IMEKO Event Proceedings

Author(s)
Title (as link)
Abstract
Event

J. Setina, J. Tesar, Z. Krajicek
Validation of a variable bell jar pressure as a method for primary generation of absolute pressure in the range from 100 Pa to 5 kPa
Generation of absolute pressure with a pressure balance is commonly done by enclosing the space above weights with a bell jar and evacuating it with a vacuum pump. Residual pressure in a bell jar is usually of the order of few tens of Pa to few Pa, depending on the effective pumping speed. Its value is added to a calculated pressure of the gravitational force of the piston and weights to obtain the generated absolute pressure. By connecting to the absolute pressure balance a precise and stable pressure gauge with sufficient resolution it is easy to observe that small changes of residual pressure in a bell jar generate a corresponding change in a pressure reading of the gauge. Unfortunately the lowest absolute pressure which can be generated by a pressure balance of conventional design is determined by the tare weight of the piston and some small additional weights necessary for sufficient minimum free rotation time and it is in the pressure range starting at 3 kPa and up to 5 kPa.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

J. C. Torres-Guzmán, L. H. Paraguassú, P. R. G. Couto, I. L. Bezerra
SIM vacuum comparison from 133.3 Pa to 13.33 kPa
This comparison constitutes the second part of the first vacuum comparison among National Metrology Institutes (NMI) within the Interamerican Metrology System (SIM). Each laboratory used its national standards for the compared range. The Centro Nacional de Metrología (CENAM, Mexico) used a reference standard (comparison system type) and the Instituto Nacional de Metrologia, Normalização e Qualidade Industrial (INMETRO, Brazil) used a similar reference standard (comparison system type). The comparison started in December 2004 and finished in March 2005. The objective of the comparison was to estimate the level of agreement for the realization of the quantity and the uncertainty associated to its measurement.
One transducer (Capacitive Diaphragm Gauge) was used as transfer standard; the comparison range was selected from 133.3 Pa up to 13.33 kPa. The relevant aspects of the measurement protocol are summarized in the paper but were widely developed in the comparison reference documents. The gas used for the comparison was nitrogen. The measurements started at the lowest pressure and the pressure was increased up to the maximum range. The analysis of measurements comparability between the laboratories is included here. This bilateral comparison has been entered within the SIM data base as a pilot comparison SIM.7.26 P.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

A. Navarro-Nateras, J. C. Torres-Guzman, P. Olvera-Arana
Measurement systems development for the calibration of leaks and holes in dynamic pressure (microflow) at CENAM, Mexico
The pressure and vacuum group of the Force and Pressure Division, at the Centro Nacional de Metrologia (CENAM, Mexico) has developed two measurement systems for calibration, one for leaks and another for holes in dynamic pressure.
The leaks calibration system is based on the method of pressure increment at constant volume (and constant temperature) within the measurement range starting at 1 x 10-6 Pa·m³·s^-1 up to 5 Pa·m3·s^-1 with volumes of 0.5 L or 1 L (according to the leak range to be calibrated), with an operation pressure from 1 x 10^-5 Pa up to 130 kPa, using helium, nitrogen or air as manometric fluids.
For the calibration of holes in dynamic pressure, the method PVTt is used. This is, pressure increments at constant volume and constant temperature during a given time. The volume used is 3.75 L with a gas flow up to 20 cm³·min^-1 using nitrogen as operation fluid.
The procedure of holes calibration consists on measuring the flow through a small hole by measuring the pressure increment due to the gas accumulation in a known volume during a period of time with controlled temperature conditions. The PVTt system is formed by pressure gauges, a gas collection tank with a known volume, temperature sensors, a chronometer for time measurement, a vacuum pump, a set of valves to control the gas flow direction and the hole which will be calibrated.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

