Proceedings

TRUST BUT VERIFY – PRACTICAL APPROACHES TO HUMIDITY GENERATION AND MEASUREMENT

Construction of humidity generators is a common undertaking in many of today's national metrology institutes and commercial calibration laboratories. A generator based on theoretical methods and statistical uncertainty expectations is often trusted as a laboratories primary humidity reference. While it is important to follow sound design theory, and compute statistical estimates of the output from a generator, verification is an equally powerful tool that can help to make even the weakest of designs more trustworthy. Generator designs will be reviewed in an effort to avoid common obstacles...

THE REALIZATION AND THE DISSEMINATION OF THE DETECTOR-BASED KELVIN

In the International Temperature Scale of 1990 (ITS-90), temperatures above the freezing temperature of silver are determined with radiation thermometers calibrated using spectral radiance ratios to one of the Ag-, Au- or Cu-freezing temperature blackbodies and the Planck radiance law. However, due to the use of spectral radiance rats, the temperature uncertainties of the ITS-90 increase as the square of the temperature ratios. Recent acoustic- gas thermometry measurements have also shown that the underlying thermodynamic temperatures used in the radiance ratios in determining the Ag- and...

TEMPERATURE AMPLIFIER BY MEANS OF COUPLED GAS-CONTROLLED HEAT-PIPES

BNM-INM and IMGC-CNR have been working during many years in the field of Gas-Controlled Heat-Pipes (GCHPs). These devices have been specifically developed for accurate temperature measurements, with ever improving thermal characteristics during the last 30 years. A GCHP is based on the thermodynamic properties of the liquid-vapor transition of a given working fluid under a controlled pressure. The measuring zones of the more recent GCHPs, connected to an accurate pressure controlled line, present a temperature uniformity and stability at the millikelvin level in a very large range of...

TOWARDS A NEW DEFINITION OF THE KELVIN: WAYS TO GO

The present definition of the kelvin links the unit of temperature with a material property. It would be more consistent with the current approaches to other base units to fix the value of the Boltzmann constant k , in- stead. For this purpose, k must first be determined with distinctly lower uncertainty. This paper considers ex- perimental methods having potential to contribute to the determination of k .

Temperature Scales from the early days of thermometry to the 21 century

50 kNm TORQUE STANDARD MACHINE

The paper introduces the working principle of dead-weight balance type 50kNm torque standard machine , which was developed recently. The paper describes in detail the key technique , etc. such as the knife edge supporting technique with high load , the force magnifing technique , the alignment technique and the computer control automatic loading technique , etc. The paper analyses the uncertainty of the machine and the compared and verifyed data with LNE . The uncertainty of the 50kNm torque standard machine arrives at 0.023%(tp=3.1).

PTB's 'new' 2 MN Deadweight Force Standard Machine

In this contribution, the new 2 MN deadweight force standard machine of PTB, which was moved from Berlin to Braunschweig and has been completely modernised, is presented. The determination of the mass of the deadweights with a special mass comparator is described. The uncertainty of the machine is theoretically analysed and experimentally verified by force measurement procedures.

UNCERTAINTY AND INTERPOLATION

This article deals with interpolation methods, ways to determine which method is required and ways to check the results’ fitness.

The calibration system of force measurement devices - conceptions and principles

Developed, put into practice and used the universal automatic system MABA-2000 for calibration of force measurement devices in accordance to ISO 376-1999, ISO 7500-1999 and manufacturer requirements. The system includes a set of load cells from 1 kN to 5 MN, amplifier DMP-40 (HBM), computer and accessories. Mathematically proved the possibility of calibration in points, which vary from series to series, proved, and confirmed the application of calculation of formulas accuracy deviation and repeatability in accordance to ISO 7500-1999. This approach increases the productivity and simplifies...

SIM FORCE STANDARDS COMPARISON UP TO 10 kN

A comparison in the quantity of force was carried out among the SIM national laboratories in order to estimate the level of agreement for the realization of the quantity and the uncertainty associated to its measurement. This comparison was carried out up to 10 kN. The equipment used consisted on two force transducers (load cells); both with the same measuring range (10 kN). With the purpose of obtaining maximum accuracy on the transducers, the comparison range was selected from 4 kN up to 10 kN. This comparison provides a link to CIPM Key Comparisons. The results obtained, as well as the...