlo simulations of the susceptometer method were performed to evaluate the expanded measurement uncertainties of the magnetic properties for comparison measurements and intercomparisons.

Im Jahre 1960 entdeckten die beiden US-Amerikaner Woodside und Messmer, dass ein mit Gas in seinen Poren gesättigter Sandstein die Wärme schlechter transportiert als derselbe mit einer Flüssigkeit gesättigte Stein, obwohl beide Füllfluide die gleiche Wärmeleitfähigkeit besitzen. Bisher war man der Ansicht, dass der Knudsen-Effekt dieses Phänomen verursacht. Er tritt auf in Poren, die kleiner sind...

Acoustic signals are analyzed with the aid of sound level meters, using so-called filter banks. These must be investigated with respect to their real-time capability. For this purpose, test signals are used which must in turn fulfill specific conditions. A new procedure for the testing of test signals for the real-time testing of filters can help to avoid incorrect test results.

In the scope of the characterization of the dynamic behaviour of this calibration device with a mounted force transducer, different experimental measurements were carried out and the strongest modal oscillations were identified. Using the example of a heavy force transducer of 25 kg, the observed modal behaviour was confirmed by finite element modelling. Further experiments showed that the...

For the release quantity of methane through the exhaust flow of a biogas upgrading facility a mobile measuring system was successfully launched. In place stored measuring data of the flow and methane concentration measurement at the exhaust flow is sent via remote data transmission to PTB. With that collected data and the data of the product gas, which is measured by calibrated meters, a balance...

Ein von der PTB konzipierter Gasdurchflussprüfstand für hohe Betriebstemperaturen wurde erfolgreich in Betrieb genommen und dem PTB-Kuratorium auf dessen diesjähriger Tagung vorgestellt. Der Prüfstand eignet sich für die Prüfung und Kalibrierung sowie wissenschaftliche Untersuchung von Gasdurchflussmessgeräten in einem Temperaturbereich von 20 °C bis 600 °C.

Within the scope of European harmonization, standard DIN 4109 "Sound insulation in buildings" is at present being fundamentally revised. This standard contains a "Component Catalogue" which was provided by the supreme construction control board and indicates, for all common constructions and components, sound insulation values which may be used without individual testing to furnish proof of...

Torque wrenches are, among other things, used to tighten wheel nuts and screws on a car. Thereby, the torque is specified by the manufacturer of a vehicle. These wrenches are available in a triggering version ("setting torque wrenche") and, to an ever increasing extent, they are also put on the market as indicating wrenches with an electronic display. For the calibration of these measuring...

Sander Sandstein ist benannt nach seiner Herkunft, der Stadt Sand am Main. Wie andere Sandsteine auch, wird er nicht mehr nur zur Restaurierung von Gebäuden (z. B. Reichstag) verwendet, sondern auch wieder für Neubauten, gilt er doch als natürliches Baumaterial. Aufgrund seiner porösen Struktur leitet der luftgesättigte Sandstein die Wärme relativ schlecht, was Heizenergie einsparen lässt. Und...

Ultrasonic baths have long been widely used in industry and trade. Despite this, no uniform procedure has existed so far to compare the cleaning results obtained by different devices or the cleaning effectivity of a device in various operating modes. PTB has developed a procedure which allows the abrasion of particles from a surface – hence a cleaning process – to be measured directly.

In Germany, the Physikalisch-Technische Bundesanstalt (PTB), as a Notified Body, is in charge of the serial testing of powder-actuated captive-bolt pistols in accordance with Machinery Directive 2006/42/EC exclusively under the aspect of safety at work. Each year, initial or repeated testing is carried out for up to ten designs for the European market alone. Due to the high failure rates of such...

Vertreter der Waagenindustrie, von Produzenten von Wägezellen und der PTB diskutierten im Juni 2013 Vorschläge zur Anpassung des WELMEC Leitfadens 2.4 „Wägezellen“ an das im WELMEC Leitfaden 8.8 beschriebene „Modulare Konzept“.

Im September 2013 fand eine Begutachtung zur Anerkennung von Herstellerprüflaboratorien im Rahmen der OIML Vereinbarung zur gegenseitigen Anerkennung von Zertifikaten (OIML MAA) auf dem Gebiet der nichtselbsttätigen Waagen statt. Die Ergebnisse der Begutachtung stimmen vorsichtig optimistisch, dass eine Aufnahme der auditierten Herstellerlaboratorien in die Liste der Prüflaboratorien für das DoMC...

Traffic-monitoring systems (TMS) made by the VIDIT company and approved by PTB are used for video-based distance and speed measurements of vehicles. Within the scope of a joint cooperation with the approval holder and the DTC company, the measurement error of the traffic-monitoring system has, for the first time, been determined under the conditions of real driving manoeuvres.

Storage tanks are, in addition to their function of storing liquids, usually used also for the measurement of the stored amount of liquid. The determination of the volume of liquid by means of level measurement and a corresponding geometric capacity table - often called a “dipping table” - is relatively well protected by numerous standards and regulations. Due to the thermal expansion caused by...

In certain frequency ranges, disturbing sound waves cannot be damped with conventional absorbers. An optimization procedure and the use of finely tuned resonators, which are correspondingly dimensioned and positioned in the room, allow different damping effects to be achieved.

Vom 8. bis 10. Oktober 2013 fand die 48. Sitzung des Internationalen Komitees für das gesetzliche Messwesen (CIML) in Ho Chi Minh City, Vietnam, statt. Insgesamt nahmen 144 Delegierte aus 40 Mitgliedstaaten und 11 korrespondierenden Mitgliedstaaten teil. Die wichtigsten Entscheidungen und Entwicklungen werden vorgestellt.

In numerous industrial applications, the demand for the traceability of large forces is increasing. Hereby, different influence quantities have to be taken into account in order to attain the smallest possible measurement uncertainties. Force measurement in the meganewton range is to be improved within the scope of a European research project.

Vergleiche von Flüssigkeits-Primäranlagen sind stets mit einer Reihe von Besonderheiten verbunden, die vor allem hohe Anforderungen an die zu verwendenden Vergleichsnormale stellen. Einerseits wachsen auf Grund der zunehmenden wirtschaftlichen Bedeutung von Flüssigkeitsmessungen die Ansprüche an die Messgenauigkeit, so dass stationäre Normalanlagen mit immer kleineren Messunsicherheiten von...