Z. Krajicek, D. Prazak, J. Tesar, M. Vicar, T. Hajduk
Standardization of negative gauge pressures using piston balances
Standardization of negative gauge pressures is a peripheral branch of pressure metrology, but this approach is unfair. Although this pressure mode can be ensured simply by liquid columns, the utilization of pressure balances in this area brings many technically interesting solutions. They include an inverse piston-cylinder design (it is the basis of most commercial solutions), a classical pressure balance with generation of negative gauge pressure under a bell jar, a digital piston manometer and a pressure divider designed for absolute pressure mode.
The paper focuses on the methods utilized in the Czech Metrology Institute, i. e. the generation of negative gauge pressure under a bell jar and, newly, the use of the absolute pressure divider and also a digital non-rotating-piston manometer for the range of very low negative gauge pressures that are very hard to reach by other methods.
The paper introduces their principles, ways of ensuring their metrological traceability, the detailed analyses of their uncertainty budgets, practical experiences and the results of their mutual experimental comparison. Furthermore, there are described methodologies of calibration of the secondary standards of negative gauge pressure. Finally, all the methods are compared from the viewpoints of the uncertainties that can be reached and the suitability of each standard for practical calibrations.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

S. Zuñiga-Gonzalez, P. Olvera-Arana, J. C. Torres-Guzman, F. J. Flores-Martinez Oral Presentation (Pressure)
Pneumatic gauge pressure proficiency test in the range from -70 kPa to 0 kPa for Mexican accredited laboratories
With the purpose to establish deviations and concordance levels for negative pressure measurements in Mexico, and by a request from the Mexican Accreditation Body (ema), the pressure and vacuum group in CENAM (the Mexican National Metrology Institute) organized a proficiency test among laboratories from the National System of Calibrations (SNC). In this proficiency test most of the Mexican secondary laboratories with the capabilities to perform calibrations in this measurement range participated.
This document presents the results and the concordance level obtained among the laboratories which participated in the proficiency test. The measurements performed by the pilot laboratory (CENAM) are also presented. CENAM established the reference values (error and uncertainty) and determined the drift of the transfer standard during the period of the proficiency test.
The concordance of the results obtained by the laboratories was evaluated by means of the normalized error equation method.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

P. Olvera-Arana, J. C. Torres-Guzman, A. Navarro-Nateras, J. Aranzolo-Suárez
Hydraulic gauge pressure proficiency test in the range from 7 MPa to 70 MPa for Mexican accredited laboratories
At the end of 2006, the Pressure Group of the Centro Nacional de Metrología CENAM, Mexican National Metrology Institute, organized and piloted a proficiency test in hydraulic gauge pressure in the range from 7 MPa to 70 MPa for accredited laboratories by the Entidad Mexicana de Acreditación (ema), Mexican Accreditation Body. For the proficiency test, the pilot laboratory (CENAM) carried out three calibrations of the transfer standard; the first one at the beginning of the proficiency test, the second at the middle and the last one at the end of the program. With the measurements made by CENAM the reference values were established, including error and uncertainty. The deviations for each laboratory were compared against the reference values and the compatibility of results was calculated, for each participating laboratory, by means of the normalized error equation method. The measurements were carried out by each participant laboratory with their own resources (personnel, calibration systems, environmental conditions and in their installations). Laboratories located all around the country participated and most of the laboratories with this range of measurement participated. The proficiency test started in November 2006 and finished in March 2007.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

Juan Benjamin Soriano Cardona, Manuel Segura Galindo
Considerations in mass calibration of pressure balance weights
A review of mass calibration of pressure balance weights was developed to explain in detail the considerations around the measurements of mass value determination of each weight applied on the pressure balance that use an accurate mathematical model by industrial and accredited laboratories.
The mass value determination of each weight applied on the pressure balance is an important uncertainty contribution in the estimation of the uncertainty measurement of a pressure balance when used for the calibration of another measuring instrument and in the case where the total measurement uncertainty has to be of high level.
There are different considerations have to be applied to take into account: calibration method of mass values, weights densities values, conventional mass, and estimation of the uncertainty measurement of mass value by whose that use a pressure balance that use an accurate mathematical model to improve the pressure measurement the best of possible.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

M. Caravaggio, G. Molinar Min Beciet, P. De Maria, G. Buonanno, G. Giovinco
FEM analysis for an industrial pressure balance from 3 MPa to 120 MPa in liquid medium
The main purpose of this work is the numerical and experimental analysis of an industrial pressure balance operating in liquid media up to 120 MPa. The numerical prediction of the pressure distortion coefficient, the piston fall rates, the piston-cylinder elastic distortions is achieved through the Finite Element Method (FEM). Numerical results are compared to experimental values and a sensitivity analysis is performed in order to explain some differences between FEM and experimental results.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

G. Buonanno , J. Man, G. Molinar Min Beciet
Characterization of the IMGC-DH100L pressure balance using finite element analysis
The National Measurement Institute of Australia (NMIA) and the Istituto Nazionale di Ricerca Metrologia of Italy together with the University of Cassino (INRIM/UNICAS) have participated in a research project to characterise a INRIM 100 MPa free deformation piston and cylinder assembly using two different numerical procedures based on a finite element method (FEM). The pressure distortion coefficient, ? and the piston fall rates, v were calculated from the clearance profile between the piston and cylinder obtained from dimensional measurement data. Comparison of the numerical results obtained by the two groups showed a relative difference of 2 × 10^-4 in λ and 2.5 × 10^-2 in v. The numerical results were also compared to the experimental results with a relative difference of 1.9 % in λ and 16 % at 100 MPa in v. This paper presents the numerical model used for the calculations of the pressure distortion coefficient and the piston fall rates with a sensitivity analysis of the model for the estimation of the uncertainty values of these two parameters.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

W. Sabuga, T. Priruenrom
An approach to the evaluation of dimensional measurements on pressure-measuring piston-cylinder assemblies
To improve the consistency of 3-dimensional data describing the geometry of pressure-measuring piston-cylinder assemblies, a new approach, based on the leastsquares method, is proposed. It allows the results of diameter-, straightness- and roundness measurements to be linked with each other, with only minimum discrepancies between them. When processing the dimensional data, it is possible thanks to this new approach to weight them differently - according to their measurement uncertainties. The new approach was applied to three gas-operated piston-cylinder assemblies with nominal effective areas of 10 cm² and 5 cm² which are used at PTB as primary gas pressure standards for the range up to 2 MPa. The dimensional measurements were carried out by means of different instruments and the results were analysed. The discrepancies in the dimensional data sets obtained within the scope of the new approach are typically smaller than 16 nm, which agrees with the uncertainties claimed for each kind of dimensional measurement. The effective areas of the three piston-cylinder assemblies were calculated using the Dadson theory and then adjusted taking into account the results of both cross-float measurements carried out between them and pressure measurements carried out against a primary mercury manometer. Finally, relative standard uncertainties smaller than 2·10^-6 could be obtained.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

Hiroaki KAJIKAWA, Tokihiko KOBATA, Kazunori IDE, Akira OOIWA
Precise determination of the jacket pressure coefficient of controlled-clearance pressure balances
We are now developing a new controlled-clearance pressure balance to upgrade the hydraulic high-pressure standard up to 1 GPa. Characterization experiments for a 500 MPa controlled-clearance piston-cylinder were performed in detail over wide pressure range, and the effective area was estimated based on the Heydemann-Welch model. The estimation based on the conventional model agrees well with the present pressure standard. However, at high pressures around 500MPa, there appears some contradictions to the assumption of the model; especially, the jacket pressure coefficient depends apparently on the jacket pressure. A possible revision on the model is briefly discussed.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

Pedro Silva Girão, Octavian Postolache, José Miguel Dias Pereira
Tactile sensors and their use in industrial, robotic and medical applications
This article is about a special type of pressure sensors usually labelled tactile sensors. After a short overview on the subject, two application examples, one in the medical domain developed by the authors for heart rate variability using an electretsbased pressure sensor, are presented.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

A. Nunes, M. Piedade1, R. Neves
Cost Effective Immersive Room with Pressure Sensing Floor
This paper proposes the architecture of a pressure sensing floor divided in rigid tiles. The system is based on a network of flexible pad pressure sensors, used under all tile corners, connected to special local data acquisition circuits. Signals captured by the sensor units are transmitted to a system controller that process, display and store the information received. The proposed architecture was applied in an interactive room with a 64 tiles floor, providing a network weight measuring system that allows detecting, recording and tracking the movement of objects or people over the sensitive area.
The scalable modular network architecture allows the development of cost effective pressure sensing applications in several environments and sensing areas.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

Sari Semenoja, Martti Heinonen
A calibration system for PTU devices
Devices measuring pressure, temperature and humidity simultaneously are known as PTU devices. There are hardly any commercial calibration systems for the PTU devices available for low temperatures (< 0 °C). To obtain more comprehensive data on the performance of PTU devices, a new calibration system is developed at MIKES. In this PTU Apparatus, pressure, temperature and humidity can be controlled simultaneously so that all combinations over the ranges are possible. The nominal ranges of the system are the following: absolute pressure 500 hPa … 1200 hPa, temperature -52 °C … +80 °C and relative humidity 10 % … 95 %. The estimated uncertainties (k = 2) of the pressure, temperature and humidity are 10 Pa, 0,1 °C to 0,3 °C and 1 %RH to 3 %RH, respectively. The construction and operation as well as the results of operational tests of the PTU Apparatus are reported in this paper.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

F. J. Cedillo, R. L. Villeda
Continuous improvement of a Mexican pressure calibration secondary laboratory
The present article has as main objective showing the evolution of a Mexican pressure calibration secondary laboratory based on comparisons. This could be thought to be a reflection of the maturity and metrological culture dissemination from the Centro Nacional de Metrología (Mexican National Centre of Metrology, CENAM). The participation in a total of 10 comparisons through one decade as a secondary laboratory is analyzed in 4 subintervals. Due to the big measurement range covered, from -70 kPa up to 70 000 kPa, to analyzed in only one graph would be a little illustrative.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

M. Rantanen, S. Semenoja and K. Riski
High pressure comparison among seven European national laboratories
An inter-comparison in the high oil pressure range was arranged in 2005 – 2007. The participating laboratories were CMI / Czech Republic, Metas / Switzerland, MIKES / Finland, NMi-VSL / The Netherlands, PTB / Germany, SMD / Belgium and SP / Sweden. The transfer standard was a Desgranges & Huot piston-cylinder unit with a nominal effective area of 1,96 mm², mounted in a D&H 5316 balance body. The participants determined the effective area at ten nominal pressures from 50 MPa to 500 MPa in steps of 50 MPa. All the results were in a good agreement with the reference values, calculated as weighted means of the results from the four primary level laboratories. The results fully support the uncertainties claimed in the CMC tables of the participants.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

M. Kojima, K. Saitou and T. Kobata
Study on calibration procedure for differential pressure transducers
The indications of some types of differential pressure transducers are affected by the calibration procedure such as pressurization sequence, the line pressure and environmental conditions: it is known that hysteresis, zero drifts and span readings of some transducers depend on those parameters. When the calibrated transducer is used as a working standard in another calibration, therefore, it is necessary to use the same procedure as previous calibration. Otherwise, the calibration results sometimes differ according to the measurement condition. As an example, the different calibration results obtained by two working standards which have different dependency on pressurization sequence are shown in the report. Also the line pressure dependency of a transducer was evaluated by changing the line pressure from 25 kPa to 175 kPa in the range of differential pressure from 1 Pa to 1000 Pa.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

T. Kobata,M. Kojima, and H. Kajikawa
Towards establishment of remote calibration for pressure standards
A remote calibration technology for disseminating pressure standards has been developed. Currently, the technology is developed in two different pressure ranges. One is gas differential pressure from 10 Pa to 10 kPa with the line pressure of atmospheric pressure and the other is hydraulic pressure from 10 MPa to 100 MPa in gauge mode. In both pressure ranges, the measurement protocol for the remote calibration using a transfer standard has been examined. Also the transfer standard for the remote calibration has been developed in either pressure range. Using the protocol and the developed transfer standard, the demonstration experiments for the remote calibration were performed. In this paper, the measurement protocol and the transfer standard developed for the remote calibration are described and the results obtained from the experiments are shown.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

D. Zvizdic, L. Grgec Bermanec, W. Schultz, T. Veliki
Characterization of LPM diving-bell manometer
This paper presents characterization of diving-bell manometer in the gauge pressure range from -1.0 up to 3.0 kPa in the Croatian national pressure laboratory - Laboratory for Process measurement (LPM), located at the Faculty of Mechanical Engineering and Naval Architecture (FSB), University of Zagreb.
The work points out comparison of two independent methods for diving-bell effective area determination i.e. determination based on dimensional measurements as well as determination of the effective area by a pressure comparison method. The dimensional measurements were performed in the Croatian national length laboratory, also at FSB.
Determination of the effective area by the pressure comparison method was performed in LPM using a Physikalisch-Technische Bundesanstalt (PTB) Rosemount pressure transducer previously calibrated in PTB Braunschweig. From the results it can be seen that the difference in the effective areas obtained with the two independent methods is very small compared to the estimated effective area measurement uncertainties.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

T. Kobata
A fully automated calibration system for pressure balance
A new fully automated system for calibrating a pressure balance is described. The system consists of two automated pressure balances, a pressure controller, two air-operated constant volume valves, a precise pressure transducer, a device for measuring environmental condition, a computer and the program developed. In the system, one pressure balance is used as a standard and the other is calibrated and/or evaluated. To determine the equilibrium state between two pressure balances accurately, the cross-float measurement using the comparator method is performed. In this paper, the details of the system are described and the results obtained using the system are shown.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

S. Woo, I. Choi, H. Song, B. Kim
New differential pressure standard at KRISS
The accurate measurement of differential pressure at low-line pressure is important in many industrial and commercial activities. The Korea Research Institute of Standards and Science(KRISS) has completed the development of a low differential pressure primary standard covering a range from 1 Pa to 15 kPa for operation with line pressures of 100 kPa. The standard is based on a double pressure balance and includes a test-instrument manifold with pressure controllers. It has a peculiar automatic weight handling mechanism which enables the various weights easily to add or remove from the piston without breaking the reference vacuum during calibration. The performance of the standard has been evaluated using commercial precise differential pressure gauges.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

M. Bair, P. Delajoud and M. Girard, DH INSTRUMENTS
The design and implementation of a fully automated crossfloat system for the comparison of piston gauges in both gauge and absolute measurement modes
The pressure crossfloat is a well established method for comparing the output of piston gauges with various media. The crossfloat is the most common method for determining the area of a test piston-cylinder relative to a reference piston-cylinder. The traditional crossfloat procedure is a tedious manual process that is highly dependent on operator skill, patience and experience. Due to the need to access the masses to make small mass adjustments, operation is normally gauge mode only.
In order to meet a high demand for low pressure, gas operated piston gauge systems, DHI has designed and implemented a fully automated crossfloat system over the range of 9 kPa to 7 MPa. The intent of the system is to be able to perform unattended crossfloats to determine the test piston-cylinder performance characteristics and determine effective area in either absolute or gauge mode. The crossfloat station was put into regular operation in late 2006 and has exceeded the expectations of its designers.
The automation is made possible by the use of two automated mass handling systems and a low differential pressure transmitter used to determine the final equilibrium point between the two piston-cylinders.
This paper describes the design of the automated calibration system, the challenges of its implementation and the results of numerous crossfloats performed over six months of automated operation.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

Pierre Otal, Jean-Claude Legras
Three technologies met in the absolute pressure range 0,5 Pa to 3 Pa
The LNE standards around 1 Pa absolute are constituted by a force-balanced piston gauge (FPG), 100 Pa capacitance diaphragm gauges (CDGs), and spinning rotor gauges (SRGs). The key parameters limiting the performance of the devices are presented. The results of a comparison involving at the same time the three instruments are presented and discussed, as well as the capabilities of these instruments in this range. As an example, the repeatability of measurements, and the linearity error in the comparison are less than 2 mPa.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

Nieves Medina, Salustiano Ruiz, Carmen Matilla
Developments in the Pressure field at CEM
In the near future new pressure standards will be operative at CEM. These standards together with the existing will provide traceability to the whole pressure range. These standards are a mercury column, a force piston gauge and a static expansion system.
The mercury column is a U-shaped steel tube filled with mercury. Its measurement principle is Torricelli´s law. The height difference between the two columns is measured by means of a single-beam helium–neon laser interferometric system. Its measurement range is from 1 kPa up to 130 kPa in absolute, relative and differential modes.
The force piston gauge is a recent acquisition. It is a pressure standard designed to cover the range from less than 1 Pa to 15 kPa gauge and absolute pressures. The instrument operates on the piston gauge principle in which the pressure on the piston is measured by a forced balanced load cell.
The static expansion system is based on Boyle´s law with some corrections. This standard will work from 10^-4 Pa to 103 Pa. This system consists of two large 100-litre volumes, two 1-litre volumes and a 0.5-litre volume. The system is evacuated by means of two 300 l/s-turbomolecular pumps connected to the large vessels. Both of them will be connected to a primary dry pump.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

In-Mook Choi, Sam-Yong Woo, and Boo-Shik Kim
A Study Of Carbon Nanotube-Based Ionization Gauges
Low-pressure detection technology utilizing the field emission of carbon nanotubes (CNTs) is introduced. The use of an ionization gauge is a viable alternative method for measurements at low pressure levels, but their use is limited by such factors as the bulky size, high power consumption, x-ray radiation, heat and light generation, and outgassing associated with this type of gauge. To overcome the limitations of conventional ionization gauges, CNTs have been proposed as an electron source. The performance of a CNTbased low-pressure gauge, including the sensitivity, measurement range, and linearity, has been improved greatly by changing the structure of the electrodes. The sensor showed a linear pressure measurement range from 5·10^-7 to 10^-2 Torr. Furthermore, the service life of the CNT emitter could be extended greatly by modulating the pulse of the voltage with a 20 % duty ratio. However, the service life of the CNT-based sensor is especially short, particularly when it is used at relatively high pressure levels. Accordingly, a CNT array directly grown by thermal Chemical Vapor Deposition is proposed. An integrated emitter directly grown with a catalyst metal can provide a low turn-on field by reducing the distance between the grid and CNTs while providing a longer emission lifetime. The characteristics of the directly grown CNT array and the screen-printed CNT array are compared for possible use with a practical pressure sensor.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

Christian Wüthrich
The New Static Expansion System Of METAS
The METAS static expansion system was built in 2004 and has been extensively characterised during the last two years.
The system consists of four expansion stages allowing the generation of calculable pressures ranging from 5·10^-6 Pa up to 2000 Pa.
Uncertainty calculation yields a relative uncertainty of 0.001 (k=2) for the volumetric ratio of the expansion stage. The relative uncertainty on the pressure obtained after expansion is 0.003 above 10 Pa, it is still 0.01 at 2·10^-4 Pa.
Measurement of the accommodation coefficient of two SRG from 10^-5 Pa up to 0.1 Pa has shown no significant deviation of the accommodation coefficient over the full range of measurement and over a period of time of 18 months.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

Anita Calcatelli
The Development Of Vacuum Measurements Down To Extremely High Vacuum –XHV
The available measuring devices in the ultra high and extreme high vacuum range with their limitations are presented on the basis of the ultimate attainable pressure. New miniature gauges and calibration devices up now available are shortly reviewed. A complete bibliography is presented.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

Karl Jousten
Traceability to SI units for Vacuum Measurement in Industrial applications
In the context of international standards like the ISO 9000 series or ISO 17025 the traceability of measurement instruments of physical units in industrial processes gained more importance in the last two decades, so to say also for vacuum measurement. Traceable calibrations of vacuum gauges ensure agreement with the SI units. For this purpose vacuum primary standards are needed. The international system of metrology ensures that the vacuum primary standards registered in the system are equivalent and fulfil their specifications. Secondary and reference standards are used to disseminate the pressure scale in vacuum to calibration laboratories, to the manufacturers of gauges, and finally to industrial processes or to research facilities. Suitable vacuum gauges for this purpose including their expected measurement uncertainties will be described. Notes for the measurement uncertainties at the place of the end user will be given.
3rd Conference on Pressure Measurement (together with 20th Conference on Measurement of Force, Mass and Torque & 1st Conference on Vibration Measurement), Merida, MEXICO, 2007

P R O C E E D I N G S

Year of event

TC

Event

Authors/Title

Keyword(s)

Abstract